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editorsWorld Agriculture Editorial BoardPatronsProfessor Yang Bangjie, Member of the Standing Committee of the National People’s Congress of China.(China)Lord Cameron of Dillington, Chair of the UK All Party Parliamentary Group for Agriculture and Food forDevelopment. (UK)Maxwell D. Epstein, Dean Emeritus, International Students and Scholars, University of California, LosAngeles.(USA)Sir Crispin Tickell, GCMG, KCVO, formerly, British Ambassador to the United Nations and the UK’s PermanentRepresentative on the UN Security Council (UK)

Managing Editor and Deputy ChairmanDr David Frape BSc, PhD, PG Dip Agric, CBiol, FRSB, FRCPath, RNutr. Mammalian physiologist

Regional Editors in ChiefRobert Cook BSc, CBiol, FRSB. (UK)Plant pathologist and agronomistProfessor Zhu Ming BS, PhD (China)President of CSAE & President of CAAE Scientist & MOA Consultant for Processing of Agricultural Products &Agricultural Engineering, Chinese Academy of Agricultural Engineering

Deputy EditorsDr Ben Aldiss, BSc, PhD, CBiol, MSB, FRES. (UK)Ecologist, entomologist and educationalistDr Sara Boettiger B.A. ,M.A.,Ph.D (USA)Agricultural economistProfessor Neil C. Turner, FTSE, FAIAST, FNAAS (India), BSc, PhD, DSc, (Australia)Crop physiologist,Professor Wei Xiuju BS, MS, PhD (China)Executive Associate Editor in Chief of TCSAE, Soil, irrigation & land rehabilitation engineer

Members of the Editorial BoardProfessor Gehan Amaratunga BSc, PhD, FREng, FRSA, FIET, CEng. (UK & Sri Lanka) Electronic engineer & nanotechnologist Professor Pramod Kumar Aggarwal, B.Sc, M.Sc, Ph.D. (India), Ph.D. (Netherlands), FNAAS (India), FNASc(India)Crop ecologistDr Andrew G. D. Bean, BSc, PhD, PG Dip. Immunol. (Australia)Veterinary pathologist and immunologistProfessor Tim Benton, BA, PhD, FRSB, FLSFood systems, food security, agriculture-environment interactionsProfessor Phil Brookes BSc, PhD, DSc. (UK)Soil microbial ecologistProfessor Andrew Challinor, BSc, PhD. (UK)Agricultural meteorologistDr Pete Falloon BSc, MSc, PhD (UK)Climate impacts scientistProfessor Peter Gregory BSc, PhD, CBiol, FSRB, FRASE. (UK)Soil scientist Professor J. Perry Gustafson, BSc, MS, PhD (USA)Plant geneticistHerb Hammond, (Canada) Ecologist, forester and educatorProfessor Sir Brian Heap CBE, BSc, MA, PhD, ScD, FRSB, FRSC, FRAgS, FRS (UK) Animal physiologistProfessor Fengmin Li, BSc, MSc, PhD, (China)AgroecologistProfessor Glen M. MacDonald, BA, MSc, PhD (USA)GeographerProfessor Sir John Marsh, CBE, MA, PG Dip Ag Econ, CBiol, FRSB, FRASE, FRAgS (UK)Agricultural economistProfessor Ian McConnell, BVMS, MRVS, MA, PhD, FRCPath, FRSE. (UK)Animal immunologist Hamad Abdulla Mohammed Al Mehyas B.Sc., M.Sc. (UAE)Forensic GeneticistProfessor Denis J Murphy, BA, DPhil. (UK)Crop biotechnologist Dr Christie Peacock, CBE, BSc, PhD, FRSA, FRAgS, Hon. DSc, FRSB (UK & Kenya)Tropical AgriculturalistProfessor R.H. Richards, C.B.E., M.A., Vet. M.B., Ph.D., C.Biol., F.S.B., F.R.S.M., M.R.C.V.S., F.R.Ag.S. (UK)AquaculturalistProfessor John Snape BSc PhD (UK)Crop geneticistProfessor Om Parkash Toky, MSc, PhD, FNAAS, (India)Forest Ecologist, Agroforester and SilviculturistProfessor Mei Xurong, BS, PhD Director of Scientific Department, CAAS (China)Meteorological scientistProfessor Changrong Yan BS, PhD (China) Ecological scientist

Advisor to the boardDr John Bingham CBE, FRS, FRASE, ScD (UK)Crop geneticist

Editorial AssitantsDr. Zhao Aiqin BS, PhD (China) Soil scientistMs Sofie Aldiss BSc (UK)Rob Coleman BSc MSc (UK)Michael J.C. Crouch BSc, MSc (Res) (UK)Kath Halsall BSc (UK)Dr Wang Liu. BS, PhD (China) HoriculturalistDr Philip Taylor BSc, MSc, PhD (UK)

Published by Script Media, 47 Church Street, Barnsley,

South Yorkshire S70 2AS, UK

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Volume 5, Number 2 contentsIn this issue ...

Published by Script Media, 47 Church Street, Barnsley,

South Yorkshire S70 2AS, UK

editorials:� Weak international institutions prevent the full benefits of science based innovation being secured for consumers or the environment 4-5 Professor Sir John Marsh

� Good Fats, Obesity, CVD and GM 6Dr David Frape

scientific:� Oils and fatty acids essential for vertebrate health – e.g. fish and Man 7-14Dr David Frape

� The supply of fish oil to aquaculture: 15-23a role for transgenic oilseed cropDr Richard P Haslam, Dr Sarah Usher, Dr Olga Sayanova, Professor Johnathan ANapier, Dr Monica B Betancor, Professor Douglas R Tocher

� What is the future for oil palm as a global crop 24-34Professor. Denis J. Murphy

� Revised instructions to contributors 35-36

� Errata from previous issue 6

Future papers for Spring Issue 2016:� Aquaculture: are the criticisms justified? III – Fish Farming and Atlanticsalmon.Professor Dave Little and Dr Jonathan Shepherd

� Crop landraces: A rediscovered, multifuctional and irreplaceable componentof agrobiodiversity.Dr Pinelopi BeBeli et al.

� Disease resistance and food production Dr Andrew Bean

� ‘Climate-smart villages – a model to promote synergies between produc-tion, adaptation and mitigation in agriculture’ Prof. Pramod Aggarwal et al.

� Innovative agroforestry for livelihood and environment security in IndiaDr A.K. Handa, Professor O.P. Toky and Dr S.K. Dhyani

If you wish to submit an article forconsideration by the EditorialBoard for inclusion in a section ofWorld Agriculture: a) Scientificb) Economic & Socialc) Opinion & Comment ord) a Letter to the Editorplease follow the Instructions toContributors printed in this issueand submit by email to the Editoreditor@world-agriculture.netghgh

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Weak international institutionsprevent the full benefits of science

based innovation being secured forconsumers or the environment

Solutions andconfrontations

Two of the papers in this editionshed light on assertions commonlymade by pressure groups.

Murphy, contrary to their claims,shows that expanding plantation palmoil production gives a smallerenvironmental footprint than traditionalsmall-scale production.

Haslam et al., explain the inability ofcapture fisheries to sustain the level ofdemand for long chain Omega 3 fattyacids, necessary to meet the nutritionalneeds of farmed fish of which there is agreatly increased rate of production,demanded by a growing humanpopulation.

They show that the feed requirementsof farmed fish may be satisfied bymodified vegetable oils, rather than bydepleting stocks of sea fish. In bothpapers the key technology needed tomeet growing demand whilstminimising environmental costsdepends upon genetic manipulation.

Both papers offer grounds foroptimism that, at a time whenpredicted growth of demand fromrising numbers of people and risingincome, technology can offer theprospect of reducing further pressureson the natural environment.

If production is limited to currenttechnology there are likely to belimitations on sustainable supplies thatwill require either, some reduction inthe numbers of people, or a reductionin per-capita consumption, effectively areduction in real income. Neitherstrategy is politically acceptable.Inaction will mean that the burden ofadjustment will fall on people who areeconomically weakest, owing to aninevitable increase in prices as suppliesdiminish.

In contrast these papers show, for twoimportant areas, palm oil and fish oilsupplies of ‘omega 3’, productivity canbe substantially increased withoutirreparable damage to the environment.

Innovation at this fundamental levelmeans moving into territory that is new.That means facing up to the possibilityof unrecognised and damaging sideeffects for either human health or theenvironment. If we are to exploit suchpossibilities we need to abandon thenegative philosophy of theprecautionary principle and establish awell equipped, broadly based andtrusted system of monitoring.

This must be the responsibility ofgovernment, ideally but probablyimpracticably, on a global basis. Such aservice must command the confidenceof the public. In doing so it needs notonly to publish its own monitoringreports but also address, and wherenecessary contest, positions adopted bypressure groups – one of the functionsof World Agriculture.

Research and development are notluxuries but necessities, if we are tocope with the challenges that lie ahead.Innovations that increase productivityoften emerge from interactions betweenscientists in their own specialistlanguages.

To discover and apply suchproductivity-enhancing possibilitiesneeds research to be communicated inlanguage that is understood by policymakers and decision takers.

Communication should be a two wayprocess. Scientists need to be aware ofwhat communities want so that theyrecognise the potential of their newdiscoveries. World Agriculture providesone route through which thiscommunication can take place.

The importance of a globalviewA second feature common to thesepapers is the need to visualise bothproblems and solutions on a globalbasis.

National boundaries are artificial andpolitical decisions in one location oftenhave unrecognised repercussions onnatural processes in distant places.

Production of palm oil, greatly indemand in high and middle-incomecountries, has expanded dramatically inIndonesia and Malaya bringing changesin wildlife habitat, the decline oftraditional communities and exposingthe economic stability of both countriesto fluctuations in the world price of oil.

Similarly, increased success in locatingand capturing fish has threatened thesustainability of fish populations anddestroyed the livelihoods of traditionalfishing communities that have noalternative source of income.

Palm oil production is concentrated inS E Asia but its impact on the naturalenvironment may affect the welfare ofcommunities in other continents.

Deforestation in order to increase foodsupplies can have adverse consequencesfor climate change.

The loss of biodiversity, as traditionalhabitats are destroyed, may not onlydestroy treasured wild life but deprivethe world of genetic resources.

The need to control pests andovercome diseases that threateneconomically productive farming notonly reduces bio-diversity but also mayreduce the aesthetic value oflandscapes. Success in producing morefood is likely to result in increasedpressure on natural water supplies.

The tensions that result may lead toconflicts between countries dependenton the same natural sources of water. Inall these areas we need a regulatoryframework that takes a world wide view.

Attempts to reach a globalconsensus on action to regulate theexploitation of natural resources havedemonstrated the impotence ofinternational institutions.

Governments, faced byenvironmental problems that aregeographically or temporally remoteare likely to give greater weight tocompeting demands from local, well-organised pressure groups. Retainingpower depends on those whose voteswill determine their own continuationin office.

Professor Sir John Marsh

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editorialsPrestige abroad will not win votes athome. As a result internationalagreements, and their enforcement,tend to proceed at the rate of themost reluctant.

These papers offer prospects formore efficient resource use byemploying genetically modifiedmaterials. If this is frustrated byrestrictions on trade in GM productsthe result will be avoidable

environmental and economic cost forthe world as a whole.

Most of the world’s population seek ahigher standard of living. But suchgoals are unattainable if productivitylevels do not increase.

The rejection of productivity-increasinginnovation not only penalises those whoare now poor but eventually will imposea decline in living standards on manywho are currently affluent.

Such a prospect stresses theimportance for global welfare that welearn to use available natural resourcesmore efficiently.

The papers by Murphy and Haslam etal. provide an example of how sciencecan contribute to resolve problems inspecific product areas to improveefficiency and safeguard naturalresources for the world community as awhole.

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Vegetable oils provide more thantwice as much net energy perunit weight, compared with

proteins or carbohydrates. Fatty foods therefore contribute to

obesity in the Western world. Obesityis a contributory factor to the wideoccurrence of cardio-vascular disease(CVD) and type 2-diabetes (T2D).Hence, studies to compare the specificeffects of fats on CVD replacingcarbohydrates must be conducted onthe basis of equalizing total energyintake. But surveys of large populationsof people to assess the effects ofdietary factors, especially fats, on theincidence of CVD, T2D and of cancers,in particular, have the problem ofdistinguishing the effects of thosefactors separately from that of bodyweight, or body mass index.

With large amounts of data it ispossible to control some of theconfounding factors statistically.

The evidence from these studiesgenerally points to a relationshipbetween the consumption of saturatedfats (fatty acids) and CVD,independent of body weight, or bodymass index.

Nevertheless, I conclude a majorhealth benefit of the MediterraneanDiet over that of Northern Europe, isnot that there is any difference in fatcontent, but that much of the fat inthe former diet is in the form ofuncooked oil, whereas that oil inNorthern Europe is largely replaced bymargarine, for which there is nocontrol by the EU of its trans-fatcontent (see Frape this Issue pp 7-14).

In this Issue we publish twoimportant papers on fats. One, is byHaslam and colleagues, on apolyunsaturated substitute for fish oilin GM-modified false flax (Camelinasativa), that contains highconcentrations of two dietary essentialhighly unsaturated fatty acids.

The second is on palm oil, an oil richin palmitic acid, a saturated fatty acid.Palm oil is derived from the African oil

palm, Elaeis guineensis, the majorglobal vegetable oil crop.

Palm oil is consumed daily by overtwo billion people. Murphy, in thisissue, informs us that the production ofthis oil to meet an ever increasingdemand has led to extensiveconversion of tropical forests toplantations.

In some parts of Southeast Asia, thishas had major adverse ecological andenvironmental consequences, with areduction in biodiversity, damage tosoil and the release of greenhousegases during the initial clearance of theplanting area.

These consequences have led to callsfor boycotts of products containingpalm oil. (A haze is apparent over areasof Malaysia each year caused byburning of natural forest andprohibiting air flights.)

But this crop provides an example ofthe importance of advanced breedingmethods, particularly genomics, whichare beginning to bear fruit in terms ofcrop improvement for yield andquality. Without these developmentseven greater areas of natural forest willbe destroyed to keep pace with thedemand.

Palm oil has the benefit of beingrelatively stable during storage, owingto its high content of palmitic acid, afully saturated fatty acid; yet this fattyacid has the disadvantage of itsrelationship to risk factors of CVD.

Olive oil, on the other hand, forwhich there is a very much lower yieldof oil/ha, is rich in oleic acid, amonounsaturated fatty acid, which isconsidered to be healthy. Palm oilcontains only half this amount of oleicacid.(see, Frape, this Issue).

The paper by Haslam and colleaguesrelates to the worldwide shortage oflong chain,polyunsaturated omega-3fatty acids, with five and six doublebonds (EPA and DHA) that areconsidered important in human health.

Presently the only significant sourceof these polyunsaturated omega-3 fattyacids is monocellular oceanic plant

organisms, that are consumed by wildfish, thereby making fish an importantsource of omega-3 fatty acids forhumans. These fatty acids are alsocritical in the diet of farmed fish.

Wild fish stocks are under extremepressure, owing to over-fishing to meetthe increasing demands of a growingworld population. Moreover, wild fishare under increasing stress owing tothe warming of oceans, which reducesoxygen tension. In order to overcomethe scarcity of fish oils rich in these twofatty acids, Haslam et al. at Rothamsteddescribe the transfer of a group ofgenes from these oceanic organisms toCamelina sativa, false flax. These genesare needed for the production of EPAand DHA.

This plant was chosen as it is a richsource of a-linolenic acid, a C18:3omega-3 fatty acid, the startingmaterial for the required chain ofreactions, and Camelina can becropped in temperate climates andcould become an essential source ofEPA and DHA for fish farming as thecurrent source from wild fish oils,becomes increasingly scarce.

As noted above, these fatty acids areessential nutrients in the diet of Manand so Camelina would provide anadditional and crop-based source.

Both these papers define a role formodern genetic manipulation of crops.

Without the adoption of GM andother related methods of plantbreeding it will be impossible to feedthe growing numbers of people,amongst whom, the first to suffer willbe those groups that are economicallydisadvantaged.

Moreover, biodiversity will suffer at afaster rate if man does not adoptmethods developed and proven byresearch, and the products of thatresearch are then shown to be safe forhuman consumption.

The reason for this is that even largerareas of our natural landscape willneed to be converted to farmland ifreliable new research is not adopted inpractice.

Good Fats, Obesity, CVD and GMDavid Frape

Errata

Vol. 5, No. 1, Falloon et al.1. Page 36 second column, third paragraph “Figure 9 (from 109)” should be 110, not 1092. Similarly on p 36 in the figure 9 legend – should be (from 110), not (from 109)3. Page 28, third column, end of 4th paragraph “wild crop ancestors (27)” should be 37, not 27.

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Definitions – what are fats?LipidsLipids are a group of naturallyoccurring compounds that include fats,waxes, sterols, including cholesterol,fat-soluble vitamins (such as vitaminsA, D, E, and K), monoglycerides,diglycerides, triglycerides,phospholipids, and others.

The main biological functions of lipidsinclude storing energy, signalling andacting as structural components of cellmembranes.

Lipids have applications in thecosmetic and food industries as well asin nanotechnology. Although the termlipid is sometimes used as a synonymfor fats, fats are a subgroup of lipidscalled triglycerides or triacylglycerols.

Triglycerides(Triacylglycrols )

Triglycerides are the main constituents ofvegetable oil (typically containing moreunsaturated fatty acids) and animal fats(typically with more saturated fatty acids),see Figure 1 for a typical structure.

Figure 2 shows four different fatty acids.Stearic acid is completely saturated, i.e. ithas single bonds (-CH2-CH2-) betweenthe carbon atoms in its chain.

Saturated fatty acids are “saturated”with hydrogen – all available places wherehydrogen atoms could be bonded tocarbon atoms are occupied i.e. eachcarbon has two H atoms attached to it,whereas the omega (end of the C chain)will have three i.e. a methyl group.

Unsaturated compounds have doublebonds (-CH=CH-) between carbon atoms,reducing the number of places wherehydrogen atoms can bond to carbonatoms to one H atom per C atom, as inoleic acid and in a-linolenic acid (Fig. 2).

These carbon bonds are under stress andthus open to oxidation, or to rotation.

The fatty acid bonds to the glycerolthrough its acyl (carboxyl) group informing a fat. Unsaturated fats have alower melting point and are more likely to

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Oils and fatty acids essential for vertebrate health – e.g.

fish and ManDr David Frape

SummaryThis paper provides explanations both of why essential fatty acids are essential and of biochemical terms which are widelyused by the general press. These explanations should aid an appreciation of two of our papers in this issue especiallythat by Haslam et al. Vegetable oils are extracted mostly from seeds of maize, soyabean, sunflower, linseed, rape,olive, and palm. These oils provide over twice as much net energy/kg compared with starch and so their consumption cancontribute to obesity with its adverse effects on health. They are a source of two essential dietary nutrients in the form ofthe polyunsaturated fatty acids (PUFA), C18:2 6 linoleic acid and C18:3, 3, a-linolenic acid. Olive oil is also a rich source ofC18:1, 9, oleic acid, a monounsaturated fatty acid (MUFA), which may contribute to its health benefits. Long chain omega-3 fatty acids, C20:5, 3, eicosapentaenoic acid (EPA), and C22:6, 3, docosahexaenoic acid (DHA) are also essential in thediet of vertebrates, but the only major primary source of them is oceanic mono-cellular organisms, phytoplanktons andalgae, the foodstuff of oceanic animal life. Thus, production of these oils from a crop which can be grown in temperateclimates will be an essential source for fish farming, where their current source from wild fish oils, is becoming scarce. EPAand DHA consumption beneficially influence risk factors of cardio-vascular disease (CVD) when they replace saturated fats inthe diet. They are more potent than are a-linolenic acid and linoleic acid, or than oleic acid. All these unsaturated fatty acidsare protective against CVD, in comparison to saturated fatty acids, e.g. palmitic acid (C16:0). Nevertheless, palm oil is richin both palmitic acid and oleic acid (Table 1). Olive oil contains a larger proportion of oleic acid and less palmitic acid thandoes palm oil, and is considered to be protective. Nevertheless, unsaturated fats are prone to oxidation and rancidity,whereas saturated fats are relatively stable and the hydrogenation of unsaturated vegetable oils during the production ofmargarine leads to cis—trans isomerisation of unsaturated fats. The trans-isomers have been shown to raise plasma LDLcholesterol levels and to pose a risk for CVD. Hence, legislation has been introduced in the USA, where trans-fat levels mustbe declared on the labels of appropriate products in the USA. However, compared with the relationship of fatty acids withthe risk factors of CVD, the correlation of all these risk factors with the occurrence of CVD is less well secure, for the obviousreason that individuals do not eat nutrients, but mixed diets; so there is confounding of factors on the response to thedietary environment of individuals. Some clarification of this situation is possible in population studies.

Key words fats, lipids, risk factors, CVD, GM, definitions

AbbreviationsCVD, cardiovascular disease; GRAS, generally recognized as safe; MUFA, monounsaturated fatty acids; PUFA, polyunsaturated fattyacids.

Fig. 1 A triglyceride is a compoundderived from glycerol and three fattyacid alkyl chains, R1, R11 and R111,forming an ester through their acylgroup. These three chains may beidentical, or each one may have adifferent formula.

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be liquid at room temperature. Saturated fats have a higher melting

point and are more likely to be solid atroom temperature. Melting point is alsodetermined by C chain length of the fattyacids shorter chains have a lower meltingpoint. Most natural fats contain a complexmixture of individual triglycerides. Becauseof this, they melt over a broad range oftemperatures.

Polyunsaturated fatty acids act asvaluable structural components in cellmembranes, whereas saturated fats, notused as energy sources, tend toaccumulate in the liver, viscera andsubcutenaeous fat depots and are acomponent of arterial plaques.

Fatty acidsThese are chain-like molecules, thecarboxylic acid (-COOH) end of whichis considered the beginning of thechain, thus “alpha” with the methyl(CH3) end, as the “tail” of the chain,thus “omega.” Nevertheless, the wayin which a fatty acid is named isdetermined by the location of the firstdouble bond, frequently counted fromthe methyl end, that is, the omega( -) or the n- end.

The chain lengths of the fatty acids innaturally occurring triglycerides vary,but most contain 16, 18, or 20 carbonatoms. Natural fatty acids found inplants and animals are typicallycomposed of only even numbers ofcarbon atoms.

Bacteria, however, possess the abilityto synthesise odd- and branched-chainfatty acids.

As a result, ruminant animal fatcontains some odd-numbered fattyacids, such as 15, owing to the action

of bacteria in the rumen. (see Table 1)A short notation is used to define those

of each type of fatty acid n.b. see underTransisomers, below, for an explanationof the term “cis”:C18:0 denotes an acid with 18 Catoms in its chain, all of which aresaturated with H atoms, a SFA.C18:1, 9 (also known as C18:1n-9),oleic acid, a MUFA, denotes a fattyacid with 18 C atoms in its chain, butit has one unsaturated cis-bond, whichis 9 C atoms from the omega ( or n)end, i.e. the methyl-group, of thechain.C18:2, 6 (also C18:2n-6), linoleicacid, a PUFA, denotes a fatty acid with18 C atoms in its chain, but it has twounsaturated cis-bonds, the first ofwhich is 6 C atoms from the end ofthe chain, whereas the second doublebond is 9 C atoms from the end ofthe chain. This is a polyunsaturatedfatty acid (PUFA). It is one of theessential fatty acids, so calledbecause they are necessary forhealth, and they cannot beproduced adequately within thehuman body. They must be acquiredthrough diet.). All PUFAs are dietaryessential in humans.C20:5, 3 (also C20:5n-3), EPA, aPUFA with 20 C atoms in its chain withfive unsaturated cis-bonds, the first ofwhich is 3 C atoms from the end ofthe chain, whereas the otherdouble bonds are 6, 9, 12 &15 Catoms from the end of the chain.C22:6, 3 (also C22:6N-3), DHA, aPUFA with 22 C atoms in its chain, butwith six unsaturated cis-bonds, the firstof which is 3 C atoms from the endof the chain, whereas the other doublebonds are 6, 9, 12 ,15 & 18 C atoms

from the end of the chain. This isanother PUFA.C18:3, 3, a-linolenic acid (ALA), ann-3 PUFA with an 18-carbon chain andthree cis double bonds. The firstdouble bond is located at the thirdcarbon from the methyl end of thefatty acid chain, known as the n end-the other two are located at carbons 6and 9.

Thus, a-linolenic acid is apolyunsaturated n-3 (omega-3) fattyacid. ALA is found in seeds: chia,flaxseed, nuts (notably walnuts), and inmany common vegetable oils. In termsof its structure, it is also named fromthe alpha-end as all-cis-9,12,15-octade-catrienoic acid. Its isomer is gammalinoleic acid GLA is 18:3 (n-6).n.b. I used the term cis. It isunfortunately important to understandthis term, as legislation is in theprocess for the declaration of the cis-trans composition of fats in foodproducts (see Trans-Isomers, below).

N-3, Omega, 3Terrestrial plants can be rich in 18CPUFA such as linoleic acid (18:2 6)and a-linolenic acid (ALA, 18:3 3),but the biologically most activeomega-3 fatty acids in fish are thelong-chain polyunsaturated 3 fattyacids primarily EPA (20 carbons and 5double bonds) and DHA (22carbons and 6 double bonds) (Fig. 3).

Some freshwater and salmonidspecies of fish can produce EPA andthen from EPA, the more crucial, DHA,but most marine fish are unable todo so in adequate quantities from theshorter-chain omega-3 fatty acid ALA(18 carbons and 3 double bonds)provided in dietary plant sources.

The ability of vertebrates to makethese longer-chain omega-3 fatty acidsfrom ALA may be impaired even moreby aging, and is generally considerednot to exceed 5%, so this ability isinadequate to meet their dietaryrequirement.

It may be concluded that vertebrates,including fish, cannot adequatelysynthesise PUFAs (i.e. fatty acids withmore than one double unsaturatedbond) because they lack the enzymesrequired for their production frommonounsaturated fatty acids.

Trans-isomers (see Fig. 4)An unwelcome side effect occursduring the partial hydrogenation of theunsaturated fat when some of the cisdouble bonds are converted into transdouble bonds by an isomerizationreaction with the catalyst used for thehydrogenation during production to

Figure 2 The structural formulae of four fatty acids, the lower two of which aredietary essential fatty acids, in that mammals and fish are incapable of theirsynthesis from non-essential fatty acids. n.b. The methyl group is at the omegaend of the chain, regardless of its length (also known as the n end)and the carboxyl group is at the alpha end.

C18:1 9

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raise the melting point of productssuch as margarine.

Cis and trans forms are known asgeometric isomers of fatty acids. Theyare structurally identical except for thearrangement of the double bond, andso the location of the two H atoms inrelation to the two carbons is changed.

Most natural fatty acids have a cis-configuration i.e. vegetable sources.

The fatty acids in Figs 2 and 3 are allindicated as cis-isomers.

Fig. 4 indicates the change in the bondduring trans formation – a structuralarrangement possessing a lowerenergy.

There is pressure on legislators toplace a legal limit on trans-isomers ofunsaturated fatty acids, especially inhydrogenated vegetable fats. In 2013,the United States Food and DrugAdministration (FDA) issued apreliminary determination that partiallyhydrogenated oils (which contain transfats) are not “generally recognized assafe”.

On 16 June 2015, the FDA in the USAset a three-year time limit for theirremoval from all processed food. Transfats levels can be reduced oreliminated using saturated fats!1.

High intake of trans fatty acids canlead to human health problems as itcontributes to obesity, high bloodpressure, and a greater risk for heartdisease.

Trans fat is abundant in fast foodrestaurants. It is consumed in greaterquantities by people who do not haveaccess to a diet consisting of fewerhydrogenated fats, or who oftenconsume fast food2.

Health and trans fatsThere are two accepted blood teststhat measure an individual’s risk forcoronary heart disease.

The first considers ratios of two typesof cholesterol, the other the amount ofa cellsignalling cytokine called C-reactive protein. The ratio test is moreaccepted, while the cytokine test maybe more powerful. The effect of transfat consumption has beendocumented3,4,5 .Cholesterol ratio: This ratio comparesthe levels of LDL to HDL. Trans fatbehaves like saturated fat by raising thelevel of LDL, but, unlike saturated fat, it

has the additional adverse effect ofdecreasing levels of HDL.

The net increase in LDL/HDL ratiowith trans fat is approximately doublethat due to saturated fat. (Higher ratiosare worse.).C-reactive protein (CRP): A study ofover 700 nurses showed that those inthe highest quartile of trans fatconsumption had blood levels of CRPthat were 73% higher than those inthe lowest quartile6,7,8.

A 2006 study supported by theNational Institutes of Health and theUSDA Agricultural Research Serviceconcluded that palm oil is not a safesubstitute for partially hydrogenatedfats (trans fats) in the food industry,because palm oil results in adversechanges in the blood concentrations ofLDL and apolipoprotein B just as transfat does10,11,12,13,14.

Conjugated Linoleic acid(CLA)Conjugated fatty acids arepolyunsaturated fatty acids in which atleast one pair of double bonds areseparated by only one single bond, asin conjugated linoleic acid, in Fig. 5,whereas in Fig 4 you will notice thethree double bonds of alpha-linolenicacid (in red) are separated by onefurther carbon, i.e. they are notconjugated.Conjugated linoleic acids (CLA) are afamily of at least 28 isomers of linoleicacid found mostly in the meat anddairy products derived from ruminants(Table 1).

One such isomer of CLA is shown inFig. 5

CLAs are both a trans and a cis fattyacids. The cis bond causes a lowermelting point and ostensibly also theobserved beneficial health effects.Unlike other trans fatty acids, theymay, therefore, have beneficial effectson human health.

In the United States, trans linkages ina conjugated system are not countedas trans fats for the purposes ofnutritional regulations and labelling.

CLA and some trans isomers of oleicacid are produced by microorganismsin the rumens of ruminants (Table 1).

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Figure 3 The structural formulae of two long chain cis 3 fatty acids (EPA& DHA), essential in the diet of vertebrates, including fish and of Man. Thethird is a saturated fatty acid rich in palm oil.

Fig. 4 Reaction scheme for three fattyacids in a molecule of a triglyceride (atriacylglycerol): of trans fat during thehydrogenation process for theproduction of margarine from oils. Upto 45% of the total fat may containtrans fatty acids. The Figure shows atriglyceride containing in one saturatedfatty acid, palmitic acid (blue), onemono-unsaturated fatty acid, oleic acid(green), and one polyunsaturated fattyacid, a-linolenic acid, (red). The latteris changed to a trans.oleic acid*(black), the blue remains palmitic acid;whereas the monounsaturated fattyacid (green) becomes saturated stearicacid (black).*see table 1 below foranother C18:1 acid, Vaccenic acid.

Fig. 5 Conjugated Linoleic acid whichhas adjacent trans7- and cis9-bonds.

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scientificNon-ruminants, including humans,produce certain isomers of CLA from transisomers of oleic acid, such as vaccenicacid (not a conjugated fatty acid, as itpossesses only one double bond, Table 1),but , which is converted to CLA by theenzyme, delta-9-desaturase.

Most studies of CLAs have used a mix-ture of isomers wherein the isomersc9,t11-CLA (rumenic acid) andt10,c12-CLA were the most abundant.More recent studies using individualisomers indicate that the two isomershave very different health effects15,16.

In healthy humans, CLA and the relatedconjugated linolenic acid (CALA) isomersare bioconverted from linoleic acid andalpha-linolenic acid, respectively, mainlyby Bifidobacterium bacteria strainsinhabiting the gastrointestinal tract.

This bacterium is considered to producebeneficial effects, especially in babies. In2008, the United States Food and DrugAdministration categorized CLA asgenerally recognized as safe (GRAS).

Dietary sources of conjugated linoleic acidKangaroo meat may have thehighest concentration of CLA17. Foodproducts from grass-fed ruminants, e.g.mutton, beef18,dairy products and eggsare good sources of CLA19,20.

Some mushrooms, such as Agaricusbisporus and Agaricus subrufescens, are rarenon-animal sources of CLA21.

Health effects of N-6 and N-3polyunsaturated fatty acids (i.e. LA,ALA, EPA and DHA ) andmonounsaturated fatty acids (e.g. oleicacid)The relationship between blood levels ofcholesterol and cardio-vascular disease(CVD), or that between the intake of SFAand PUFA or MUFA and CVD is somewhatinconclusive.

Investigations have failed to show aneffect on flow-mediated dilatation, orother measures of vascular function;whereas significant beneficial effects onblood lipids and slight beneficial effects onblood pressure have been observed byreplacing SFA with either MUFA or PUFA,or by a diet high in carbohydrate22,23,24,25,26,27.

It can be concluded that LC PUFA, (n-6& n-3) and MUFA do benefit blood lipidswhen they replace SFA in the diet; but therelationship between this and risk ofcardio-vascular disease is less clear.

On balance there seems to be a benefitfrom the use of unsaturated fatty acids.

However, it should be borne in mindthat margarines, where the melting pointof unsaturated oils has been raised, maycontain undesirable concentrations oftrans-fatty acids.

When this occurs the beneficial effectcan be nullified. This points to theimportance of declarations on labels ofthe trans-fatty acid content. The onlyreservation to this is the conjugated fattyacids of dairy products, brought about bythe rumen microbial activity, in which themolecule contains both cis and transmodification in adjacent pairs of C atomsin the carbon chain.

The evidence indicates that conjugatedfatty acids are generally recognized assafe.

Health effects of Long chain N-3 fattyacidsThe three types of dietary essentialomega-3 fatty acids involved in humanphysiology are a-linolenic acid (ALA)(found in plant oils)28,29,30,eicosapentaenoic acid (EPA), anddocosahexaenoic acid (DHA) (bothcommonly found in marine oils).

A meta-analysis31 showed a positiverelationship between dietary cholesterolintake and serum cholesterolconcentration; but surveys of any specificrelationship between serum cholesterolconcentration and the incidence ofcardio-vascular disease (CVD) is weak. Thereason for this is that the incidence of CVDis negatively associated with dietary fibreand vegetable protein intake which are alsoinversely associated with cholesterol intake.

The risk of CVD is correlated withsaturated fatty acid intake and theproportion of energy from fat, which inturn is positively associated withcholesterol intake.

Nevertheless, saturated fatty acids arerelatively stable in air, whereas foodscontaining unsaturated fatty acids arevulnerable to oxidation and ranciditywhen exposed to air if the foods areinadequately protected by natural orsynthetic permissible antioxidants.

The results of meta-analyses of surveysand prospective cohort studies indicatethat the consumption of fish or fish oil, inwhich there are high concentrations oftocopherols and other naturalantioxidants protecting the n-3 fatty acids,eicosapentaenoic acid (EPA) anddocosahexaenoic acid (DHA), is associatedwith decreased cardiovascular death,whereas consumption of the vegetableoil-derived n-3 a-linolenic acid isbeneficial, but not as effective31,32,33.

Randomized control trials (RCTs) in thecontext of secondary preventionindicate that the consumption of EPA plusDHA is protective at doses <1 g/d. Thetherapeutic effect appears to be due tosuppression of fatal arrhythmias ratherthan stabilization of atheroscleroticplaques.

At doses >3 g/d, EPA plus DHA can

improve cardiovascular disease risk factors,including decreasing plasmatriacylglycerols (triglycerides), bloodpressure (systolic and diastolic), plateletaggregation, and inflammation, whileimproving vascular reactivity33.

Effects of Omega-3 Fatty Acids onCardiovascular DiseaseMainly on the basis of the results of RCTs,the American Heart Associationrecommends that everyone eat oily fishtwice per week and that those withcoronary heart disease eat 1 g/d of EPAplus DHA from oily fish or supplements34.

Owing to the global scarcity of fish oilsources farmed fish at present contain lessEPA or DHA, than do wild fish.

This situation, we trust, will be rectifiedin due course by the development of agenetically modified Camelinasativa, as a land-based source of EPA andDHA by Haslam et al. (pages15-23).

InflammationSome research suggests that the anti-inflammatory activity of long-chainomega-3 fatty acids may translate intoclinical effects.

A 2013 systematic review foundtentative evidence of benefit35.Consumption of omega-3 fatty acids frommarine sources lowers markers ofinflammation in the blood, such as C-reactive protein, interleukin 6, and TNFalpha.

For rheumatoid arthritis (RA), onesystematic review found consistent, butmodest, evidence for the effect of marinen-3 PUFAs on symptoms such as “jointswelling and pain, duration of morningstiffness, global assessments of pain anddisease activity”35,36.

However, the American College ofRheumatology has stated that there maybe modest benefit from the use of fishoils, but that it may take months foreffects to be seen, and cautions forpossible gastrointestinal side effects andthe possibility of supplements containingmercury or vitamin A at toxic levels37.

Sources of long-chain N-3fatty acidsThe world’s oceans are warming up.

As the mean temperature of oceansrise it decreases their oxygen tensionwith a likely impact on wild fish stocks.

This fact together with over-fishing tomeet the demands of an ever-increasing world human population, isleading to a depletion of these stocks,indicating the essentiality of fishfarming.

Fish, squid and krill are a goodnatural source of N-3 ( -3) fatty acids.

However, these species are unable to

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manufacture long chain N-3 fatty acids(EPA and DHA) to meet their needs.

They depend on marine algae andphytoplankton as the primary sourcesof these fatty acids. These single cellorganisms are the only significantsource of EPA and DHA, required byboth fish and humans, (althoughseveral bacterial genera have beenidentified as sources, e.g. Cellulophaga,Pibocella and Polaribacter in theAntarctic are able to produce EPA &DHA)38. The future of oceanicphytoplankton is unclear, owing toclimate change. There are plantsources of shorter chain N-3 fatty acidse.g. alpha linolenic acid (ALA),including walnut, edible seeds, clarysage seed oil, algal oil, flaxseed oil,Sacha Inchi oil, Echium oil, and hempoil. Fish and eventually Man dependon phytoplankton and the algae forthe synthesis of long chain N-3 fattyacids in quantities to meet theirnutritional requirements.

The ability to transfer phytoplanktongenes for the desaturase and elongaseenzymes for the synthesis of EPA andDHA from shorter chain a-linolenic acidto false flax, described in this issue byHaslam and colleagues at Rothamsted,offers to potentially meet these needswithout further destruction of themarine biosphere.

Omega-3 and omega-9conclusionsOverall, there is strong evidence that fishoils have a beneficial effect on bloodtriglycerides (neutral fat) that is dose-dependent and similar in variouspopulations33,39,40.

There is also evidence of a very smallbeneficial effect of high doses (3-4g/d)fish oils on blood pressure41, especiallythat of DHA42 and possible beneficialeffects on: coronary artery restenosis(stenosis-narrowing of the artery,restricting blood flow) afterangioplasty43,44 and on exercise capacityin patients with coronary atherosclerosis,and possibly heart rate variability,particularly in patients with recentmyocardial infarctions44, 45.

No consistent beneficial effect isapparent for other analysed CVD riskfactors or intermediate markers. However,there is also no consistent evidence of adetrimental effect of omega-3 fatty acidson glucose tolerance. The correlationbetween intake of omega-3 fatty acidsand tissue levels is fairly uniform indifferent tissues46.

Palm oil (from Elaeis guineensis L.)In this Issue we publish a paper on palm

oil which contains approximately 44%palmitic acid and 37% oleic acid.

As palmitic acid is fully saturated, and inan oil, a liquid at room temperature, it ismore stable than many other oils, and soless subject to rancidity; but its saturatednature could have poorer health benefitsthan oils containing polyunsaturated fattyacids. Furthermore, its production has ledto the destruction of vast areas of tropicalforest.

Nevertheless, it contains approximately38% oleic acid, a monounsaturated fattyacid (Table 1), a fatty acid that has someputative health benefits.

Olive oil (from Olea europaea L.)The Mediterranean Diet is one heavilyinfluenced by monounsaturated fats.

People in countries bordering theMediterranean consume more total fatthan those who live in Northern Europeancountries, but most of the fat is in theform of monounsaturated fatty acids fromolive oil and omega-3 fatty acids fromfish, vegetables, and certain meats, whileconsumption of saturated fat is minimal incomparison.

The diet in Crete is fairly high in total fat(40% of total energy, almost exclusivelyprovided by olive oil) yet it affords a

remarkable protection from coronaryheart disease49 (and probably coloncancer) ,owing, possibly to a very higholeic acid content50 (Tables 1 and 2).Much of the benefit may stem from theuse of this oil in its uncooked form byMediterranean countries.

Although olive oil contains oleic acid atlevels of 60-80% a major health benefit isthought to be the non-fat lipids (e.g.0.2% phytosterol and tocosterols,hydroxytyrosol, oleuropein aglycone, andligstroside along with traces of squalene(up to 0.7%) present only in the extravirgin oil). Olive oil is a source of at least30 phenolic compounds, among which iselenolic acid, a marker for maturation ofolives.

The composition of a sample varies bycultivar, region, altitude, time of harvest,and extraction process (Table 2).

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scientific

Table 1 Chemical composition of vegetable oils and butter (Moles %)47

Footnotes* Palm kernel oil is obtained from the kernel of the oil palm fruit.Vaccenic acidv, also known as (E)-Octadec-11-enoic acid is a C18.1 naturallyoccurring trans-fatty acid found in the fat of ruminants and in dairy productssuch as milk, butter, and yogurt. It is also the predominant fatty acidcomprising trans fat in human milk48.

The name was derived from the Latin vacca (cow).

Table 2 Range in fatty acidcomposition of olive oil

CLA (Conjugated linoleic acid)

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scientificAlthough epidemiological studies indicatethat a higher proportion of oleic acid inthe diet may be linked with a reduction inthe risk of coronary heart disease acomprehensive scientific review by theEuropean Food Safety Authority (EFSA)51

in 2011, concluded cause-and-effectrelationships have not been adequatelyestablished for consumption of olive oiland for maintaining 1) normal bloodLDL-cholesterol concentrations, 2) normal(fasting) blood concentrations oftriglycerides, 3) normal bloodHDL-cholesterol concentrations, and 4)normal blood glucose concentrations.

But a large scale KANWU study52 foundthat increasing monounsaturated fat anddecreasing saturated fat intake couldimprove insulin sensitivity, but only whenthe overall fat intake of the diet was low.

Studies have shown that substitutingdietary monounsaturated fat for saturatedfat is associated with increased daily physi-cal activity and resting energyexpenditure53. More physical activity wasassociated with a higher-oleic acid dietthan one of a palmitic acid diet. Inchildren, consumption of monounsaturat-ed oils is associated with healthier serumlipid profiles54.

Limited and not conclusive scientificevidence suggests that eating about 2tbsp. (23g) of olive oil daily may reducethe risk of coronary heart disease owing tothe monounsaturated fat in olive oil. Toachieve this possible benefit, olive oil is toreplace a similar amount of saturated fatand not increase the total daily energyintake. In the United States, producers ofolive oil may place a restricted healthclaim on product labels55.

This decision was announcedNovember 1, 2004, by the Food andDrug Administration after applicationwas made to the FDA by producers.Similar labels are permitted for foodsrich in medium chain omega-3 fattyacids such as walnuts and hemp seed.(A Summary of Qualified Health ClaimsSubject to Enforcement Discretion).

But as mentioned above the lowincidence of heart disease associated witha Mediterranean diet may owe, at least inpart, to the non-fat, lipid constituentspresent only in extra virgin olive oil andthe use of oil in the uncooked form, ratherthan as margarine.

Overall Conclusions1. Vegetable oils are extracted mainlyfrom seeds of: maize, soyabean,sunflower, linseed, rape, olive, andpalm. There is concern over the effectof oil palm plantations on thedestruction of wild life, reduction inbiodiversity and damage to soilcomposition and structure, as well as

the release of greenhouse gases duringthe initial clearance of the plantingarea.2. The yield of oil/ha from thegenetically improved oil-palm is veryconsiderably greater than that, forexample, of olives.3. Vegetable oils provide over twice asmuch net energy/kg compared withstarch and so their consumption cancontribute to obesity with all itsadverse effects on health.4. Vegetable oils are a source of twodietary essential nutrients in the formof the polyunsaturated fatty acids(PUFA), C18:2, 6, linoleic acid andC18:3, 3, a-linolenic acid. Olive oil isalso a rich source of C18:1, 9, oleicacid, a MUFA, which may contribute toits health benefits.5. At present there has been novegetable source of long chain omega-3 dietary essential fatty acids C20:5,3, eicosapentaenoic acid (EPA), andC22:6, 3, docosahexaenoic acid(DHA). Both these omega-3 fatty acidsare essential in the diet of vertebrates,including fish and humans; but theonly major source of them isthe simple oceanic mono-cellularorganisms, phytoplanktons and algae.Haslam et al. at Rothamsted describe inthis Issue, their harvesting from theseorganisms the group of genes neededfor the elongase and desaturaseenzymes necessary for the productionof EPA and DHA from a-linolenic acid,a C18:3, omega-3 acid.They havesuccessfully incorporated these genesin the gene pool of Camelina sativa,false flax, a crop which can be grownin temperate climates. This will be anessential source for fish farming wheretheir current source from wild fish oils,is becoming scarce.6. There is now reasonable evidence thatlong chain omega-3 dietary essentialfatty acids (C20:5, 3 and C22:6, 3),influence risk factors of cardio-vasculardisease (CVD). The best evidence isthat they are more potent than are thedietary essential, a-linolenic acid, anomega-3 acid (C18:3 3), linoleic acidan omega-6 acid (C18:2, 6), or thanoleic acid, an omega-9 acid (C18:9,

1). All these unsaturated fatty acidsare protective, as measured by riskfactors to CVD, response; whereassaturated fatty acids, e.g. palmitic acid(C16:0), are considered to promoteCVD, in comparison to a low fat diet56.Nevertheless, it should be rememberedthat palm oil is rich in both palmiticacid and oleic acid (Table 1). Olive oilcontains a larger proportion of oleicacid and less palmitic acid that doespalm oil, and is considered to be

protective, but the yield per ha of oliveoil is far less than that of palm oilwhich has its environmentalconsequences! (see Murphy pages 24-34). Unsaturated fats are prone tooxidation and rancidity, whereassaturated fats are relatively stable andthe hydrogenation of unsaturatedvegetable oils during the production ofmargarine leads to cis-transisomerisation of unsaturated fats. Thetrans-isomers have been shown to raiseplasma LDL cholesterol levels and topose a risk for CVD. Hence, legislationhas been introduced in the USA, wheretrans-fat levels must be declared on thelabels of appropriate products in theUSA. The relationship of fats to riskfactors of CVD is well established andaccepted. However the correlation ofthese risk factors with the occurrenceof CVD is less well secure57 owing tothe confounding of factors in mixeddiets on the response of individuals.Some clarification of the situation ispossible in the analysis of populationstudies.

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Disease: Implications for Nutrigenetics. J.Nutrigenet Nutrigenomics, 2 (3), 140–148.Published online 2009 Sep 23. doi: 10.1159/000235562 PMCID: PMC282056726 Schwingshackl, L. and Hoffmann, G. (2012)Monounsaturated Fatty Acids and Risk ofCardiovascular Disease: Synopsis of the EvidenceAvailable from Systematic Reviews and Meta-Analyses. Nutrients 4 (12), 1989–2007. Publishedonline 2012 Dec 11. doi: 10.3390/nu4121989PMCID: PMC354661827 Frape, D.L., Williams, N.R., Carpenter K,Freeman, M.A., Palmer C.R. and Fletcher, R.J.(2000) Insulin response and changes incomposition of nonesterified fatty acids in bloodplasma of middle-aged men following isoenergeticfatty and carbohydrate breakfasts. British Journal ofNutrition 84, 737-745.28 Pan A., Chen M, Chowdhury R, Wu J.H, Sun Q,Campos H, Mozaffarian D, Hu FB (2012) a-Linolenic acid and risk of cardiovascular disease: asystematic review and meta-analysis. Am J ClinNutr., 96 (6):1262-73. doi: 10.3945/ajcn.112.044040. Epub 2012 Oct 17.29 Rodriguez-Leyva, D. Bassett, C.M.C.,McCullough, R. and Pierce, G.N. (2010) Thecardiovascular effects of flaxseed and its omega-3fatty acid, alphalinolenic acid. Can J Cardiol. 26(9): 489–496. PMCID: PMC2989356.30 Pan A, Chen M, Chowdhury R; et al. (2012). a-Linolenic acid and risk of cardiovascular disease: asystematic review and meta-analysis. Am. J. Clin.Nutr. (Systematic review) 96 (6): 1262–73.doi:10.3945/ajcn.112.044040. PMC 3497923.PMID31 Marchioli, R. and Levantesi, G.(2013) n–3PUFAs in cardiovascular disease. Proceedings fromthe Round Table on “Current evidence and futureperspectives on n–3 PUFA” London, UK, 2012.International Journal of Cardiology, 170, (2)Supplement 1, S33–S38 Ed. Francesco PellicciaS0167527313X00361-cov150h.gif32. Mozaffarian, D.and,Wu, J. H.Y.(2011) Omega-3 Fatty Acids and Cardiovascular Disease : Effectson Risk Factors, Molecular Pathways, andClinical Events. Journal of the American College ofCardiology, 58, (20), 2047–2067.33 Anon. Agency for Healthcare Research andQuality ( AHRQ) U.S. Departmentof Health &Human Services (2004) Effects of Omega-3 FattyAcids on Cardiovascular Disease Evidence Report/echnology Assessment: Number 94.www.ahrq.gov., www.hhs.gov AHRQ, ArchivedEPC Evidence Reports, Publication No. 04-E009-2March 200434 Anon. The American Heart Association (2015)Eating fish for heart health, Tweet 29, updated15th May,2015, 7272 Greenville Ave. Dallas, TX75231, Customer Service, 1-800-AHA-USA-1, 1-800-242-872135. Di Giuseppe, D., Wallin, A. Bottai, M., Askling,J. and Wolk, A. (2013) Long-term intake of dietarylong-chain n-3 polyunsaturated fatty acids andrisk of rheumatoid arthritis: a prospective cohortstudy of women Ann Rheum Dis doi:10.1136/annrheumdis-2013-203338 Clinical andepidemiological research36 Calder PC (2008). Symposium on ‘Nutritionand autoimmune disease’ PUFA, inflammatoryprocesses and rheumatoid arthritis. Proc Nutr Soc.67 (4), 409-18. doi: 10.1017/S0029665108008690. Session 3: Joint Nutrition Societyand Irish Nutrition and Dietetic Institute37 Geusens P., Wouters, C. Nijs, J.,Jiang Y. andDequeker J.(2005) Long-term effect of omega-3fatty acid supplementation in active rheumatoidarthritis Arthritis & Rheumatism 37, (6), 824–829,Article first published online: 9 DEC 2005 DOI:10.1002/art.1780370608 Copyright © 1994American College of Rheumatology.38 Bianchi, A. C., Olazábal, L, Torre, A. andLoperena, L (2014) Antarctic microorganisms as

source of the omega-3 polyunsaturated fatty acid.World Journal of Microbiology and Biotechnology. 30(6) 1869-1878. First online: 29 January 2014.39 Svensson M., Christensen J.H., Sølling J.,Schmidt E.B.(2004) The effect of n-3 fatty acids onplasma lipids and lipoproteins and blood pressurein patients with CRF. Am J Kidney Dis. 44 (1) 77-83.40 Boberg M., Pollare, T., Siegbahn, A., Vessby, B.(1992) Supplementation with n-3 fatty acidsreduces triglycerides but increases PAI-1 in non-insulindependent diabetes mellitus. Eur J ClinInvest. 22 (10), 645-50.41. Massaro, M., Scoditti, E., Carluccio M.A.,Campana M.C. and De Caterina, R. (2010)Omega-3 fatty acids, inflammation andangiogenesis: basic mechanisms behind thecardioprotective effects of fish and fish oils. CellMol. Biol. (Noisy-le-grand). 56, (1), 59-82.42 Mori T.A., Bao D.Q., Burke V, Puddey I.B. sndBeilin L.J. (1999) Docosahexaenoic acid but noteicosapentaenoic acid lowers ambulatory bloodpressure and heart rate in humans. Hypertension.34 (2), 253-60.43 Dehmer, G.J., ,Popma,J.J.,van den Berg, E.K..,Eichhorn, E.J.,Prewitt, J.B.,. Campbell, W.B. et al..,(1988) Reduction in the Rate of Early Restenosisafter Coronary Angioplasty by a DietSupplemented with n–3 Fatty Acids. N Engl JMed, 319, 733-740. DOI: 10.1056/NEJM19880922319120144 Balk, E.M, , Lichtenstein, A.H., Chung, M,Kupelnick, B., Chew P and Lau, J. (2006) Effects ofomega-3 fatty acids on coronary restenosis,intima– media thickness, and exercise tolerance: Asystematic review. Atherosclerosis 184 ,(2), 237–246.45 Anon. (2004) U.S. Department of Health &Human Services, www.hhs.gov; Agency forHealthcare Research and Quality AHRQ, ArchivedEPC Evidence Reports Effects of Omega-3 FattyAcids on Cardiovascular Risk Factors andIntermediate Markers of Cardiovascular DiseaseEvidence Report/Technology Assessment: Number9346 Garneau,V., Rudkowska, I,, Paradis, A.M.,Godin, G., Julien, P., Pérusse, L., and Vohl, M.C.(2012) Omega-3 fatty acids status in humansubjects estimated using a food frequencyquestionnaire and plasma phospholipids level.Nutr J.,11, (46), doi: 10.1186/1475-289.47 Anon. (1976) online edition: Fat Content andComposition of Animal Products, Nutrientdatabase, Release 24. United States Department ofAgriculture. Publishing Office, National Academy ofScience, Washington, D.C., ISBN 0-309-02440-4;p. 203.48 Friesen, R., and Innis, S.M. (2006) Trans Fattyacids in Human milk in Canada declined with theintroduction of trans fat food labeling, J. Nut.,136, 2558-2561).49. Guasch-Ferré, M., Hu, F.B., Martínez-González,M.A., Fitó, M., Bulló,M, Estruch,R, Ros, E., CorellaD. et al, (2014) Olive oil intake and risk ofcardiovascular disease and mortality in thePREDIMED Study. BMC Medicine, 12, (78)doi:10.1186/1741-7015-12-7850 León, L., Uceda, M., Jiménez, A., Martín, L.M.and Rallo, L. (2004) Variability of fatty acidcomposition in olive (Olea europaea L.)progenies. Spanish Journal of Agricultural Research2 (3), 353-35951 Anon. Scientific Committee/Scientific Panel ofthe European Food Safety Authority. (2011)Scientific Opinion on the substantiation of healthclaims related to olive oil and maintenance ofnormal blood LDL-cholesterol concentrationsEFSA Journal (European Commission) 9 (4), 2044[19 pp]. doi:10.2903/j.efsa.2011.2044. RetrievedApril 5, 2013.52 Vessby B, Uusitupa M, Hermansen K, RiccardiG, Rivellese A .A, Tapsell L .C, Nälsén C, Berglund

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scientificL, Louheranta A, Rasmussen B .M, Calvert G .D,Maffetone A, Pedersen E, Gustafsson I .B, StorlienL .H. (2001) Substituting dietary saturated formonounsaturated fat impairs insulin sensitivity inhealthy men and women: The KANWU Study.Diabetologia,.44 (3), 312-9.53 Kien, C.L., Bunn, J.Y., Tompkins, C.L., Dumas,J.A., Crain, K.I., Ebenstein, D.B., Koves, T.R. andMuoio, D.M. (2013). Substituting dietarymonounsaturated fat for saturated fat isassociated with increased daily physical activityand resting energy expenditure and with changesin mood. The American Journal of Clinical Nutrition97 (4), 689–697. doi:10.3945/ajcn.112.051730.

PMID 23446891).54 Sanchez-Bayle M., Gonzalez-Requejo A., PelaezM.J., Morales M.T., Asensio-Anton J. and Anton-Pacheco E. (2008). A cross-sectional study ofdietary habits and lipid profiles. The Rivas-Vaciamadrid study. Eur. J. Pediatr. 167 (2), 149–54.doi:10.1007/s00431-007-0439-6. PMID17333272.).55 U.S. Food and Drug Administration (2004)Monounsaturated Fatty Acids From Olive Oil andCoronary Heart Disease. Summary of QualifiedHealth Claims Subject to Enforcement Discretion.Docket No. 2003Q-0559 11/01/2004enforcement discretion letter.

56 Frape, D.L., Williams, N.R., Rajput-Williams, J.

Maitland, B.W., Fletcher, R.J. and Palmer, C.R.

(1998). Circadian variation in blood thrombogenic

characteristics in middle-aged healthy men given

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Introduction

In 2010, fish accounted for around17% of the global population’sintake of animal protein and almost

7% of all protein consumed (1). As well as being an important dietary

sources of protein, minerals andvitamins (2), fish and seafood are alsothe major sources of long chain (LC)omega-3 polyunsaturated fatty acids,particularly eicosapentaenoic (EPA;

) and docosahexaenoic (DHA;) acids (3), that have well-

known beneficial effects in humanhealth, including cardiovascular andinflammatory diseases, and importantroles in neural development (4,5).

However, global marine fisheries arestagnating and over 60% of fish stocksrequire rebuilding (6) so that anincreasing proportion of fish are

farmed, reaching almost 50% in 2012(1). Paradoxically, feeds for manyfarmed fish species are dependent onfishmeal and fish oil, themselvesderived from marine fisheries, for thesupply of LC omega-3 (7). Reliance onfinite marine resources was anunsustainable practice (8) and thecontinued growth of aquaculture hasbeen dependent upon thedevelopment of more sustainable feedswith alternative ingredients, generallyderived from terrestrial agriculture, thatlack LC omega-3 (9).

This has important consequences forthe supply of these nutrients to humanconsumers and so there has been aglobal drive to find alternative suppliesof LC omega-3 fatty acids foraquaculture (10).

The most promising and viable

option for entirely new sources of LComega-3 are transgenic oilseed crops.

2. Long chain omega-3and human healthIt has long been appreciated thatdietary LC omega-3 can haveimportant, generally beneficial effectson human health (11).

The strongest evidence has beenfound in relation to heart andcardiovascular disease (CVD) (12);today a large number of nationalhealth agencies and governmentbodies recognize the importance ofincreasing dietary intake of EPA andDHA to promote cardiac health anddecrease the risk of CVD (12,13).

Recently, the current advice andguidelines worldwide were compre

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The supply of fish oil toaquaculture: a role for

transgenic oilseed crops?Richard P Haslam1, Sarah Usher1, Olga Sayanova1, Johnathan A Napier1,

Monica B Betancor2, Douglas R Tocher2

1 Biological Chemistry & Crop Protection, Rothamsted Research,Harpenden, Hertfordshire, AL5 2JQ, UK.

2 Institute of Aquaculture, School of Natural Sciences, University of Stirling,Stirling FK9 4LA, Scotland, UK.

Authors for correspondence: Richard Haslam, richard.haslam@rothamsted.ac.uk;Douglas Tocher, d.r.tocher@stir.ac.uk

SummaryThe importance of an alternative and sustainable supply of omega-3 long chain polyunsaturated fatty acids (LC omega-3)has long been established. As these biologically active fatty acids have a role in nutrition and health, there is an everincreasing demand for oils containing LC omega-3 e.g. eicosapentaenoic (EPA) and docosahexaenoic acid (DHA). Thesefatty acids are produced by micoroganisms and enter our diet through the consumption of fish. However, in order that thenutritional requirements of fish in aquaculture are met and sufficient levels are deposited to meet the requirements ofhuman consumers, EPA and DHA must be supplied in excess. Given the importance of the aquaculture industry in deliveringhealthy foodstuff, the question of how to resource the supply of LC omega-3 then arises; traditional sources of EPA and DHA(fish oil) are challenged, whilst vegetable oils do not contain EPA or DHA. Therefore research efforts have focused on thesuccessful reconstitution of LC omega-3 biosynthesis in oilseed crops. The production of EPA and DHA in the seed oil ofagricultural crops has the capacity to deliver large volumes of these fatty acids. The expression of optimised combinations ofthe genes required to produce these fatty acids in the seed of the crop Camelina sativa has been achieved and the utility ofthis approach demonstrated. This represents a significant breakthrough – the provision of an effective alternative to the useof omega-3 fish oil by the global aquaculture industry.

Key words Aquaculture; fish oil; nutrition; metabolism; sustainability; GM plants; Omega-3; plant biotechnology

AbbreviationsCVD, cardiovascular disease; DHA, docosahexaenoic acid (22:6n-3); EFA, essential fatty acid; EPA, eicosapentaenoic acid (20:5n-3);FM, fishmeal; FO, fish oil; GM, genetically modified; LC-PUFA, long-chain polyunsaturated fatty acids (≥C20 ≥ 3 double bonds);LC omega-3, LC-PUFA predominantly EPA and DHA; MT, metric million tonnes; TAG, triacylglycerol; VO, vegetable oil.

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hensively reviewed (14) andrecommendations of over 50organisations were compiled by theGlobal Organisation for EPA and DHA(15). Most recommendations suggestbetween 250 and 500 mg/d of EPAand DHA for reducing CVD risk or 1g/d for secondary prevention inexisting CVD patients, with a dietarystrategy for achieving 500 mg/d beingto consume two fish meals (200 –250g) per week with at least one ofoily fish (14,16,17) (Table 1).

In addition to cardiac health andCVD, dietary LC omega-3 can bebeneficial in several other pathologieswith the most robust evidence forinflammatory diseases obtained inrheumatoid arthritis, in which the doserequired to gain benefit is set higherthan for CVD (around 3g per day(18)). There is also increasing evidencefor beneficial effects of dietary LComega-3 in Inflammatory BowelDiseases (IBD) such as Crohn’s diseaseand ulcerative colitis (19).

The effects of dietary LC omega-3 oncancers has been more controversial.Epidemiological studies indicated that,in general, dietary LC-omega-3 maydecrease risk of colo-rectal, breast andprostate cancers (20) and some studiessuggest beneficial effects inchemotherapy (21).

However, one research groupsuggested that LC-omega-3 may beassociated with increased risk ofprostate cancer (22,23); althoughlatterly a second systematic review andmeta-analyses of all studies concluded

that the results did not support anassociation between LC omega-3 andprostate cancer (24). With regard todevelopment, there is robust evidencethat decreased DHA status can lead tocognitive and visual impairment andthat DHA supplements have positivebeneficial outcomes in pre-term infants(25). There have also been severalreports of potential beneficial effects ofdietary DHA supplementation in anumber of psychological/behavioural/psychiatric disorders includingattention deficit hyperactivity disorderand depression, although there areinsufficient studies and data to drawfirm conclusions (26). However, it isbecoming generally recognised that LComega-3 are potential key nutrients toprevent various pathological conditionsassociated with the normal agingprocess (27), which has promptedresearch into the effects of LC omega-3on dementia, including Alzheimer’sdisease and other age-related cognitiveimpairments (28). In general, DHAsupplementation trials in patients withsome pre-diagnosed cognitiveimpairment indicated that thisappeared to slow progression ofAlzheimer’s (29).

3. Aquaculture: require-ment for LC omega-3Vertebrates, including fish, cannotsynthesise polyunsaturated fatty acids(PUFA) because they lack the enzymesrequired for their production frommonounsaturated fatty acids and sothey are essential in the diet.

Terrestrial plants can be rich inmedium chain PUFA such as linoleicacid ( ) and linolenic acid (LNA,

), but the biologically activefatty acids in fish are the long-chainPUFA, primarily EPA and DHA. Somefreshwater and salmonids species of fishcan produce EPA and DHA from LNA,but most marine fish cannot. Inconsequence, which PUFA can satisfythe essential fatty acid (EFA)requirements in fish vary with species(30,31). The actual EFA requirement infish can be described at three levels.The amount of EFA a fish requires toprevent nutritional pathology is low,often around 1% of the diet (30,31).

However, a higher level of EFA may berequired to support optimum growthand health, which is similar to thesituation in humans where few peoplesuffer from EFA deficiency but, rather,LC omega-3 is required for optimaldevelopment and health. The final EFArequirement level in fish is that tomaintain nutritional quality based on LComega-3 content of the flesh (9). Assuch, this is not a requirement of thefish, but rather that of humanconsumers (32). To satisfy this level, EPAand DHA need to be supplied to thefish well in excess of the requirementsfor optimal health and growth so thatthey are deposited and stored in thefish. For example, to produce farmedsalmon with the level of EPA and DHArequired to supply the weekly humanrequirement of 3.5g in one 130gportion, it would be necessary for EPAplus DHA to be at 6-7% of diet (33).

Table 1 International recommendations for dietary long-chain n-3 LC-PUFA consumption in humans. ALA, linolenic acid;DHA, docosahexaenoic acid; EPA, eicosapentaenoic acid; FAO, Food and Agriculture Organization; ISSFAL, InternationalSociety for the Study of Fatty Acids and Lipids; NATO, North Atlantic Treaty Organization; WHO, World Health

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This level of supplementation wouldmake fish-farming commerciallyuneconomical.

4. Fish OilIn 2013 around 75% of total globalfish oil supply was used in aquaculture,with 83% of that consumed bysalmonids (60%) and marine fish(23%), and a further 21% used fordirect human consumption (34)

(Figs.1A &B). Despite continued growth of

aquaculture (1), the use of fish oil forfeeds has been relatively stable overthe last decade with, on average,around 0.8 million metric tonnes (Mt)being used (34) (Fig.1C). The primaryconstraint with fish oil is that it is afinite resource with production limitedthrough strict regulation of fishing andcatch quotas (35,36). Althoughproduction of fish oil has declined inrecent years, largely due to regulationand quotas in South America (37), thishas been partially offset by increaseduse of seafood and aquaculture by-products including by-catch andtrimmings to produce fish meal and, toa lesser extent, fish oil (36).

However, fish oil production averagesaround 1 million Mt annually andthere is little to no prospect of thatincreasing.

Production of fish oil is also subjectto environmental influences and acutephenomena such as El Niño have well-known consequences, considerablyreducing supply (38). Sustainabilityissues are also key drivers limiting fishoil supplies, and these will have anincreasing impact with the many

initiatives currently being developedwith respect to both national andinternational standards andcertification of marine ingredients,including fish oil (33).

Although increasing adoption andimplementation of these standards willfurther improve sustainability, they will

likely have impacts on the availabilityof fish oil and its use in aquaculture.

A further factor constraining the useof fish oil is the presence ofcontaminants/undesirables such aspersistent organic pollutants (POPS)including dioxins and PCBs (9,39).With some fish oils, such as those from

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Figure 1. Global Consumption and supply of fish oil. In 2013 around 75% of totalglobal fish oil supply was used in aquaculture, 83% of that consumed bysalmonids (60%) and marine fish (23%), and 21% went human consumption (a& b). The use of fish oil for feeds has been relatively stable over the last decade

on average around 0.8 million metric tonnes (34) (c).

Table 2. World oil and fat productionin 2012 (a).a http://lipidlibrary.aocs.org/market/ofo6-07.htm (Updated 03/2013;

Table 3. Fatty acid (FA) composition (Mol%) of major vegetable oils and animalfats. *Sat.,saturated FA; Mono., monounsaturated FA

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the Baltic, levels can be higher thanpermitted for use in animal feeds andthese require decontamination beforethey can be used.

However, this is an issue that hasbeen diminishing to some extent withthe increasing replacement of dietaryfish oil and as a result levels of theseundesirable marine environmentalcontaminants in feeds are decreasing(40). To put demand for fish oil (viz.LC omega-3) for aquaculture intoperspective, to supply the salmonindustry alone would require morethan 1 million Mt annually (i.e. greaterthan the average global supply).

Thus the only way aquaculture hascontinued to grow has been byincreasing substitution with alternativeoils (10). Global oil and fat productionwas more than 185 million Mt in2012, with total production ofvegetable oils at over 160 million Mt,and animal fats including tallow, lardand butter totalling another 25 millionMt. Thus, alternative oils are plentifulalthough they all lack LC omega-3(Table 2). Terrestrial plants do not

produce EPA and DHA and so they arenot components of any vegetable oil,whilst animal fats are dominated bysaturated and monounsaturated fattyacids with only low levels of PUFA(Table 3).

The consequence of this has been theincreasing substitution of fish oil withalternative oils, effectively spreadingthe available fish oil thinner in thefeeds, which has inevitably led to areduction in LC omega-3 levels in bothfeeds and farmed fish (10) (Table 4).

However, the issues surrounding thelimited supply of LC omega-3transcend aquaculture. Based on themost commonly recommended dosefor cardiac health (500 mg/day (15)),the demand for LC omega-3 is over1.25 million Mt whereas global supplyis optimistically estimated at just over0.8 million Mt indicating a shortfall ofover 0.4 million Mts (41) (Table 5).

The majority of supply (almost 90%)is from capture fisheries, whether asfood fish or via fish oil and meal, withsmall additional amounts estimatedfrom seafood by-products, unfed

aquaculture and algal sources.The calculations in Table 5 contain

assumptions and estimates and so theprecise extent of the difference can bethe argued, however, that there is agap between supply and demand isnot in question irrespective of how it iscalculated (42).

There is a fundamental, global lack ofLC omega-3 to supply human needs,whether by direct consumption or viaaquaculture.

5. Alternative sources ofomega-3 LC-PUFAThere is an urgent need for alternativesources of the LC omega-3, EPA andDHA (41).

As the primary producers of almost allLC omega-3 are marine microalgaeand bacteria, the only alternatives totraditional fish oil are other oils sourcedfrom the marine environmentincluding lower trophic levels (zoo-plankton), mesopelagic fish, by-catch/by-products and microalgae them-selves.

Lower trophic levels Zooplankton such as krill and calanoidcopepods in the southern andnorthern hemispheres, respectively, arepossible options but, although biomassat lower trophic levels is large, thereare inherent dangers associated withfishing down the marine food web(43).

Potentially, zooplankton can be goodoil sources, but harvesting of krill andcopepods poses significanttechnological challenges and cost (44).For most species, lack of schoolingbehaviour makes harvest by traditionaltrawling technology an expensiveeconomic option (44). Antarctic krill,which do form schools, are the onlyspecies being targeted for commercialharvest, apart from a small scientificquota (~1000 Mt) of the calanoidcopepod, Calanus finmachicus (45).

Krill meals, that contain residual oiland therefore some LC omega-3, arecurrently used in some premium feedsfocussed on health benefits and aregenerally used sparingly. These krillmeals are therefore not being used asprimary sources of LC omega-3 and,currently, krill oils are used almostexclusively for the human nutraceuticalmarket. Although there may beevidence that harvesting krill, andpotentially copepods, could besustainable, there are still significantenvironmental and ecological concerns(44). For instance, Antarctic krill arenear the base of a food chain that

Table 4 Effect of complete or partial replacement of dietary fish oils by vegetableoils on fatty acid compositions (percentage of weight of total lipid) of flesh ofAtlantic salmon. FO, fish oil; LO, Linseed oil; PO, palm oil; RO, rapeseed (Canola)oil; SO, sunflower oil; VO, vegetable oil blend.Details of fish initial weight, extentof dietry replacement and length of feeding trial are provided: a Initial wt. 55 g /100 % replacement / 30 weeks, b Initial wt. 80 g / 100 % replacement / 17 weeks, cInitial wt. 22 g / 100 % replacement / 9 weeks, d Initial wt. 127 g / 100 % replace-ment / 40 weeks), e Initial wt. 0.16g / 100 % replacement, RO/PO/LO [3.7:2:1] / 22months.

a ROb c d e

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includes whales and penguins,suggesting there could be damage tomarine biodiversity (46).

Mesopelagic fishMesopelagic fish that inhabit theintermediate pelagic water massesbetween the euphotic zone at 100mdepth and the deep bathypelagic zoneat 1000m are available in potentiallylarge quantities (1-6 billion Mt), withlantern fish, myctophids, constitutingabout 60% of biomass (47).

Different species can contain between16 and 60% of dry weight (48) as oiland most are potentially good sourcesof LC omega-3 (44). On the positiveside, they are resources that, so far,have not been the subject ofcommercial exploitation, and they donot compete with existing or potentialhuman feed production.

Negative points include biological(seasonal variation), ecological (mixedfishery difficult to manage), technical(capture methods and on-boardprocessing), and nutritional issues.

By-catch and seafood processingby-products In almost all fisheries there are non-

target catch and/or discarded targetcatch that, together, make up theby-catch. However, both the precisedefinition and resultant estimates ofby-catch can be controversial (49).

In 2005, the discard rate wasestimated at around 7 million Mt/yearor 8% of the global catch (50). By itsnature, by-catch is a diffuse resource(51) and this imposes a majorlimitation to its usefulness as a sourceof fish oil, although processing ofby-products, including oil production,at sea is an increasing trend (52).Another limitation is that by-catchincludes a multitude of species, notnecessarily “oily”, which limits thequantity and quality of the oilsproduced (51).

Seafood industry by-productsincluding viscera, heads, carcasses andtrimmings, particularly those producedfrom pelagic fisheries and aquacultureare another potential source of marineoil although this is largely dictated byspecies. Thus, by-products from oilyspecies including salmon, herring andmackerel can be a source of substantialoil whereas by-products from otherpelagic (white fish) fisheries havegenerally low oil contents (53).

Liver from species like cod andhalibut have traditionally been used forfish oil production, but production isnow relatively small (~ 40,000 Mt) andgoes mostly for direct humanconsumption as vitamin supplementsas much as sources of LC omega-3(54). Oil is now being activelyrecovered from aquaculture specieswaste, particularly salmon farming,with around 20,000 Mt reportedlyrecovered in Norway (55) and 50,000Mt in Chile in 2006 (56).

Marine microalgae Potentially, culture of the main primaryproducers, marine microalgae, couldoffer a long-term solution to thesustainable supply of LC omega-3 (57).Various photosynthetic microalgae arealready commonly used in fishhatcheries to supply both EPA (e.g.diatoms) and DHA (e.g. flagellates) inthe rearing of larval marine crustaceanand fish species (58). Productionusually employs medium- to high-density batch, semi-continuous orcontinuous culture in relatively smallvolumes (59).

Up-scaling of production to thevolumes required for algal oil and/oralgal biomass to supply the amount ofLC omega-3 required to replace fish oilin commercial aquafeed productionhas significant biological andtechnological challenges (60).Economic production of LC omega-3would require algae to demonstratesimultaneous high growth and high oilcontent with high proportions of EPAand DHA. These are almost exclusivetraits as oil deposition is usuallyassociated with conditions which occuronly when growth is limited (e.g.nitrogen limitation) (61).

Technical challenges include efficientcapture of light energy in high-densityculture with effective temperaturecontrol. These issues remain to besolved but there are several researchstrategies targeting their solution.

These include exploiting cultureconditions to direct metabolismtowards lipid production, to improvebiomass productivity or oil yield bymutagenesis and selective breeding,and to improve strains by geneticmodifications to optimize lightabsorption and increase biosynthesis ofEPA and DHA (60). Therefore, in thefuture, algal species with favourablebiological characteristics may be foundand/or developed, and photo-bioreactor technologies may improveconsiderably enabling economicallysustainable production of microalgaerich in EPA and DHA for use in

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Table 5. Potential annual demand for n-3 LC-PUFA based on recommended intakefor reduction of risk of cardio-vascular disease compared with global annualsupply from major sources. Production figures are from 2012 (FAO, 20141). Alllipid and n-3 LC-PUFA contents/yields are estimated averages over the widerange of species in each category. 1Salmonids include salmon and trout spp.Freshwater species includes eels, tilapia and other freshwater species that stillutilise some fishmeal and fish oil (13% of total fish oil used in aquaculture) infeeds. NA, not available. Although there will be some endogenous production ofn-3 LC-PUFA inversely related to fishmeal and oil contents of feeds, this cannotbe accurately estimated, but will likely be minor based on volume of fish oilconsumed by these sectors (75% of all fish oil used in aquaculture).

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scientificaquafeed. In contrast, heterotrophicmicroalgae species includingCrypthecodinium and thraustochytridssuch as Schizochytrium are alreadybeing utilised for the commercialproduction of DHA using large-scalebiofermentor technology (62). Even so,the high production costs are generallylimiting the use of these products todirect human consumption mainly inthe form of DHA supplementation ofinfant formulae (63).

However, the DHA-rich products fromheterotrophic microalgae may haveniche markets in marine hatcheries,particularly for high-value species.Production volumes would have to beincreased and costs reduced beforethese products could be viable forwider application in aquaculture.

6. Plants as a source ofomega-3 LC-PUFAIt has long been the hope ofresearchers in the field of plant lipidbiotechnology to produce a terrestrialsupply of vegetable oil with acomposition (EPA/DHA) matching thatof fish oil.

However, metabolic engineering onthis scale is not trivial. Synthesis of LComega-3 commonly occurs in marinemicroalgae via a series of sequentialaerobic desaturation and elongationreactions.

These reactions typically follow tworoutes – the ‘D6 pathway’ (Fig 2a)beginning with the D6-desaturation ofthe C18 substrate, C2 elongation andD5-desaturation or the much rarer ‘D8pathway’ where the C18 substrateundergoes a C2 elongation, followedby two rounds of desaturation.

To then generate DHA in eitherpathway requires a further C2elongation and desaturation.

Through whichever aerobic route, aminimum of three genes are requiredto synthesise EPA and five for DHAproduction. A further anaerobic routeto LC omega-3 has been identified insome bacteria and unicellular marineeukaryotes and functionallycharacterised; this pathway uses aprocessive polyketide synthase-likeenzymatic system to convertmalonyl-CoA to EPA and DHA with theproduction of no intermediates(64,65). The activities and genes foreach of the biochemical routes to LComega-3 FA production have beencharacterised and are available for useby the metabolic engineer to reconsti-tute EPA/DHA synthesis in a suitableheterologous host (64).

However, success can only be

achieved by addressing somesignificant challenges: (1) the C18 di-or tri-unsaturated substrate must bepre-existing; (2) reconstitution of thepathway in a specific tissue (e.g. seed)requires the co-ordinated and targetedexpression of multiple genes andactivities; (3) the production of novelLC omega-3 and their correctacyl-exchange between lipid poolsdepends on the capacity of nativeendogenous enzymes that areunfamiliar with the fatty acids; and (4)the processes underpinning thebiochemical acyl-exchange or flux offatty acids between lipid species withinplant cells is only now starting to beappreciated.

It is entirely possible for biosyntheticintermediates to be channelled into‘metabolic cul-de-sacs’ rendering themunavailable for further desaturation,elongation or storage in seed oil (65).

Historically, many of the individualgenes necessary for LC omega-3production were individuallycharacterised in plants, indicating thatin combination they would besuccessful. The first demonstration ofEPA production in a transgenic plantwas published by Qi et al. (66)

expressing the algal alternativepathway in the leaves of Arabidopsisthaliana. The approach used a series ofsequential transformations of individualgenes and resulted in the vegetativeaccumulation of EPA, predominantly inphospholipids. To be of economicvalue in the context of aquaculture asdescribed above, it is necessary to havean engineered oilseed crop where thetarget LC omega-3 would be producedand stored in the neutral lipids(triacylglycerol) of seeds at high levels.The possibility of LC omega-3biosynthesis targeted to seeds wasshown by Abbadi (67) in which the

conventional D6 pathway wasexpressed in transgenic linseed.

Abbadi (67) identified the presence oflow levels of EPA in seeds, butconcomitant with high levels of C18D6-intermediates.

The un-wanted intermediates werethe result of the poor acyl-exchange ofintermediates between the acyl-CoApool (elongation) and glycerolipid pool(desaturation). Following these proof-of-concept studies efforts havecontinued to drive up theaccumulation of LC omega-3 in seedoil and reduce the presence ofintermediates e.g. D6 desaturationproducts like linolenic acid.

Such iterative engineering followedtwo strategies, the first utilised byPetrie and co-workers (CSIRO) madeuse of Agrobacterium-mediatedtransient expression of multiple genecombinations in Nicotiana benthamiana(68). Although testing was undertakenin leaves, the co-expression of the Lec2transcription factor or master regulatoressentially ‘reprogrammed’ the leaf toreplicate the lipid composition of aseed; a system that permitted the rapidselection of optimal genecombinations. The second approach,adopted by Heinz et al. (University ofHamburg) and Napier et al.(Rothamsted Research) was to directlyassess gene combinations and theirregulatory elements in the seeds ofstably transformed plants (namely theoilseed model A. thaliana) (69,70).

In combination with the developmentlipidomic approaches, it then enabledthe evaluation of gene combinationefficacy in the seed. Critical to theprogress of these efforts was the use ofomega-3 desaturases (reducing theaccumulation of un-wanted omega-6fatty acids) and the use of acyl-CoAdependent desaturases (breaking the

Figure 2. The biosynthesis pathway of LC omega-3 in Camelina. (a) Schematicrepresentation of the enzymatic steps involved in the synthesis of LC omega-3fatty acids; total fatty acid composition of generic fish oil (b) and an individualseed of GM Camelina (72).

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desaturase/elongase substratedichotomy) (65).

7. Transition to cropsAs described, the majority of thesystematic work undertaken toproduce a seed oil composition akin tofish oil (i.e. ~20% EPA and DHA in totalfatty acids) was undertaken in modelplant species i.e. arabidopsis andtobacco.

However, to produce the volumes ofLC omega-3 required by aquaculturenecessitates the production of EPA andDHA in agricultural oilseed crops. Theopportunities of scale associated withsuch crops provide the only chance togenerate a fish oil substitute insignificant quantities. From theavailable oilseed crops, screening hasidentified two as appropriate hosts forthe production of LC omega-3; the firstcanola, a cultivar of rapeseed (Brassicanapus L.) and secondly Camelina(Camelina sativa L). At this time nopublic data are available to assess theexpression of the LC omega-3 trait incanola. However, two laboratories(Rothamsted and CSIRO) havedemonstrated the success of Camelinaas a host for the accumulation of EPAand DHA in seed oil (71,72). Camelinais an oilseed crop of the Brassicaceaeadapted to temperate growingregions, with a low input requirement,short crop cycle and disease resistance.In terms of performance, Camelina hasan acceptable yield (levels over 3000kg/ha have been achieved) with an oilcontent of ~40%.

Of interest to metabolic engineers,Camelina is an excellent platform forthe production of tailored oils; it hasvery low outcrossing levels, and fullydeveloped tools for breeding andmolecular trait improvement due tothe high sequence identity withArabidopsis. Furthermore, genetictransformation is possible usingAgrobacterium-mediated floral dip.

However, it is the unique fatty acidcomposition of Camelina (unusual for aBrassicaceae the polyunsaturatedlinolenic acid (18:3) and linoleic acid(18:2) – substrates for LC omega-3synthesis – are the major fatty acids,whilst erucic acid (22:1) is low) thatengenders this host to geneticengineering approaches (73).

Although different approaches weretaken by Rothamsted and CSIRO, bothdemonstrated the suitability ofCamelina as a host for the productionof LC omega-3 in seeds. Researchers atRothamsted used knowledge acquiredfrom earlier engineering in Arabidopsis,introducing two optimised constructs

into Camelina – one producing EPAalone and the other making both EPAand DHA. Analysis of the seed fattyacid composition from the stabletransgenic lines revealed the averagelevel of EPA alone was 24%, and forEPA and DHA, 11 and 8% respectively(72). Significantly in both constructsonly very low levels of C18intermediates were recorded. Overall,the average total level of LC omega-3was 19% (EPA + DHA) and muchhigher (25%) in some single seeds (seeFig 2) (72). The reported work fromCSIRO showed significantaccumulations of DHA with all theintroduced constructs (12% withconstruct combination GA7 andmod-F), however levels of EPA werelow (~3% for mod-F) (71). Thedifferences in the accumulations of LComega-3 in Camelina can be attributedto a number of factors e.g. selection ofseed-specific promoter, choice ofCamelina variety, activity of eachenzyme choice, constructs design/orientation, and possibly site ofintegration. For example, it is likelythat the use of a highly active D5-elongases resulted in the specificdifference in EPA accumulation (65).

Moreover, field evaluation of the LComega-3 trait (EPA + DHA) in Camelinawas undertaken at Rothamsted, wherethe feasibility was demonstrated (bycomparison to replicated glasshouseexperiments) of producing LC omega-3 in the field without any yield penalty(74). Thus, the choice of the oilseedcrop Camelina as a host for thesuccessful expression of the LC omega-3 trait has been established.

8. Utility of Camelina LCOmega-3 Oil inAquacultureThe essential question must be; canthe novel LC omega-3 oils generatedin Camelina be used as a substitute forfish oil?

To address this Betancor et al. (75)

recently completed a study in whichthe EPA-containing Camelina oildescribed by Ruiz-Lopez et al. (72) wastested as a substitute for fish oil in asalmon feeding trial. In this study, fishoil (control), wild type (WT) and EPA-containing Camelina oil (GM) were fedto juvenile Atlantic salmon within aniso-energetic diet for a period of sevenweeks.

At the end of the feeding trial all thefish had doubled in weight anddisplayed no indicators of ill health;moreover fatty acid analysis indicatedthe expected accumulation of EPA (as a

result of slow EPA conversion, levels ofDHA in tissues were also shown to beincreased).

Further transcriptomic analysisproduced a similar pattern of gene upregulation in fish receiving WT and GMCamelina oil; reflecting the fact thatthe GM Camelina oil is a modifiedvegetable oil and therefore contains adifferent chemical e.g. sterolcomposition to fish oil (75).

As formulations for aquafeed diets arenow composed of blended fatty acidsfrom marine and vegetable sources,the Betancor study successfullydemonstrated how LC omega-3Camelina oil is appropriate for use inaquaculture.

9. ConclusionAs discussed above there is a clearneed within aquaculture for analternative, sustainable supply of LComega-3.

The potential of engineered oilseedcrops to meet this demand have beendeveloped by a number of laboratoriesover the last fifteen years, but onlynow, at least with Camelina, has itbeen possible to demonstrate theviability of oilseed crops as a source ofEPA and DHA.

However, it is clear there are anumber of hurdles before a CamelinaLC omega-3 oil can become acommercial reality. It must be hopedthat, subject to the appropriateregulatory and safety approvals, aforward looking aquafeed industrywould be willing to adopt LC omega-3Camelina oil in fish diets, therebyreducing the pressure on oceanicstocks. Camelina engineered toproduce EPA and DHA, when grown insufficient volume could make asignificant contribution to reducing thedemand from capture fisheries (200000 ha of LC omega-3 Camelina couldproduce 150 000 Mt of oil or 15% ofthe global oceanic harvest) (65).

The area required seems large, but itis in fact modest when placed in thecontext of global vegetable oilproduction. For example, such ahypothetical area would be less than3% of the Canadian oilseed sowingarea of a crop like canola (65). Ofcourse before such numbers can beachieved on farms a number of issuesmust be resolved; crucially regulatoryapproval must be sought andobtained, the agronomy and breedingof Camelina must be addressed, oilformulations tested, and the views ofconsumers understood. All of thesesteps require significant effort andresolve, however the demand for LC

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scientificomega-3 is likely to grow, therefore itis our hope that this experimentalterrestrial oilseed source of LC omega-3 can be converted to a commercialreality.

AcknowledgmentsRothamsted Research receives grant-aided support from the Biotechnologyand Biological Sciences researchCouncil of the U.K. Some of the workdescribed was supported by BBSRCgrant BB/J00166X1.

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challenges and possibilities. Aquaculture 436, 95-103.61. Richmond, A. (Ed.), 2008. Handbook ofMicroalgal Culture: Biotechnology and AppliedPhycology. John Wiley and Sons, New York, 584pp.62. Raghukumar, S., 2008. Thraustochytrid marineprotists: Production of PUFAs and other emergingtechnologies. Mar. Biotechnol. 10, 631–640.63. Ward, O.P., Singh, A., 2005. Omega-3/6 fattyacids: Alternative sources of production. ProcessBiochem. 40, 3627–3652.64. Kinney, A.J. 2006. Metabolic engineering inplants for human health and nutrition. Curr. Opin.Biotechnol. 17, 130-138.65. Napier, J.A., Usher, S., Haslam, R.P., Ruiz-Lopez, N, Sayanova, O. 2015. Transgenic plants asa sustainable, terrestrial source of fish oils. Eur. J.Lipid. Sci. Technol. doi 10.1002/ejlt.201400452.66. Qi, B., Fraser, T., Mugford, S., Dobson, G.,Sayanova, O., Butler, J., Napier, J.A., Stobart, A.K.,Lazarus, C.M. 2004. Production of very long chainpolyunsaturated -3 and -6 fatty acids in plants.Nature Biotechnol 22, 739–45.67. Abbadi, A., Domergue, F., Bauer, J., Napier,J.A., Welti, R., Zähringer, U., Cirpus, P., Heinz, E.2004. Biosynthesis of very-long-chainpolyunsaturated fatty acids in transgenic oilseeds:constraints on their accumulation. Plant Cell 16,2734–48.68. Wood, C.C., Petrie, J.R., Shrestha, P., Mansour,M.P., Nichols, P.D., Green, A.G., Singh, S.P. 2009.A leaf-based assay using interchangeable designprinciples to rapidly assemble multisteprecombinant pathways. Plant Biotech J 7(9), 914-924.69. Domergue, F., Abbadi, A., Zahringer, U.,

Moreau, H., Heinz, E. 2005. In vivocharacterization of the first acyl-CoA 6-desaturase from a member of the plant kingdom,the microalga Ostreococcus tauri. Biochem J 389,483–490.70. Ruiz-Lopez, N., Haslam, R.P., Usher, S.L.,Napier, J.A., Sayanova, O. (2013) Reconstitution ofEPA and DHA biosynthesis in Arabidopsis: iterativemetabolic engineering for the synthesis of n-3LCPUFAs in transgenic plants. Metab Eng 17:30-4171. Petrie, J.R., Shrestha, P., Zhou, X.R., Mansour,M.P., Liu, Q., Belide, S., Nichols, P.D., Singh, S.P.(2012) Metabolic engineering plant seeds withfish oil-like levels of DHA. PLOS ONE 7:e49165.72. Ruiz-Lopez, N., Haslam, R.P., Napier, J.A.,Sayanova, O. (2014) Successful high-levelaccumulation of fish oil omega-3 long-chainpolyunsaturated fatty acids in a transgenic oilseedcrop. Plant J 77(2):198-208.73. Vollmann, J., Eynck, C. 2015. Camelina as asustainable crop: contributions of plant breedingand genetic engineering. Biotechnol. J. 10, 525-535.74. Usher, S., Haslam, R.P., Ruiz-Lopez, N.,Sayanova, O., Napier, J.A. 2015. Field trialevaluation of the accumulation of omega-3 longchain polyunsaturated fatty acids in transgenicCamelina sativa: making fish oil substitutes inplants. Met. Eng. Comm. 2, 93-98.75. Betancor, M.B., Sprague, M., Usher, S.,Sayanova, O., Campbell, P.J., Napier, J.A., Tocher,D.R. 2015. A nutritionally-enhanced oil fromtransgenic Camelina sativa effectively replaces fishoil as a source of eicosapentaenoic acid for fish.Scientific Reports Article Number 8104:doi10.1038/srep08104.

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Introduction

Palm oil is obtained from the fruitsof the African oil palm, Elaeisguineensis. Oil palms originated in

western Africa but are now grown intropical regions around the world,most notably in Southeast Asia (seeTable 1).

The fleshy mesocarp of the palmfruits produces a vitamin-rich oil that isa basic foodstuff consumed on a dailybasis by over two billion people (1).Palm oil is a particularly popularfoodstuff in southern and eastern Asiawhere is it used for cooking and as avegetable oil.

Palm fruits are produced in largebunches that hang from the foliagenear the tops of the trees and can beharvested year-round (see Figure 1).

The major acyl components of palmmesocarp oil are oleic and palmiticacids, which makes it especiallysuitable for domestic and commercialcooking or frying applications. The oilis also ideal for the manufacture ofsolid or semi-solid products such asmargarines, creams or chocolate-typeconfectionary items including drinksand spreads (2,3). For this reason,palm oil is used globally as aningredient in numerous processed

foods and confectionary items, such asice cream, biscuits, cakes, chocolate,pizzas as well as in a host of ‘readymeal’ products. Indeed, it has beenestimated that palm oil is present in asmuch as half of all products on sale ina typical supermarket (2).

In addition to the edible oil from thefleshy mesocarp, the seeds, or kernels,of palm fruits contain a different typeof oil that is enriched in medium-chainlauric and myristic fatty acids, whichhave many non-food uses. For

example, palm kernel oil provides thekey functional constituents (i.e. lauricsalts) in many cosmetics and cleaningproducts such as lipsticks, toothpaste,washing-up liquids, shower gels,shampoos, and laundry detergents toname but a few examples (1,2).

Due to the ease with which mediumchain fatty acids are absorbed by thebody, palm kernel oil, which is similarin acyl composition to coconut oil, isalso used in specialised edible applica-tions including some hospital foods,

What is the future for oil palmas a global crop?

Professor Denis J MurphyHead of Genomics and Computational Biology Research Group,

University of South Wales, CF37 4AT, United Kingdom & Chair, Biology Advisory Committee, Malaysian Palm Oil Board,

Bandar Baru Bangi, Selangor, MalaysiaEmail: denis.murphy@southwales.ac.uk

SummaryThe African oil palm, Elaeis guineensis, is the major global vegetable oil crop. Palm oil is consumed daily by over two billionpeople and can be found in about half of all products on sale in a typical supermarket. Increased demand for palm oil,particularly in Asia and Europe, has led to extensive conversion of tropical habitats into plantations. In some parts ofSoutheast Asia, this has had adverse ecological and environmental consequences that have led to calls for boycotts ofproducts containing palm oil. The industry is now responding to these pressures, albeit slowly and belatedly in some cases,and several schemes are in place to provide palm oil that is certified as being of sustainable origin. Advanced breedingmethods, particularly genomics, are beginning to bear fruit in terms of crop improvement for yield, quality, and biologicallybased pest and disease resistance. In the future oil palm is set to become a truly global crop with important new centres ofcultivation being developed in tropical Africa and the Americas.

Key words palm oil, food, detergents, smallholders, plantations, peat soil, sustainability, advanced breeding, genomics, globalisation

AbbreviationsRSPO, Roundtable on Sustainable Palm Oil; HCS, High Carbon Stock; TILLING, TargetIng Local Lesions IN Genomes; CRISPRClustered, Regularly Interspaced, Short Palindromic Repeats; TALENs Transcription Activator-Like Effector Nucleases; QTL,Quantitative Trait Loci

Figure 1. A relatively new commercial oil palm plantation on peatland in centralSarawak, Borneo.

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infant milk formula, and some sportsnutrition products.

Why does palm oil have apoor reputation in somecountries?Despite its evident importance forhuman nutrition, health and hygiene,the oil palm sector has been subject toincreasing vilification in some parts ofthe world over the past decade.

This had been mainly due to theperceived environmental andecological impacts of some of themore recent oil palm plantations,especially in Indonesia, that havesometimes displaced pristine tropicalhabitats (4,5,6). There has also been aperception that palm oil has negativenutritional qualities, despite it being animportant human food product formillennia.

The poor perception of oil palm ishardly surprising because, over recent

years, much of the media coverage ofoil palm has included bleak images ofdisplaced orang utan and other wildlife(7) alongside burning, degradedtropical forests producing hugeamounts of pollution and the release ofgreenhouse gases (8,9).

This perception means that mostpeople in the West have decidedlynegative opinions about oil palm. Incontrast, some groups in Asia havequestioned the motives of certain anti-palm NGOs, which they see asthreatening a key aspect of economicgrowth in the region (10).

The major criticism of the oil palmindustry relates to the expansion ofcultivation that has sometimes (but byno means always) been at the expenseof rainforest.

This expansion has been driven byincreased demand for palm oil both inAsia and Europe. After 2000, increasedglobal demand for food (mainly fromIndia and China) and for biofuels and

other non-food products (mainly fromEurope) were the major factors behindthe conversion of land in SoutheastAsia (mostly in Indonesia) to oil palmcultivation (see Table 2).

In Indonesia the area of oil palmcultivation more than trebled from 2.5Mha (million hectares) to over 8 Mhabetween 2000 and 2014 (11). In somecases this has led to significant habitatloss for iconic species such as orangutan that has triggered large decreasesin local populations (7). There havealso been more general reductions inoverall species biodiversity as complexecosystems are replaced with simplerplantation systems that host fewerspecies (12).

In some quarters, oil palm is nowcharacterised as an evil that needs tobe removed from the landscape. Morerecently there have been several wellpublicised anti-oil palm campaigns,especially in some Western countries.In certain cases these have involved theorganisation of consumer boycotts ofoil palm products ranging fromcosmetics to chocolate (13,14,15).

One example from June 2015, whichinvolved an outspoken attack by theFrench minister of ecology, SégolèneRoyal on a company using palm oil,although this was subsequently fullyretracted, as described in Box 1.

In contrast to these negative views onoil palm, there is an increasingrecognition that oil palm is a necessarycrop that has many benefits, includingsupporting the livelihoods of millionsof small farmers in Asia and Africa (17,18). Rather than boycotting palm oilproducts, therefore, there is amovement to certify that suchproducts are only obtained fromplantations that can verify that their oilhas been produced using sustainablemethods and was not sourced fromareas recently converted from sensitiveforest or peatland habitats.

The most important of these schemesis the Roundtable on Sustainable PalmOil (RSPO) set up in the early 2000s)(19,20).

It is important to realise, therefore,that in contrast to the highly criticalviews on oil palm often heard in theWest, there is another perspective onoil palm that is much less frequentlyheard. This concerns an ancient andbountiful African tree crop whose fruitsprovide a wholesome, vitamin-rich oilthat is an integral part of the diet ofbillions of people in 150 countriesaround the world (1).

It is about a crop that is cultivated bya complex and wide rangingagricultural sector that ranges from

Table 1 Major centres of oil palm productionSource: United States Department of Agriculture, 2012

Table 2 Major palm oil importers* India, Pakistan and Bangladesh;

+ Egypt, Iran, UAE, Turkey, Saudi Arabia, IraqSource: United States Department of Agriculture, 2012

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scientificmillions of smallholder farmers withtiny plots of a few dozen trees to lessthan a dozen very large multinationalplantation companies each growingmillions of trees. While there areundoubtedly examples of poor practicein this vast and diverse industry, seriousefforts are now underway to meetmodern targets for environmentalimpact and overall sustainability.

History of oil palm as acrop The African oil palm has beencultivated as a source of food and fibreby people in Western Africa for manythousands of years and was harvestedby hunter gatherers for many millenniabefore then (21).

Oil palm fruits were highly prized andwere traded across the continent fromthe Atlantic coast to the Red Sea. Forexample, remnants of palm fruits havebeen found in vessels from an EgyptianFirst Dynasty tomb at Abydos dated toat least 5,000 years ago (22).

Until recent times, cultivationremained mainly confined to thecentre of crop origin in the West andCentral African coastal belt betweenGuinea/Liberia and northern Angola.Additional cultivation is now foundfrom 16° North in Senegal to 15°South in Angola, and eastwards toZanzibar and Madagascar, but by farthe best production levels are reachedin the high rainfall areas between 7°North and South from the Equator(23).

In the 19th century, oil palm wasbrought from Africa to Southeast Asiaby Dutch and British colonists. It wasoriginally brought to Java as anornamental plant by the Dutch in1848 but its economic potential wassoon recognised.

Seed selection in the Botanic Gardensof Singapore and Bogor and at the DeliResearch Centre in Sumatra resulted inthe development of commercialvarieties of the crop that have beengrown on an increasingly wide scalesince the 1930s in what are now thenations of Malaysia and Indonesia.Large-scale oil palm cultivation wasfirst commercialised by British plantersin Malaya, during the mid-twentiethcentury. Following the fall in demandfor natural rubber after the 1950s,many rubber plantations wereconverted to oil palm and much of themodern development of the crop hastaken place in Malaysia since itsindependence in 1957 (23).

In 2006, oil palm became the mostimportant source of vegetable oil inthe world (24). Today this former West

African subsistence crop is a majorexport earner for Indonesia andMalaysia (23), which together accountfor 85% of total global production (seeTable 1).

One of the major factors driving thisincreased palm oil production is theseemingly insatiable demand to supplythe expanding populations of Indiaand China (1,24, Table 2).

The 2.4 billion people in these twocountries currently make up about40% of the world population.

In addition to their increasingpopulations, these two nations are

becoming more affluent and theirhigher standards of living areassociated with increasing demands forvegetable oil (see Figure 2).

Oil palm is a uniquelyproductive productThe current average annual yield ofuseful oil from an oil palm plantationin Malaysia is about 3.7 t ha-1 (tonnesper hectare).

However, by improving the way thecrop is managed and harvested, thisyield can be almost doubled to over6-7 t ha-1 on the more advanced

Box 1 – L’affaire Nutella: a minister is shamedOn 15 June 2015, the French ecology minister, Ségolène Royal, metaphoricallygot Nutella on her face (see below) when she made an outspoken attack onthe popular spread because it contains palm oil. As noted in the main text,Nutella only is one of many hundreds of palm-based food products and asmany as half of all supermarket items include some palm oil. The minister wasapparently unaware of this fact as she singled out Nutella during an interviewon the French TV station, Canal+. But she then went further than justcriticising Nutella and advised shoppers to boycott the spread so as to ‘sauverla planète’.

Reaction from the food industry was swift with the minister being roundlycondemned for her misinformed and intemperate attack on Nutella – and byextension a host of other foods. It was pointed out that Ferrero, the owner ofthe Nutella brand, sourced its palm oil from certified members of theRoundtable on Sustainable Palm Oil (RSPO). Just two days later the ministerperformed a volte-face and tweeted her apology thus:

‘L’affaire Nutella’ was amusing in the way it was reported in the Press.However, it also highlights the ignorance and prejudice concerning oil palmthat even affects senior public figures that arguably ought to be betterinformed. In this case, it was very welcome that the minister had the grace toadmit her mistake, but there are many other instances where misinformationhas not been so promptly and publicly corrected.

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commercial plantations (1). Thegreater yield on well-managedplantations is due to such measures asreplanting with the latest geneticallyimproved tree varieties, rigorouslyreducing crop losses from attacks bypests and diseases, optimisingharvesting methods and minimisingspoilage during transport and storage,and using the latest technology inprocessing mills.

Even at current yields, on a perhectare basis, oil palm is 6-10 timesmore efficient at producing oil thancomparable temperate oil crops such asrapeseed, soybean, olive and sunflower(1). In addition to its high oil yield, it isalso a much more efficient crop thanits competitors in terms of the intensityof land management, harvesting andprocessing required.

For example, the annual oilseed cropsrequire replanting each year, whichinvolves regular disruption of the soilstructure by ploughing. This meansthat in oil palm plantations the soilstructure, or rhizosphere, has a richorganic content and is less disruptedcompared to temperate oil crops. Thetemperate oilseed crops also require abrief but intensive annual period ofharvesting and processing that oftenmust be completed in a matter ofdays, whatever the weather. Incontrast, an oil palm tree can becultivated for 20-30 years withoutdisturbing the soil.

Another advantage of oil palm is that,within a given plantation, harvestingand processing can take place on acontinual year-round basis within a

relatively predictable climatic regimethat has far less seasonal fluctuationthan in temperate regions. This meansthat the workforce, machinery, andother assets can be employed on acontinuous basis throughout the year,rather than for a single intensiveperiod, as is the case for annual oilcrops (1).

To draw an analogy with microbialbiotechnology, oil palm husbandryresembles an efficient continuousculture system rather than the muchless efficient batch-processing systemrepresented by annual crop husbandry.

As well as having a competitive edgeover the annual oilseed crops, oil palmis also more productive than other oil-bearing tree crops such as olive orcoconut, which respectively yield oil atabout 2.0 t ha-1 and 0.3 t ha-1.

Given that the annually cultivatedoilseed crops grown in westerncountries only produce oil in the rangeof 0.5-1.5 t ha-1, it is clear that oil palmhas significant potential, not only tosatisfy the increasingly demandingmarkets for edible oil in India andChina, but also to act as a source ofvaluable non-food products for theglobal oleochemicals industry.

In addition, although the use of foodcrops for biodiesel has been rightlycriticised (25-28), if it is reallynecessary to produce biodiesel in theshort term, oil palm is by far the mostefficient and least land-consuming cropthat can be used (28,29). The totalglobal production of palm oil in 2015is estimated at about 72.6 Mt, madeup of 65.2 Mt mesocarp oil and 7.4 Mt

kernel oil (30). As noted below improved breeding

and management have the potentialover the next few years to produce>50% increase in oil yield as aconservative estimate (1). This woulddeliver an extra 35 Mt of edible oilavailable from the same area of landalready in use for the crop, i.e. withoutthe need to expand the area ofcultivation. In contrast, the sameamount of oil from major temperateoilseed crops, such as soybean oroilseed rape, would require cultivationof an additional 30-50 Mha of primefarmland in Europe or the Americas.

This is 2-3 times the entire globalarea already occupied by oil palmplantations and such a vast area ofland is simply unavailable in temperateregions.

Oil palm is grown both bysmallholders and by largeplantation companiesA common misconception about oilpalm is that it is overwhelmingly a ‘bigbusiness’ crop.

In fact, there are more than 3 millionsmallholders growing the crop, nearlyall of whom farm individual family-owned plots. In Indonesia, which is thelargest oil palm producing country,smallholder plots account for 40% ofthe total crop area (31,32). In terms ofinternational trade, the medium tolarge commercial plantations are thedominant players and it is this sectorthat has been most active in joiningRSPO or similar certification schemes.

However, the smallholder sector hasplayed a vital role in the economicadvancement of millions of relativelypoor rural people who have been ableto purchase modern goods andeducate their children (see Figure 3).

Smallholders also have millions ofvotes and are therefore an importantconstituency in rural areas of Malaysiaand Indonesia that governmentsignore at their peril. Unfortunately,most smallholders do not have theresources or economies of scale tomatch larger plantations and theircrops are in general less efficientlymanaged with yields lower than thenational average (33).

Another serious issue for smallholdersthroughout Southeast Asia is that theyare either unaware and/or cannotafford to join sustainability certificationschemes such as RSPO (34).

In general, most smallholders in thepast have not had access to some ofthe best elite germplasm developed bycommercial companies, and in many

Figure 2. Expected trends in world population and edible use of vegetable oil(taken from ref. 19).

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cases they simply buy uncertified seedfrom local merchants. The decision onwhether or not to replant new trees isproblematic for smallholders as itmeans losing their income for as muchas 5 years until the new trees producefruit. It is another 5 years before agood level of productivity is reachedbut these mature trees will thenmaintain good yields for two furtherdecades before a decline sets in.

Many trees on smallholder plots arenow well beyond their productivelifetime and are giving steadilydecreasing yields. National replantingschemes are therefore needed for thesake of the smallholders and theefficiency of the sector as a whole.

The Malaysian government is nowaddressing this problem by committingUS$135 million to facilitate a nationalreplanting programme that isparticularly targeted at smallholders(35). The government has estimatedthat 365,000 ha of mainly smallholderoil palms are 25-37 years old, whichmeans that they are well beyond theirnormal productive lifetime. The aim isto replace 100,000 ha of ageing oilpalms per year by providing grants tosmallholders for the replanting costsplus an annual allowance for the firsttwo years of zero productivity.

It is hoped that the larger commercialplantations will also replant a further100,000 ha yr-1 so that by 2018, over 1Mha will have been replanted. If thiscan be achieved, and with the assump-tion that new oil palms capable of 5-6

t ha-1 will be planted to replace thecurrent ageing stock producing 2-3 tha-1, this rate of replanting could resultin an additional oil yield in the regionof 3 Mt in Malaysia by 2020 (1).

This >10% increase in yield can bereadily achieved without convertingany new land to oil palm and by usingcurrently available plant varieties. Inreality, as discussed below, muchhigher yielding varieties will soon beavailable from ongoing breedingprogrammes, so there is even greaterpotential to increase Malaysia palm oilyields in the coming years. Thereplanting issue that is currently suchan urgent problem in Malaysia will alsoeventually affect Indonesia, which is aneven larger palm oil producer.

Many plantations in Indonesia wereinstalled during a comparatively briefperiod about two decades ago,meaning that most of them will requirereplacement, and consequent loss ofincome for growers, at about the sametime. The situation in Indonesia will beexacerbated by the far largerproportion of oil palm cultivated bysmallholders compared to Malaysia.

It is estimated that over the nextdecade as much as 500,000 ha yr-1 willrequire replanting in Indonesia (1). Itwould therefore be prudent for theIndonesian government to use some ofthe considerable revenues it is nowreceiving from a buoyant palm oilmarket to set aside funds for a large-scale national replanting programme inthe early 2020s.

Such a scheme, which would have aguaranteed bonus in generating higheroil yields, could also reduce futurepressures to convert pristine habitats tooil palm plantations. Failure toimplement oil palm replanting willmean declining yields in the comingdecade and, given the likelihood ofcontinuing international demand forpalm oil, impoverished smallholdersmight decide to embark on a newround of ecologically undesirable landconversion.

Role of Sustainable PalmOil plantationsOver the past year or so the pendulumof informed opinion has started toswing away from a simplistic view ofoil palm as being an unmitigatedenvironmental scourge (see Box 1).

Instead a more nuanced approach isgradually emerging that recognises thegenuine pros and cons of this bountifultropical crop. One of the mostencouraging developments has beenthe establishment of RSPO as a robustand independent body to certify theenvironmental and social credentials ofpalm oil. The RSPO vision is “transformthe markets by making sustainablepalm oil the norm”. As of mid-2015the RSPO had over 2,000 membersglobally that represent 40% of thepalm oil industry, covering all sectorsof the global commodity supply chain.An estimated 11.75 Mt of global palmoil is currently certified by RSPO andthe total is increasing steadily by theyear.

The RSPO scheme is by no meansperfect, as pointed out by some NGOs(36), but more recently the schemehas been praised by other NGOs for itsfirm action in expelling members thatdo not conform to standards (37).

Unfortunately, some companies haveignored the scheme altogether, oftenciting high costs and the difficulties ofmaintaining and checking identitypreservation of RSPO-certified batchesof oil in what has hitherto been acommodity product. The developmentof traceability methods and reliableassays of batch origin are importantchallenges in order to enable qualityassurance of certified oil cargoes.

As we saw above, few smallholderscan afford RSPO certification and thishas led to the establishment of otherschemes with lower thresholds, such asMSPO (38) or ISPO (39) in Malaysiaand Indonesia respectively. While theseschemes have their merits in engagingproducers, especially smallholders, whofeel unable to qualify for RSPO (40),they run the risk of being regarded by

Figure 3. These elderly smallholders farm a 3.2-hectare plot in Sarawak. Theirfarm includes about 500 oil palm trees intercropped with pineapples that providetheir family with the income that has enabled them to educate their children andgrandchildren. The average age of a smallholder in Malaysia is now over 55 butthey still typically play important roles in supporting several younger generationsof the family.

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scientificsome NGOs, palm oil users andconsumers as being a sort of ‘RSPO-lite’ (41).

For this reason, the majority of largeEuropean palm oil importingcompanies, such as Nestle, Unilever,Ferrero, Loders Croklaan, plus manymajor plantation companies, such asSime Darby, IOI and UnitedPlantations, have already signed up toRSPO. The UK government has set anambitious goal of having 100% ofedible palm oil imports as RSPOcertified by the end of 2015.

To quote from a government-commissioned report: “Many major UKand international businesses that use orsell palm oil have made commitments to100% sourcing of sustainable palm oil bya given deadline, generally 2015.” (42).

Similar commitments have beenmade by the governments of Belgiumand the Netherlands (20). Most peoplewould agree that, whatever itslimitations, RSPO probably representsthe best vehicle currently available forthe sustainability of palm oil. This isespecially true for large-scale producersand major users in the food andcosmetics industries, where theirconsumers can be sensitive to theeco-environmental credentials of suchproducts. For example, while onecosmetics retailer (Lush) has boycottedpalm oil (resulting in considerableproblems in sourcing alternatives),another retailer (Body Shop) has used100% RSPO certified palm oil since2011.

Assessing environmentalimpact and sustainability One of the most important limitationsin developing robust policies for asustainable and environmentally soundoil palm industry is a lack of hard factsabout the precise eco-social impacts ofpalm oil production and utilisationfrom ‘cradle to grave’.

As an example, the following quote isfrom a 2015 study on ecosystemservices provided by oil palmplantations:

“Our review highlights numerousresearch gaps. In particular, there aresignificant gaps with respect toinformation functions (socio-culturalfunctions). There is a need for empiricaldata on the importance of spatial andtemporal scales, such as the differencesbetween plantations in differentenvironments, of different sizes, and ofdifferent ages. Finally, more research isneeded on developing managementpractices that can off-set the losses ofecosystem functions.” (43).

Scientific studies of the environmentaland socio-economic impacts of oilpalm are in their infancy and arefraught with problems due to the hugebreadth, complexity, andinterdisciplinary nature of the systemsinvolved. These already formidablechallenges can be exacerbated by theroles of vested interests from all sidesof the debate who will often cherrypick partial data from selected studiesin order to back their alreadyentrenched views. In order to becredible, therefore, studies on oil palmsustainability should be performed byindependent researchers and theresults published in full, preferably inpeer reviewed international scientificjournals. Moreover, such studies shouldnot only focus on oil palm, but shouldcarry out similar assessments of otheroil crops in order to compile acomparative balance sheet of thevarious plus and minus points of othercropping systems, e.g. soybean orrapeseed, in the context of impact andsustainability.

One of the major tools for such aprocess that is much used bypolicymakers is life cycle assessment(LCA). This method seeks to estimatethe impact of all aspects of theproduction process from planting seed,growing, harvesting and processingthe crop (including fuel and labourcosts); application of inputs such aswater, fertiliser, herbicides, pesticidesetc; shipping of the oil overseas and itsdownstream conversion into otherproducts including foods andoleochemicals; transport towholesalers, retailers, and consumers;and finally disposal of all products atthe end of their lifetimes. These areonly a few of the dozens of parametersinvolved in a comprehensive LCA andvery few published studies manage tocover the entire system. Despite thesecaveats and limitations, some usefulLCA data are now emerging where oilpalm is compared with some of theother major oil crops.

An example is a 2015 study, whichshows that overall impact of oil palm,as determined by LCA methods, iscomparable, and sometimes superiorto the temperate crops (44). Manymore such studies are needed in orderto inform better public debate andfuture policy about the trueenvironmental impacts of oil crops.

Ecological and climate-related studiesDuring the past few years there hasbeen a welcome increase in research

on the comparative ecology of oil palmplantations, the impacts of land-usechange, and the possible effects inrelation to climate change, including abalance sheet for greenhouse gasemissions during conversion of forestor peatland to plantations. There isinsufficient space here to discuss all ofthese studies but a few examples willnow be outlined.

The High Carbon Stock (HCS) ScienceStudy was set up by five major oil palmgrowers (Asian Agri, IOI CorporationBerhad, Kuala Lumpur Kepong Berhad,Musim Mas Group, and Sime DarbyPlantation), together with Cargill andUnilever, to increase their commitmentto sustainable palm oil (45). Thisgroup, which is jointly chaired by theacademic, John Raison, and well-known environmentalist, JonathonPorrritt, issued a draft report fordiscussion in 2015, in which theyproduce values for variousenvironmental impacts and list a seriesof recommendations for futureconduct of the industry (46).

Two other recent studies examine thepotential impact of land use andclimate change on biodiversity inBorneo where a great deal of oil palmplanting has occurred (47,48). Theconclusions include the need toestablish nature reserves in uplandareas where climate change will be lesssevere and also to improveconnections between reserves and

Figure 4. Dr Selliah Paramananthananalysing peat soil composition in anoil palm plantation in Borneo. Newanalyses of different types of peat soilsshould inform decisions about whetheror not particular soils are suitable foroil palm cultivation (see main text).

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plantations via wildlife corridors. Oneof the most controversial aspects ofnew palm cultivation is the use oftropical peatland, especially in Borneo.

There are several ongoing studies ofthe impact of peatland conversion interms of greenhouse gas emissions(49-55). However, more studies byindependent groups will be necessaryin order to generate sufficient data fora meta-analysis that could providerobust policy options for theexploitation (or not) of peat soils.

Other studies, including a systematicanalysis of tropical peat soils (56), havedemonstrated an unexpectedlycomplex picture with several different

categories of peat (see Figure 4), someof which can readily support oil palmcrops while other types cannot (seeFigure 5).

The conclusion is that it is notappropriate to impose blanket bans onthe use of peat soils for oil palmcultivation but rather to survey the soilfirst before making a better informeddecision (see Figure 6).

Investing in modern breed-ing and crop managementPlant breeding is a cornerstone of cropimprovement, as shown by the GreenRevolution of the 1960s and 1970s

that successfully averted the spectre offamine in many developing countries(57).

During the 1980s and 1990s,advanced breeding methods, such ashybrid creation, assisted crosses andintrogression of wild germplasm, wereinstrumental in enabling rice yield toincrease five-fold in some regions ofAsia. During the 2000s, muchattention has been focussed ongenomic approaches to plant breedingwith the deployment of a newgeneration of technologies, such asDNA marker-assisted selection,genome sequencing, transgenesis(genetic engineering or GM) andautomatic mutagenesis/selection(TILLING, TargetIng Local Lesions INGenomes) (57).

More recently new genome editingtechnologies such as the CRISPR(Clustered, Regularly Interspaced,Short Palindromic Repeats) and TALENs(Transcription Activator-Like EffectorNucleases) are showing even morepromise for crop and livestockimprovement (58-61). In 2015, theCRISPR/Cas9 system was described in aNature article as “the biggest gamechanger to hit biology since PCR” (62).

All of the above methods haveconsiderable potential for oil palmimprovement and one of the mostencouraging features of recent years isthe development of systems tounderpin future breeding efforts.

A key achievement has been thedevelopment of genomics and related‘omic technologies by oil palmresearchers (1). These effortsculminated in July 2013 when thejournal Nature published twoback-to-back papers that described thesequencing of the genomes of tworelated oil palm species, E. guineensisand E. oleifera plus the associateddiscovery of the Shell gene thatregulates fruit thickness (63,64). Thinshelled fruits, as found in tenerahybrids, are high oil yielding and arenow the basis for all commercial oilpalm production in South-east Asia.Identification of the Shell gene willenable breeders to use molecularmarkers to select suitable breedinglines, instead of waiting three to fouryears or more for the young plants toproduce fruits for selection via a visualphenotype.

This notable achievement wasfollowed in September 2015 by afurther Nature paper reporting theidentification of the epigeneticmechanisms that underlie the serious‘mantling’ problem that has bedevilledefforts to use clonal propagation in the

Figure 5. A deformed oil palm tree growing on waterlogged peatland in Borneo.As noted in ref. 56, there are several types of peatland with different levels oforganic materials. A lower organic content may mean the peat is suitable forpalm cultivation while higher organic contents tend to be unsuitable.

Figure 6. Peatland in Borneo being drained in mid-2015 prior to planting oilpalm. This area is mostly secondary woodland that had been logged over manyyears previously.

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scientificindustry (65). As with some other treecrops, tissue culture andmicropropagation are often the bestway to produce thousands or evenmillions of clonal copies of selectedelite individuals. Unfortunately, in thecase of oil palm, epigeneticabnormalities regularly arise duringtissue culture but it can take severalyears before the resultant deformed or‘mantled’ fruits can be observed.

This has cost the industry millions ofdollars and much wasted time ingrowing useless trees. The elucidationof the ‘mantled’ trait will allow formuch earlier detection and eliminationof affected trees and will thereforecontribute to raising overall oil yield inthe industry (66).

Oil palm breeders are also usingadvanced selection methods, includinggenetic markers based on DNAsequences, to assist in the selection offavourable agronomic traits. Othermodern techniques like associationgenetics and quantitative trait loci(QTL) analysis are also enablingchromosomal regions and individualgenes involved in the regulation ofimportant traits to be mapped andidentified (57). These methods haverecently been used to map the lipasegene involved in oil deterioration inripe palm fruits (67) and QTL analysisof genes regulating the fatty acidcomposition of palm oil (68).

Bioinformatic and ‘omics methods arebeing used to annotate the oil palmgenome and to discover genes

involved in the regulation of key traitssuch as oil yield and quality, semi-dwarf trees and pest/disease resistance(69-72) (see Figures 7 & 8).

Efforts are also underway to breedhigh-oleic varieties of oil palm. Thesevarieties could compete with oilseeds,such as sunflower and rapeseed, both

for premium edible markets and asfeedstocks for medium-valueoleochemicals such as lubricating oils(1).

The future of oil palm inSoutheast AsiaAlthough, it should be possible toproduce a lot more palm oil byincreasing the crop yield, it seemsinevitable that, at least in the short-term, some additional land conversionwill be necessary (1).

There are several drivers for thecontinued expansion of demand forpalm oil in the medium to long-termfuture, the most important of whichpopulation growth and economicprogress in many developing countries.In 2015, a global area of about 16Mha produced 72.6 Mt of palmmesocarp + kernel oils. Forecastingfuture levels of demand for anycommodity is always challenging, butthe following estimates from severalreliable sources predict that about 77Mt palm oil will be required by 2018(73); 84 Mt by 2020 (74); andbetween 93 and 156 Mt by 2050 (19).

This is a formidable challenge butone that is achievable by a judiciousmixture of managementimprovements, replanting bettergenetic stock, and some expansion ofcultivation into other parts of thetropics. Providing any new cultivationis carried out in an environmentallyresponsible manner, there are benefitsfrom diversifying oil palm cultivationinto other regions of the world. Forexample, a more dispersed croppingarea will be more resilient to threatsfrom climatic factors or locally adaptedpests and pathogens. In this respect,the current concentration of >85% ofglobal palm cultivation in onegeographical area Malaysia/Indonesia)is far from ideal.

The expansion of cultivation intosuitable areas of West Africa andSouth/Central America that is nowunderway will create a more secureproduction system in the longer term.It is also worth pointing out that, asshown in Figure 9, none of theseregions comes close matching to thecropping intensities already adopted inlarge parts of the USA and Europe.

Some of these measures could have asignificant impact on output within thenext five years. For example, if theplanned replanting programme inMalaysia (see above) is carried out, itcould deliver an additional annual yieldof 5 Mt palm oil on existing land. Ifsome of the best existing experimental

Figure 7. Mature oil palm trees canreach over 20 metres in height, whichmakes it difficult and costly to harvestthe fruits. Semi dwarf trees use lessenergy in making a tall trunk and canproduce higher fruit yields. They arealso much easier to harvestmechanically.

Figure 8. The most important pathogen of oil palm is the fungus, Ganodermaboninense, which forms fruiting bodies around the base of infected trees andeventually kills them. Genomic methods are now being developed to combat thisdisease, which affects 30-50% of oil palms in some parts of Indonesia and

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breeding material, theoreticallyyielding 8-10 t ha-1, could bedeveloped for commercial plantingthroughout the sector then yield couldbe increased by 50% or more. Thiscould deliver as much as 30 Mt moreoil per year – again without requiringfurther land conversion.

Further into the future, there is theprospect of additional yield gains byusing modern breeding technologiesto produce fruits with a higher oilcontent and dwarf oil palms that bearmore fruit and are easier to harvestmechanically. At present, we cannotquantify the benefits of such biologicalinnovations but they could potentiallydeliver tens of millions of tonnes ofadditional oil.

The future of oil palm inAfrica and the AmericasIn recent years there has beensignificant expansion of oil palmcultivation in Africa and the Americas.

Currently, the three major centres ofcultivation in Central/South Americaare Colombia, Ecuador and Honduraswith a modest annual output of 2 Mtoil. According to IIASA estimates, thesethree countries and Peru have somepotential to expand cultivation but byfar the largest new prospective area isin Brazil. Oil palm is more suitable as acrop in low elevation regions in thehumid tropics and can even toleratethe highly acidic non-forest soils ofAmazonia (75). In Brazil, an estimated32 Mha (excluding rainforest) aresuitable for oil palm production (76),which is double the entire global oilpalm area at present. It should bestressed that the vast majority of this

possible expansion into oil palm inSouth America would be on grasslandor planted pasture with very little, ifany, forest conversion (77).

Conversion of such land wouldtherefore have a lower impact onbiodiversity and other sensitiveenvironmental indicators that theconversion of tropical forest.

West Africa is the historical home ofthe commercial oil palm and, prior tothe 1960s, Nigeria was a globallydominant producer. Since then, civilconflict plus poor investment andmanagement of the largely smallholderdominated industry led to a sharpdecline in palm oil production.

By 2000, Nigeria was unable even tomeet local demand and the country isnow a net importer of edible oils (78).

However, the buoyant internationaldemand for palm oil is stimulating thereplanting of disused plantations orestablishment of new plantations inseveral parts of West and Central Africa(79).

Much of this expansion will berequired just to meet localrequirements for vegetable oil. Forexample, in 2010, Africa imported 2.4Mt palm oil, mostly from Malaysia. It isestimated that 24 Mha is suitable forgrowing oil palm in Nigeria alone (80).In terms of climate and agronomy,another promising region for new oilpalm cultivation in Africa is in theCongo River basin (81) and plantationcompanies are also steadily acquiringland in this and other parts of Africa(82).

ConclusionsThe oil palm industry faces many

challenges in the future. However, the tools to surmount these

challenges already exist and have thepotential to further transform thishistoric crop into a truly global sourceof nutritious food and valuable non-food products for the growing worldpopulation. Higher yielding cultivarswith improved oil compositions andgreater resistance to pests and diseaseswill be available.

We can also look forward to anextension of oil palm cultivation in newareas of the tropics. Over the nextdecade, West and Central Africa willbegin to emerge alongside Central/South America as major producers ofpalm oil, initially for local consumptionbut eventually for export to globalmarkets. Between them, West/CentralAfrica and Central/South America havethe capacity to convert well over 30-40Mha to oil palm with a current yieldpotential of 130- 170 Mt oil, andmuch more than that if the expectedincreases in crop yields are realised.

It is highly unlikely that such a vastarea, which is more than double thepresent oil palm area, will need to beconverted. However, even if only aquarter of this land is changed to oilpalm plantations, these regions couldbe producing as much as 50-60 Mt oilby 2025. This is close to the presentglobal total and demonstrates that adoubling of palm oil production in thenext few decades is quite feasible.

A redesign of plant architecture,especially the breeding of shorter stem,can further increase yields as well astransforming the management andprocessing of the crop. If these andother genetic improvements and

Figure 9. Proportion of cropland around the world. Note that by far the most intensively cropped areas are found in

Europe, North America, and the Indian Subcontinent. In contrast, Southeast Asia has more moderate crop levels (84).

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scientificmanagement efficiencies can beachieved, the resulting increased palmoil output could more than meet eventhe highest projections for futurevegetable oil requirements. Moreover,given its superior yield and land-useefficiency, oil palm might eventuallydisplace some of the less efficienttemperate oilseed crops as thepreferred source of oil for many edibleand non-edible markets.

Policy ProposalsThe oil palm industry faces manychallenges regarding its environmentalcredentials.

These challenges are common to allregions and companies with littledifferentiation among the generalpublic between ‘good’ and ‘bad’sources of palm oil.

Therefore the entire sector tends to be stigmatised by poor practice in afew areas.

It is highly desirable that this hugeglobal industry, which is worth overUS$50 billion annually, shouldcollectively redouble its efforts toaddress sustainability and public imageissues as a matter of priority. One wayto meet such challenges would be toform a global industry-wide body tofacilitate best practice.

The remit of such a body couldinclude: � Sponsoring independent researchacross the various disciplines related tothe sector. Specific R&D areas mightinclude yield and oil quality, pest/disease resistance, addressingmanagement-related issues such asecological and environmental impact,product image, tree replanting, laboursupply and mechanisation. � Engaging independent experts inorder to improve communications withNGOs and engage more effectively ina constructive dialogue with thegeneral public. � Development of robust methods tovalidate sustainably certified palm oil.As certified palm oil (e.g. via RSPO)becomes increasingly common it willbe necessary to validate theprovenance of such oil in order toreassure end users, includinghousehold consumers. Thedevelopment of reliable traceabilityprotocols and verification methodsfor batch origin (as already done forolive oil) are important challenges inorder to enable quality assurance ofcertified palm oil cargoes.

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References are not essential, althoughthey should be used to justifystatements where appropriate.

Layout and typinginstructionsSI units and the English language mustbe used, the spelling being generallythat of the Concise Oxford Dictionary,9th Ed, so that words such as fertilisershould use ‘ise’ rather than theAmerican ‘ize’ spelling.

Times New Roman 12 point fontshould be justified for normal text andArial should be used for headings.Standard abbreviations (e.g. Fig. andFigs) are acceptable, but specialistabbreviations and terms should bedefined in a short Glossary,immediately beneath the Summary.

Additionally, keywords should also beincluded beneath the summary.

Full stops are not used in commonlyaccepted abbreviations (e.g. USA, UK)and should not be used when anabbreviated word ends with the sameletter as the complete word (e.g.,Florida as FA and cultivar as cv.).

Latin terms such as circa should beitalicized, for which ca is the abbrevia-tion.

Commercial chemicals should bereferred to by their approved commonnames, but where a proprietary nameis relevant and unavoidable it shouldbe used with a capital initial and themanufacturer named at the firstmention.

Billion may be expressed as thousand

million (eg a billion hectares as 1 000Mha) although the SI expression Gha isacceptable.

Concentrations and rates ofapplication should be clearly expressedand unambiguous, using, for example,mg/litre, or mg/L, mg/kg (not ppm).

Dates should be expressed as day,month, year, as for example, 18th May2010.

Currency references should use thestandard international abbreviations,although US$, € and £ are acceptablefor US dollars, Euro and GB £respectively.

Wherever possible financial detailsshould be quoted in one of thesecurrencies, although where this is notpossible a standard list of abbreviationsis available at <http://www.forex-rates.biz/currency-abbreviations.htm>which was accessed in March 2011.

The full Latin name of an organismshould be given at the first mention,e.g. Heterodera avenae; an abbreviatedname of the organism may be used forsubsequent mentions, e.g. H. avenae.Names should follow the appropriateinternational codes.

Naturally occurring infraspecificvariants should be described asvarieties, as for example Medicagopolymorpha var hispida and where usedrepeatedly in the text variety may beabbreviated to var. or vars.

The word cultivar should be restrictedto forms in cultivation and which needto be propagated either by seed orvegetatively and can be abbreviated tocv. or cvs after first use in the text.

They will normally have specificadvantages and distinctive featureswhich will enable them to bedescribed and differentiated fromothers.

Named cultivar should be in normal,ie not italicised font as for exampleTaxus baccata ‘Variegata’ or Taxusbaccata cv Variegata.

Always use numerals for specific unitsof measurement (e.g. 14 m, 2 d, 3wk). For other quantities up to andincluding nine, spell out in full (e.g.four plots, two experiments, ninelarvae). Use numerals in all instancesfor ten or over (e.g. 20 fields).

Large numbers should be separatedby spaces every 000, rather than byuse of a comma, e.g., 10 000.

Hyphens should be avoided ifpossible, for example use ‘cooperate’rather than co-operate’.

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instructions

World Agriculture problems and potentialInstructions to contributors

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instructionsWhere authors need to reproduce

information protected by copyrightthey must obtain permission toreproduce the item before the article ispublished in World Agriculture.

Sequence of headingsEach paper should commence with ashort concise, accurate and informativeSummary, normally of approximately250 words, that includes the issuesposed, the subject covered and theconclusions drawn.

The Introduction should set out thebackground to the subject. This is tobe followed by the main body of thearticle in sections each of which isheaded by terms defined by the natureof the paper, for example:Background, Review of evidence, thePresent situation, Problems to beconfronted and Resolution.

The paper should conclude with aDiscussion and/or Conclusions sectionand finally References. Layout ofheadings should follow the guidancebelow:Title, bold 16 pointAuthor name AffiliationMain headings central bold Arial 14point fontSecondary headings: left justified,bold Arial 12 point font Tertiary level: left justified, Arial 12point font Quaternary (if necessary) left justified,Arial 12 point italics

Tables, figures, linedrawings, photographsand graphsFigures, Tables and Photographsshould be placed in a separate set offiles from the text (indicate in textdesired location, e.g. with the phraseTable xx near here on a separate line insquare brackets if possible).

Each should be numberedsequentially with the title in TimesNew Roman 12 point font beneath.

All figures and tables should be ofhigh resolution. If possible figures andtables should be submitted in Excel(same table(s) could be in Word, inaddition) and also if possible submitthe data from which the figure hasbeen produced. Make sure all thedenominations are according tointernational standards and thelegends are clear.

Tables with suitable titles must benumbered using Arabic numerals insequence and be understandablewithout reference to the text. Use a

horizontal line to separate columnheadings from data and at the bottomof the table; avoid column lines.Excessive numbers of columns shouldbe avoided.

Illustrations in the form of textfigures, line drawings, and computergenerated figures and graphs withtheir captions should all becomprehensible without reference tothe text.

All photographs should be half toneor colour, have a high definition (>5million pixels/photo) and the softwareshould be IBM/DOS compatible. Eachphotograph should be adequatelyidentified with the author, paper andplate number.

Photographs submitted electronicallymust be in separate jpg files with theessential information included in theproperties box for the file.Alternatively, photographs may beposted to the Editor on disk (requestaddress by e-mail). The plate number,authors and an indication of the papertitle should also be given in a separateelectronic file. Electronic-mail issatisfactory for correspondence, textand tables.

Standard deviations, standard errorsof the means and “n”, the number ofobservations associated with eachmean, should all be presented.

References and citationsAll references in the text should begiven as numbers, although theauthor(s) name may be givenimmediately before the number, ifhelpful.

References should be numberedsequentially using superscript, in theorder in which they appear the first as

1; all subsequent references to thesame paper using the same number.Where more than one paper is cited,the numbers should be listed innumerical order separated by acomma.

In the Reference Section papersshould be listed in numerical order inthe format:

1. Anon (yyyy) Web page title.<http://www.organisation/page/file_or_other_address> accessed dd mmmyyyy.

2. Klass, D W (ed.) (1979) Currentpractice of clinicalelectroencephalography. New York,Raven Press, 1979 ISBN n nn nnn nnnnnn.

3. Organisation (yyyy) Web pagetitle.<http://www.organisation/page/file_or_other_address> accessed ddmmm yyyy.

4. Regan, D & Smith, A (1979)

Electrical responses evoked from thehuman brain. Scientific American, 241,134-52.

5. Smil, V (2011) Nitrogen cycle andworld food production. WorldAgriculture, 2 (1) 9-13.

6. Blogs, P (2010) Personalcommunication.

7. Baggins, B (1991) Title of paper.In: Proceedings of--- (ed., R.E. Blogs),Name of sponsor or organiser, USA, 6-8 June 1991, pp.91-4

When a reference includes an issuenumber, include the volume number inbold and the issue number in brackets,between the volume and the first andlast page numbers.

Communications with theEditor for publicationComments & Opinion and Letters tothe Editor by e-mail will also beconsidered for publication.

These should be concise andsubmitted for the purpose of makingobjective comments on publishedarticles, or on important subjects thathave not been covered.

Submission, Editing andAcceptanceManuscripts should be formatted to A4justified using MS Word and 12 ptTimes New Roman font.

Authors’ names, qualifications,honours and affiliations should beincluded and submission will assumethat the author accepts the conditionslaid down in these Instructions to

Contributors and that copyright isheld by World Agriculture: problemsand potential. Manuscripts should besubmitted to the Editor by electronicmail, with the address of:editor@world-agriculture.net

Articles that are accepted by theeditorial board will be edited and theEditor reserves the right to modifystatements made by the author, or toask for a revision, although the editedversions will be sent to the author forhis or her agreement beforepublication.

The author’s response must occurwithin 96 h. Moreover, during therevision process it is essential thatauthors respond quickly and reliably torequests for amendments, otherwisethe publication deadline will beforfeited.

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