Role of Metabolic Phenotyping in Understanding Obesity and Related Conditions in Gulf Co-operation Council Countries.

Muhammad S. Ahmada, Hutan Ashrafianb, Munirah Alsalehb, Elaine Holmesb.

aDrug Metabolism Unit, King Fahad Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia. bSection of Biomolecular Medicine, Division of Computational and Systems Medicine, Department of Surgery and Cancer, Imperial College London, SW7 2AZ

Keywords:

Obesity, Gulf Cooperation council (GCC) countries, Metabolic Profiling, Diabetes.

Running title:

Role of Phenotyping in Understanding Obesity in GCC Countries.

Acknowledgements:

This project was funded by the Deanship of Scientific Research (DSR), King Abdulaziz University, under grant No. (2-141-35-HiCi). The authors, therefore, acknowledge with thanks DSR technical and financial support. MA is supported by the Imperial College Stratified Medicine Graduate Training Programme in Systems Medicine and Spectroscopic Profiling (STRATiGRAD) and King Abdullah Foreign Scholarship Programme, Ministry of Education.

Address of corresponding author and e-mail address:

Elaine Holmes: Division of Surgery and Cancer, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, U.K. email: elaine.holmes@imperial.ac.uk

Potential conflicts of interest:

All authors declare that there is no conflict of interest.

1

Abstract:

Obesity is a major health concern in the Middle East and the incidence is rising in all sectors of the

population. Efforts to control obesity through diet and lifestyle interventions and by surgical means

have had limited effect and the gene-environment interactions underpinning the development of

obesity and related pathologies such as metabolic syndrome, cardiovascular disease and certain

cancers are poorly defined. Lifestlye, genetics, inflammation and the interaction between the

intestinal bacteria and host metabolism have all been implicated in creating an obesogenic

environment. We summarize the role of metabolic and microbial phenotyping in understanding the

etiopathogenesis of obesity and in characterizing the metabolic responses to surgical and non-

surgical interventions intervention and explore the potential for clinical translation of this approach.

Abbreviations:

BMI Body Mass IndexBP Blood PressureGCC Gulf Cooperation CouncilTLR Toll Like ReceptorGF Germ-FreeUAE United Arab EmiratesSHIS The Saudi Health Information SurveyCVD Cardiovascular DiseasePIH Pregnancy Induced HypertensionRCT Randomised Controlled TrialNCDs Non-Communicable DiseasesWHO World Health OrganisationIFSO International Federation for the Surgery of Obesity and Metabolic DisordersNMR Nuclear Magnetic Resonance SpectroscopyMS Mass SpectrometryMWAS Metabolome Wide Association StudyBCAA Branched Chain Amino AcidsPPARs Peroxisome Proliferator-Activated ReceptorsSIFT-MS Selective Ion Flow Tube Mass SpectrometryNAFLD Non-Alcoholic Fatty Liver DiseaseRYGB Roux-En-Y Gastric BypassGABA Gamma-Aminoisobutyrate

The obesity epidemic

Globally obesity is rising at an alarming rate in both developed and developing countries. Obesity

and its co-morbidities including cardiovascular disease, diabetes and certain cancers have become a

severe health and socioeconomic problem and are starting to appear earlier in life. The McKinsey &

Company global report on obesity in 2014 identified obesity as one of the top three man-made

2

social burdens, approximately equal to smoking and armed violence accounting for five per cent of

all global deaths 1. Understanding the contribution of gene-environment interactions in the aetiology

and development of obesity, particularly the contribution of nutritional and gut microbial factors as

drivers for adverse or protective effects, is of prime importance if we are to reduce the global

burden of disease in both western and developing world populations. Recently discovered genetic

determinants of body weight and obesity, most notably common variants in the FTO and MC4R

genes 2, explain only a small proportion of body mass index (BMI) population variance and constitute

a 3 fold obesity risk in children but only 1.8 fold increased risk in adults. Thus, environmental factors

are overwhelmingly important in explaining the trends and differences in levels of risk factors and

obesity-related disease rates across populations. Development of obesity reflects the balance

between food and energy intake, metabolism, gut microbial contributions and physical activity.

Obesity and its co-morbidities are largely preventable given the close association with overnutrition

and weight. The impact of diet on health and disease at the individual and population level has

become an urgent research imperative and area of public health concern. From population studies,

it can be concluded that obesity accounts for two thirds of individuals affected with hypertension 3, 4.

Obesity clusters with raised blood pressure, fasting plasma glucose, hypertriglyceridemia, and low

high-density lipoprotein (HDL) levels to constitute the metabolic syndrome. The underlying

mechanisms connecting these remain poorly understood whilst additionally the prominent

association between obesity and cancer elevate the public health concerns of obesogenesis.

Intensive research efforts are urgently needed to identify further environmental influences on BMI

levels to better inform preventive efforts and public health policy.

In parallel with large cohort studies, with their legacy of biobanks of samples across a range of

populations, an array of post-genomic technologies (transcriptomics, proteomics, metabonomics

etc) have been applied to characterizing obesity and diabetes in large population studies, in order to

improve our understanding of the aetiology of obesogenesis and to discover new means of

therapeutic management. Of the ‘omics’ technologies, metabonomics provides the most accessible

window on investigating the impact of nutritional and extragenomic factors on obesity and diabetes

since metabolic profiles of easily obtainable biofluids such as blood plasma and urine carry

information relating both to genetic and environmental influences 5. Recent research into the role of

the gut microbiota in influencing weight loss or weight gain also raises the idea that metagenomics,

or sequencing of the intestinal or faecal microbiota, may deliver clues on the changing landscape of

obesity 6. We explore the potential of these technologies in unravelling metabolic and environmental

contributors to obesity in the Gulf Cooperation Council (GCC) countries.

3

Etiological Drivers of Obesity

Many factors contribute to the global rise in obesity including a shift towards a more sedentary

lifestyle and associated behavioural changes such as number of hours spent on computer-related

activities in childhood, increased availability of fast foods with high fat, salt and sugar composition,

increase in portion size and general reduction in dietary fibre. Evidence for the role of inflammation

(including IL-6, TNF-α and other inflammatory cytokines and their triggers such as toll like receptors),

endocrine disruption, antibiotic intake and the gut microbiota either in the aetiology and

development of obesity, or as factors to be considered in calculating obesity-related disease risk, are

also currently under scrutiny 7. Although poor diet and overnutrition account for the majority of the

obesity epidemic, the role of inflammation and the gut microbiota are inextricably intertwined. Co-

evolution has influenced the microbiome of organisms such that metabolic complementarity exists

within the microbiota and that critical biosynthetic pathways are provided for the host that

significantly extend host metabolic capacity. In addition to their primary function in host immunity

the microbiota are known to be associated with harvesting of energy, metabolism of xenobiotics and

have been implicated in metabolic signaling. Landmark studies in both animal models and humans,

such as those from Gordon’s group, have shown that obese and lean individuals carry a different gut

microbial composition 8, 9. These studies showed that microbiota in ob/ob mice were more effective

at releasing calories from food during digestion than the +/+ microbiota and that this trait is

transmissible, since colonization of germ-free mice with an ‘obese microbiota’ induced a significantly

greater increase in total body fat than colonization with the equivalent ‘lean microbiota’. Similarly,

Germ-free (GF) mice are protected against the obesity that develops in conventional mice after

consuming a Western-style, high-fat, sugar-rich diet 10. Sequencing data from the highly variable 16S

region of ribosomal RNA genes including shotgun metagenomics from stool samples can be used to

characterize the abundance of different taxonomic groups of bacteria present in the obese state

(such as the relative composition of Firmicutes and Bacteroidetes) 9 whilst also probing mechanistic

aspects of the relationship between the microbiome and human host 11. Supporting these

observations, clear differences in microbially-derived metabolites have been shown in urinary, fecal

and plasma profiles from obese individuals with metabolites such as hippurate (glycine conjugate of

benzoic acid) and phenylacetylglutamine (hepatic conjugation of glutamine with phenylacetlic acid

derived from microbial conversion of phenylalanine) being associated with leaner phenotypes in a

range of animal models and in man 12, 13.

Given the scale of the obesity pandemic and the universal pervasiveness of the fast food industry, it

is unlikely that a single point of attack will be successful in combating obesity. Barker’s hypothesis of

4

the thrifty phenotype 14, building on the thrifty gene 15, proposes that the human body is set up to

conserve energy at multiple levels: fat storage, hormonal regulation of appetite, evolving in response

to centuries of food insecurity would suggest that the human body is predisposed to weight gain

when shortage of food is not an issue.

The percentage of low birth-weight babies in the Middle East is on average 15% compared to a 7%

rate in Central and Eastern Europe 16. Given the known interaction between the microbiome in the

preterm and low birth-weight infant and the adverse impact of low birth-weight on the prevalence

for development of metabolic syndrome and other obesity-related conditions, the greater tendency

for low birth-weight infants in the GCC states may contribute to the overall obesogenic and diabetic

landscape.

Obesity background and clinical challenges of obesity in GCC countries

Obesity is one of the major public health problems in the six Arabian GCC countries (Saudi Arabia,

Oman, Bahrain, United Arab Emirates(UAE), Qatar, and Kuwait)17. Internationally, GCC countries are

among the richest and most urbanized, and since 1970’s they have experienced 400% increase in

urbanisation and rapid economic growth 18. The population within the GCC has been subject to an

immense socio-economic upheaval over the past century that has led to a commensurate shift in

community lifestyle and healthcare. For example, the population status in the UAE was transformed

from a developing nation where fishing was the predominant industry to one of a developed country

with a highly ranked global hydrocarbon oil and gas economy 19 that carries an increasing impact on

the global finance sector. There have been significant reductions in physical activity, sport and

regular exercise that have been associated with cheaper and easier access to travel and migrant

working support to carry out many daily life activities 20. These environmental effects are further

compounded by the adoption of traditionally ‘Western’ diets that are typically high in refined sugars

and fat and low in fibre, fresh fruit and vegetables. For example the consumption of meat in Saudi

Arabia has increased by 500% over a two-decade period whilst the consumption of cereal conversely

has significantly decreased 21 22. The compound effect of both lifestyle and poor diet is also a known

driver of obesity-associated diseases (such as diabetes and metabolic syndrome) in many nation-

states. However, in the context of GCC countries, it has additionally unmasked this population’s

previously unrealized higher genetic propensity for these conditions. For example, when individuals

of Middle Eastern descent living in Sweden were compared to the native national population they

were found to be two-to-three times more susceptible to diabetes 23.

5

Saudi Arabia’s national health survey in 2005 showed that 66.3% of males are overweight or obese,

compared to 71.4% of females between 15-64 years old 24. A more recent survey in 2013 involving

10,735 participants 25 showed slightly better health statistics corresponding to a reduction in obesity

of 4.4% for men and 10.7% for women. This reduction may be associated with Public Health

programmes delivered by the Saudi Ministry of Health to combat obesity. The 2013 survey reported

a higher rate of obesity amongst women: 33.5% of women with a BMI ≥30 kg/m2 as opposed to

24.1% men. Being married and hypertension were associated with obesity in both men and women,

and for men additional factors included poor diet, diabetes, lack of physical exercise and

hypercholesterolaemia. The highest overweight and obesity rates in the Gulf region were reported in

Kuwait and Qatar, 77.7% among females and 73.6% in males, and 78.3% females and 68.9% males

respectively 26. Nearly half of women in the gulf region are obese with the highest percentage, 47.9%

is in Kuwait, followed by Qatar, 45.3% and Saudi Arabia 33.5% 22, 26. Multiple pregnancies, low

physical activity and lifestyle/cultural restrictions are major contributors to obesity in women 21. Low

levels of physical activity were prevalent in men and women, with 75.1% of women stating that they

practiced negligible levels of physical activity.

Obesity associated comorbidities are reaching an alarming rate in the Gulf area. Type 2 diabetes

accounts for 90% of total diabetes cases 27. Three out of the world’s top ten countries with the

highest diabetes prevalence are from the GCC region as shown in Table 1. Saudi Arabia is in 7 th place

with 24% diabetes prevalence, and by 2035, an expected 0.5% increase will make the country the 6 th

highest worldwide. Kuwait came in at 9th place with 23.1% diabetes prevalence, followed by 22.9% in

Qatar 28. Similarly to diabetes, 37.7% of Saudi adults are diagnosed with hypertension and the figure

increases to 40% among United Arab Emirates nationals 26. Nearly one-third or more of Gulf adults

are diagnosed with metabolic syndrome, 20.7–37.2% in men and, 32.1–42.7% in women, which is

substantially higher than the rate in most developed countries 29. High BMI is also associated with

complications during pregnancy such as pregnancy induced hypertension (PIH) and gestational

diabetes. In Qatar, which is reported to have high levels of PIH compared to global and regional

profiles, women of Qatari nationality were 30% more likely to have PIH 30 with the odds ratio

increasing 10 fold when BMI >30.

Nearly 50-60% of the gulf countries inhabitants are younger than 20 years old, which makes battling

childhood obesity a critical health challenge 26. Obese children are likely to carry on the excess

weight into adulthood and develop obesity-related diseases at a younger age 31. Obesity in the Gulf

region appears to develop at a young age as shown in a review on the prevalence of overweight

among preschool children (0-5 years) in 94 countries. Gulf and other Arab countries showed a high

6

prevalence of overweight, ranging from 3.1% to 9%, which is higher than the global rate, 3.3% 32.

Obesity and overweight continue to increase with age. A Saudi Arabian national survey for children

and adolescents (5 to 18 years) showed that the overall prevalence of overweight, obesity and

severe obesity was 23.1%, 9.3% and 2%, respectively 33. A recent study by Boodai et al indicated that

many Kuwaiti adolescents (mean age 12.3 years) already had significant cardiometabolic risk factors,

such as high levels of liver enzymes, C-reactive protein and insulin resistance 34. In a cohort of

adolescent (12-19) Saudi girls, the strongest dietary factors directly associated with obesity were

intake of sweets and consumption of fast food meals more than three times a week 35.

The consequences of this socio-economic shift have introduced a state of increased obesity through

the paradigm of ‘diseases of affluence’. For the GCC states, this has (i) resulted in the development

of prevailing lifestyle trends towards predominantly obesogenic environments (ii) led to an increased

availability of hyper-caloric and obesogenic products, (iii) unmasked several underlying obesity-

associated disease susceptibilities and (iv) has defined novel requirements in health policy and

strategy. One of the biggest challenges in some countries is accurate recording of weight or

diagnosis of obesity. From an in-patient study of 155 participants in the UAE, 66% met the criteria

for obesity and a further 32% for overweight, yet of these patients, only 9% had BMI or obesity

recorded in their patient records and even fewer (6%) were referred to a dietician, highlighting a

significant gap in obesity management 36.

The multi-factorial challenge of obesity and its myriad of associated conditions ranging from the

metabolic syndrome, type 2 diabetes mellitus, cardiovascular disease, sleep apnea, cancer, and

infertility presents a substantial burden on national health resources and economics through lost

work, decreased employment and increased healthcare costs 37. Although at a superficial level, the

World Development Indicators suggest a comparatively low per-capita healthcare expenditure in the

GCC countries, the actual healthcare expenditure on obesity in these nations is to some degree

concealed by several factors. For example, the calculations of these indices do not always

differentiate population spend on nationals and migrants; the latter of which may be substantially

greater in volume. Other aspects include future healthcare costs of younger patients who, despite

becoming obese, are yet to suffer from complications of their disease do not yet figure on balance

sheets and health tourism whereby individuals are treated abroad for their obesity-related

conditions, making the economics difficult to forecast.

Addressing these lifestyle trends and the adoption of novel preventative strategies will therefore

require a strengthening of national policy in anti-obesity healthcare education. Specialist obesity

units and the establishment of centrally regulated multi-disciplinary anti-obesity teams can in turn

7

be introduced to minimize obesity and its co-morbidities in line with national and international

targets. These may be achieved through the next generation of cutting-edge preventative, diagnostic

and treatment strategies including both pharmacotherapy and bariatric-metabolic procedures.

Current strategies in GCC countries for addressing the clinical and economic burden of obesity

The Gulf countries have a strong role in contributing to obesity research and a recent study

concluded that the quantity and quality of obesity-related research was high, with a total of 1,121

documents, amounting to 1% of the global output 38. This underscores the serious response across

these nations to tackle the obesity problem. Methods for combating the high levels of obesity in the

Gulf States have varied from country to country and have tackled the problem in a multimodal

manner.

Public health initiatives: Gulf cooperation council countries have adopted several individual

measures with limited success to address the obesity epidemic in the region. Several public

conferences have been hosted amongst the Arab nations to address the societal issues of obesity

and diabetes. The third Arab Conference on Obesity and Physical Activity was held in Bahrain in

January 2010 39, which amongst other recommendations, built on Bahrain’s success in weight

reduction by implementation of a series of nutrition clinics. Bahrain was listed as fourth in the world

for male obesity in the 2015 version of the Economist’s Pocket World but the government driven

nutrition clinics have had a measurable effect with three quarters of those signing up achieving

weight loss. Similarly, Kuwait has responded to the obesity crisis by implementing the Kuwait

National Programme for Healthy Living in 2013 40.

Examples of national initiatives include a “national campaign against overweight and obesity”

adopted by Saudi Arabia with the aim of encouraging physical activity and healthy eating and have

supplemented this by recognising obesity and diabetes as priority funding areas in the national

science, technology and innovation plan. In line with the World Health Organisation (WHO) Global

Action Plan for the Prevention and Control of NCDs including obesity 2013-2020 whereby, member

states agreed to reduce obesity growth to zero percent and premature mortality from NCDs by

twenty five percent by 2025, the Sultanate of Oman has adopted Health Vision 2050, an inter-

sectorial partnership involving all departments of government in a programme to combat the

emergence of obesity, diabetes and cardiovascular disease 41. Similarly, the Ministry of Health in

Bahrain aims to establish regional screening and well-being clinics by 2016 as part of national health

improvement strategy, which is also linked to economic vision 2030 of kingdom of Bahrain. A

national policy framework of laws, directives and regulations to improve food and drink labelling,

8

encourage healthy foods, completely stop the use of hydrogenated cooking oil and control of

advertising and marketing of unhealthy foods and reduce sedentary life style in adults by 10% to

reduce obesity levels. 42

Nutritional and lifestyle programmes: The Sultanate of Oman implemented a national nutrition

surveillance plan (2006-2010), to collect data about the indicators of nutrition 43. Similar national

nutrition surveillance programs are also run in Kuwait and Saudi Arabia. WHO’s office for Eastern

Mediterranean Region (EMRO) proposed a regional nutrition strategy in 2010 for 2010-2019 to

reduce obesity and diabetes in the region and asked all the countries of the region to develop their

own national strategies to suit their resources and needs. The Ministry of Health of the United Arab

Emirates formed a national committee in 2010 to develop a national strategy for reducing obesity

and diabetes. Qatar also set up a national committee for nutrition and physical activity in 2011 that

developed a 5-year plan (2011-16) to reduce obesity and overweight by 1%, increase physical activity

by 1%, increase fruit consumption by 10% and increase public awareness of nutrition and physical

activity by 5% per year 44. As part of nutrition health program, Bahrain has set up specialist clinics in

the country to tackle obesity, diabetes and hypertension in the society. Similarly, in addition to

public awareness campaigns, Kuwait set up a national committee for the prevention of obesity,

which aims to introduce healthy food into school canteens, educate pupils about nutrition and

encourage sport, although results from a recent RCT highlighted the difficulties of engagement with

these programs in the current era [44].

Bariatric surgery in the gulf region: It is not clear when bariatric surgery became common obesity

solution in the gulf region. What appears to be the first bariatric surgery paper was published in

1992 on the long term result of vertical banded gastroplasty 45. Controversial bariatric surgery on

obese children are being performed in Saudi Arabia, a morbidly obese (BMI= 41 kg/m2) Saudi boy

became the youngest to undergo bariatric surgery internationally at two and a half years old 46.

Children and adolescent between 5 to 21 years old can be eligible to have bariatric surgery if the

child BMI above 40 kg/m2, or 35 kg/m2 with an associated comorbidity such as diabetes, obstructive

sleep apnea, hypertension, and dyslipidemia. Additional eligibility criteria include failure to lose

clinically significant weight for six months on a diet and exercise plan, written informed

assent/consent and positive psychological evaluation 47.

The International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) estimated

Kuwait to be the second highest country in the percentage of bariatric surgery cases performed in

2011 among 50 nations. The top 20 countries in the prevalence of bariatric operations are listed in

table 2 48. In United Arab Emirates, specialist obesity treatment centres are present in ministry of

9

health hospitals and according to press, there are plans to establish children’s obesity surgery

departments within these centres. Obesity surgeries are on the rise with waiting times of up to 4

months in UAE.

An increasingly popular recent alternative to bariatric surgery is removable, swallowable balloons

such as the Obalon (Obalon Therapeutics, California) launched in Saudi Arabia in 2014 by the

Alsultan Saudi Medical Company which can be inflated in the stomach to give the sensation of

satiety 50. In trials in Saudi Arabia, participants lost 8-12 kg in three months 50.

The local and public initiatives for weight loss and adoption of healthier lifestyles in the GCC

countries are encouraging. However, more concerted efforts and a joint action plan, which can be

modified before adoption to suit socioeconomic conditions of each GCC country, is needed to

combat the obesity epidemic.

Background to metabolic profiling and its application in obesity-related conditions

Metabolic profiling (also referred to as metabonomics / metabolomics) relies upon the use of high

resolution spectroscopic techniques, typically either nuclear magnetic resonance (NMR)

spectroscopy or mass spectrometry (MS), to generate comprehensive low molecular weight profiles

of biofluids, tissues or cells, which can be subsequently modelled and interpreted using multivariate

statistics. By comparison of metabolic profiles from samples obtained from groups of individuals

under different physiological or pathological conditions, for example atherosclerosis versus healthy,

metabolites that systematically differentiate two or more conditions can be obtained and used in a

diagnostic capacity or to improve mechanistic understanding. Although a few preliminary

metabonomic studies have been conducted to characterize the metabolic consequences of

atherosclerosis either in animal models 51 or in humans 52, 53, the technology has not yet been fully

exploited with respect to interrogating the mechanisms of cardiovascular disease. However, even

from the limited number of studies undertaken to date, evidence suggests that there is a definitive

metabolic signature associated with the disease and that this metabolic signature can be modulated

by dietary intervention.

Metabolic profiling has been successfully applied to several relevant facets of obesity including

characterization of the metabolic phenotype of adult and childhood obesity, exploring host-

microbiome interactions contributing to obesity and monitoring of therapeutic responses to both

nutritional and surgical interventions. The technology has much to offer in terms of elucidating

mechanisms and environmental contributions to obesity in the Gulf countries. In the following

10

paragraphs some key, but by no means exhaustive, examples of the use of the technology in obesity

are provided.

Phenotyping adult obesity: In a recent study in which a metabolic profiling strategy was applied to a

large scale epidemiological study on the impact of diet on hypertension (the INTERMAP study;

International Collaborative Study of Macronutrients, Micronutrients and Blood Pressure), a range of

urinary metabolites were identified that characterized the metabolic phenotypes of populations with

vastly differing blood pressure levels and lifestyles 54. This metabolome wide association study

(MWAS) approach harnesses the power of large epidemiological cohorts and high throughput

metabolic profiling to generate associations between metabolism, lifestyle and disease in complex

free-living populations. Amongst the candidate urinary biomarkers of obesity, approximately one

third were related to gut microbial products such as methylamines, phenylacetylglutamine and 4-

cresyl sulfate underscoring the potential role of the microbiota in obesogenesis 55. Other metabolic

correlates of high BMI included Kreb’s cycle intermediates, branched chain amino acids (BCAA) and

metabolites associated with muscle turnover. From the same population cohort, an MWAS analysis

of hypertension also indicated that the hypertensive phenotype was also partially driven by

metabolites involved in gut microbial metabolism or mammalian-microbial co-metabolism and

included hippurate (inversely associated with BP), phenylactetylglutamine and formate. Similarly,

the serum of obese phenotypes has been associated with a panel of metabolites including BCAA,

nonesterified fatty acids, organic acids, acylcarnitines, and phospholipids 56. Metabolic profiling has

also been used to investigate mechanisms underpinning obesity-related diseases, they include

lipidomic and metabonomic profiling to identify peroxisome proliferator-activated receptors (PPARs) 57 as potential targets for a number of diseases including diabetes and dyslipidaemia through their

effects on fatty acid oxidation pathways.

Phenotyping childhood obesity: A growing number of papers are reporting metabolic consequences

of obesity in children and adolescence, since it is clear that an early obesogenic environment has

worse consequences than acquiring a high BMI as an adult. Studies of obesity in children suggest

that the obese phenotype is similar to that observed in adults, particularly with respect to increased

serum levels of BCAA, sphingomyelins and acylcarnitines, indicative of changes in pathways involving

oxidative stress and β-oxidation 58. In one study, selective ion flow tube mass spectrometry (SIFT-MS)

was applied to measuring volatile organic acid profiles in children with non-alcoholic fatty liver

disease (NAFLD) with the aim of developing a non-invasive diagnostic assay. Children with NAFLD

were shown to have higher concentrations of trimethylamine, isoprene, ketone bodies and pentane

than healthy children 59.

11

Influence of the microbiota in obesity: Metabolic profiling is now widely accepted as a clinically

relevant tool for investigating disease and is gaining credibility in probing transgenomic interactions

between the gut microflora and the host. Collectively the available evidence points towards the gut

microbiota playing a significant role in conditions associated with cardiovascular health. One of the

most promising developments in this respect is the ability to statistically integrate metabolic profiles

with metagenomic profiles in order to extract correlations between particular bacterial species or

families and metabolites. This has been achieved using correlation methods 60 or bidirectional linear

projection methods 61 to derive core microbial-metabolite associations. There is much to be learned

from this line of investigation and a series of studies focussing on the effect of nutritional

interventions on metabolic profiles with respect to obesity and metabolic syndrome have shown

that it is possible to modify the metabolic signature relating to microbial metabolism, and to link this

to phenotypic changes, for example weight loss 62.

Mapping and monitoring nutritional strategies to reduce obesity: Human biofluid profiles are

responsive to nutritional changes and also show inter-individual differences in a wide variety of

metabolite classes (amino acids, phenolics, short chain fatty acids, organic acids, lipids and proteins)

in response to dietary challenges 63 suggesting opportunities for personalization of nutrition 64.

Metabolic profiling has been used to catalogue the effects of weight loss in adults after dieting and,

in addition to noting decreased serum concentrations of glucose and lipids, has also found reduced

blood levels of saturated fatty acids such as palmitic and stearic acid with palmitoleic acid being one

of the strongest correlates with weight loss 65. In general, nutritional approaches to weight loss

either utilize a global shift in diet, for example the Mediterranean Diet, or investigate specific dietary

components with functional activity. Metabolic profiling of Western diets indicate that high levels of

serum amino acids, BCAA, lysophosphocholines and carnitines are the major contributors to the

phenotype 66. Weight loss as a result of lifestyle change causes normalization of the

lysophosphatidylcholines and carnitine profiles 67. The literature is swamped with articles on

functional foods that are purported to enhance metabolism or aid weight loss. Some of these have

been investigated in humans using metabonomic methods, although very few of these studies have

been well powered. Examples include studies of the effects of plant-based extracts with associated

weight reduction, for instance consumption of black soybean peptides is associated with increased

serum betaine, benzoic acid, phenylalanine and lysophosphocholines together with decreased BCAA

and carnitines 68. Other examples include the beneficial metabolic changes in phospholipids

following consumption of dairy products, which was associated with lowering of insulin resistance

12

levels 69. Transgenomic interactions have been identified following the implementation of high fat

diets, with particular effect on the gut microbial products of choline metabolism such as

methylamines 70, whilst administration of pre- and pro-biotics have been shown to alter plasma lipids

favourably, in addition to inducing changes in a range of urinary gut microbial metabolites including

microbially modulated bile acids 71. New research indicates that in both germ free and antibiotic

models of microbial depletion, the bile acid profiles of several tissues, including that of the liver,

kidney and heart is significantly different from conventional animals, containing a substantially

higher percentage of tauro-conjugated bile acid species 72. This indicates that the presence of

microbiota influences the global metabolism of the host and may impact on the development of

heart disease and other metabolic disorders.

Mechanistic evaluation of surgical interventions: Bariatric surgery is increasingly utilized as a

therapeutic intervention for morbid obesity and is also known to cure type 2 diabetes in the majority

of cases. Metagenomic profiling of fecal samples post bariatric surgery has shown a shift towards

increased numbers of proteobacteria 13, and in separate studies focusing on the metabolite profile,

an increase in plasma 4-cresyl sulfate, a microbial metabolite known to be produced by several

species of Clostridia 73 was found. Other gut bacterial products were also shown to be modified by

bariatric surgery including urinary hippurate, trigonelline and 2-hydroxyisobutyrate 74 consistent with

a modified microbiome post-surgery. A study of laproscopic sleeve gastrectomy in six children and

adolescents (mean age 14.5 years) showed a conserved response across all children in reduction of

serum levels of sphingomyelins and methionine with upregulation of phenylalanine and glycero-

phospatidylcholine PCaaC38:5 75. The same group comparing obese adults undergoing sleeve

gastrectomy with a matched group on a hypocaloric diet showed similar profiles relating to weight

loss 76. Since type 2 diabetes typically resolves within 48 hours post bariatric surgery, whereas

significant weight loss takes some weeks to obtain, it has been hypothesized that the mechanisms

driving the diabetes resolution and weight loss are not exactly the same. A recent study by Lips et al

showed that a marked decrease in serum BCAA occurred following surgery but was not observed in

a control group of patients achieving equivalent weight loss using a hypocaloric diet 77. Animal

models have been used to explore the mechanisms by which bariatric surgery contributes to weight

loss and resolution of diabetes. Li et al showed profound changes in the metagenome and both the

urinary and fecal metabolomes of rats undergoing Roux-en-Y gastric bypass (RYGB) associating

changes in the gammaproteobacteria with production of metabolites from protein putrefaction (4-

cresyl sulfate, phenylalanylglycine), decreased urinary excretion of tricarboxylic cycle intermediates

(succinate, citrate, 2-oxoglutarate) and increased fecal excretion of gamma-aminoisobutyrate

13

(GABA), which is a metabolite with neuroactive properties 78. The same group also showed

differences between surgical- and diet-induced weight loss in a mouse model 79.

As yet, there are few metabolic profiling studies being applied to obesity and cardiometabolic risk

research in the Gulf countries. Of the few published studies, a targeted mass spectrometric strategy

was used in Qatar to investigate pre- and post-prandial states in response to fasting associated with

Ramadan and showed differences in response to short and long-term fasting, particularly in bile acid,

polyamine and acylcarnitine profiles 80. However, capacity for metabolic profiling, largely based on

mass spectrometry is growing across the Gulf region with academic centres such as Saudi and Qatar

adapting existing mass spectrometry infrastructure and acquiring new technology to characterize

the metabolic phenotype associated with obesity and to explore it’s relationship with gene-

environmental interactions. This investment in technology and people, together with the substantial

effort that has been expended into developing nutritional programmes to combat obesity forms the

cradle for what should be definitive research into the etiopathogenesis of obesity, with clear

potential for immediate clinical translation through the obesity and nutrition centres. Whilst obesity

in GCC countries results from the far-reaching socio-economic, genetic and environmental influences

that have coalesced into the evident obesogenicity in the region, the potential for increased

mechanistic research accompanied by its translational clinical management in these nations may

lead to novel targeted therapies for the local population but importantly can help produce the next

generation of treatments aimed at minimising the global effects of complex obesity and its co-

morbidities.

14

Tables:

Table 1: The top 10 countries for prevalence (%) of diabetes* (20-70 years), 2013 and 2035.

Country 2013 (%) Country 2035 (%)Tokelau 37.5 Tokelau 37.9Federated States of Micronesia 35.0 Federated States of Micronesia 35.1Marshall Islands 34.9 Marshall Islands 35.0Kiribati 28.8 Kiribati 28.9Cook Islands 25.7 Cook Islands 25.7Vanuatu 24.0 Saudi Arabia 24.5Saudi Arabia 24.0 Vanuatu 24.2Nauru 23.3 Nauru 23.3Kuwait 23.1 Kuwait 23.2Qatar 22.9 Qatar 22.8*comparative prevalence, adapted from the International Diabetes Federation. IDF diabetes atlas, 2013 28.

15

Table 2: Numbers of bariatric surgeries performed in 2011 as a percentage of the national population

Nations Total population Bariatric cases %1 Belgium 1,100,800 8,500 0.77222 Kuwait 2,818,042 4,626 0.16423 Sweden 9,453,000 8,500 0.08994 Israel 7,765,700 5,000 0.06445 Australia/New Zealand 23,061,120 12,000 0.0526 France 65,436,552 27,648 0.04237 Iceland 319,000 106 0.03328 Brazil 196,655,014 65,000 0.03319 USA/Canada 311,591,917 101,645 0.032610 Switzerland 7,907,000 2,566 0.032511 Chile 17269525 5,554 0.032212 Netherlands 16,696,000 5,000 0.029913 Portugal 10637000 3,028 0.028514 Saudi Arabia 28,082,541 7,000 0.024915 UAE 7,890,924 1,963 0.024916 Austria 8,419,000 2,081 0.024717 Finland 5,387,000 1,056 0.019618 Mexico 114,800,000 19,600 0.017119 Spain 46,240,000 7,850 0.01720 UK 62,641,000 10,000 0.016Adapted from IFSO, 2013 48

16

REFERENCES

1 McKinsey Global Institute. (2014). Overcoming obesity: An initial economic analysis [WWW document]. http://www.mckinsey.com/insights/economic_studies/how_the_world_could_better_fight_obesity2 Cauchi S, Stutzmann F, Cavalcanti-Proença C, et al. Combined effects of MC4R and FTO common genetic variants on obesity in European general populations. J Mol Med. 2009; 87: 537-46.3 Krauss RM, Winston MF, Fletcher BJ, Grundy SM. Obesity : impact on cardiovascular disease. Circulation. 1998; 98: 1472-76.4 Kurukulasuriya LR, Stas S, Lastra G, Manrique C, Sowers JR. Hypertension in obesity. Med Clin North Am. 2011; 95: 903-17.5 Nicholson JK, Lindon JC, Holmes E. 'Metabonomics': understanding the metabolic responses of living systems to pathophysiological stimuli via multivariate statistical analysis of biological NMR spectroscopic data. Xenobiotica. 1999; 29: 1181-9.6 Villanueva-Millan MJ, Perez-Matute P, Oteo JA. Gut microbiota: a key player in health and disease. A review focused on obesity. J Physiol Biochem. 2015.7 Dhurandhar EJ, Keith SW. The aetiology of obesity beyond eating more and exercising less. Best Practice & Research Clinical Gastroenterology. 2014; 28: 533-44.8 Ley RE, Backhed F, Turnbaugh P, Lozupone CA, Knight RD, Gordon JI. Obesity alters gut microbial ecology. Proc Natl Acad Sci U S A. 2005; 102: 11070-5.9 Turnbaugh PJ, Hamady M, Yatsunenko T, et al. A core gut microbiome in obese and lean twins. Nature. 2009; 457: 480-4.10 Backhed F, Manchester JK, Semenkovich CF, Gordon JI. Mechanisms underlying the resistance to diet-induced obesity in germ-free mice. Proc Natl Acad Sci U S A. 2007; 104: 979-84.11 Tringe SG, von Mering C, Kobayashi A, et al. Comparative Metagenomics of Microbial Communities. Science. 2005; 308: 554-57.12 Wang Y, Lawler D, Larson B, et al. Metabonomic investigations of aging and caloric restriction in a life-long dog study. J Proteome Res. 2007; 6: 1846-54.13 Zhang H, DiBaise JK, Zuccolo A, et al. Human gut microbiota in obesity and after gastric bypass. Proceedings of the National Academy of Sciences. 2009.14 Barker DJ, Hales CN, Fall CH, Osmond C, Phipps K, Clark PM. Type 2 (non-insulin-dependent) diabetes mellitus, hypertension and hyperlipidaemia (syndrome X): relation to reduced fetal growth. Diabetologia. 1993; 36: 62-7.15 Neel JV. Diabetes Mellitus: A “Thrifty” Genotype Rendered Detrimental by “Progress”? American Journal of Human Genetics. 1962; 14: 353-62.16 Unicef & World Health Organization (WHO). Low birthweight: Country, regional and global estimates. . 2004.17 Musaygar A, Mistry N. Obesity in the arab gulf countries: An annotated bibliography.: 2001.18 Schäfer K. (2013). Urbanization and urban risks in the arab region. [WWW document]. http://www.preventionweb.net/files/31093_habitataqabaurbanresillience.pdf19 Mosaad AT, Younis MZ. Health policies and intervention strategies: a description of current issues and approaches to care of the public health and health care system in the United Arab emirates. J Health Care Finance. 2014; 40: 86-100.20 Klautzer L, Becker J, Mattke S. The curse of wealth – Middle Eastern countries need to address the rapidly rising burden of diabetes. International Journal of Health Policy and Management. 2014; 2: 109-14.21 Badran M, Laher I. Obesity in Arabic-Speaking Countries. Journal of Obesity. 2011; 2011: 9.

17

22 Memish ZA, El Bcheraoui C, Tuffaha M, Robinson M, Daoud F, Jaber S. Obesity and Associated Factors - Kingdom of Saudi Arabia, 2013. Preventing Chronic Disease. 2014; 11: E174.23 Ahlqvist E, Ahluwalia TS, Groop L. Genetics of type 2 diabetes. Clin Chem. 2011; 57: 241-54.24 Ministry of Health (Saudi Arabia), World Health Organization (WHO). Saudi arabia STEPS noncommunicable disease risk factors survey 2005.25 Ministry of Health. Survey of Health Information in the Kingdom of Saudi Arabia. . 2013.26 Ng SW, Zaghloul S, Ali HI, Harrison G, Popkin BM. The prevalence and trends of overweight, obesity and nutrition-related non-communicable diseases in the Arabian Gulf States. Obes Rev. 2011; 12: 1-13.27 Kahn SE, Hull RL, Utzschneider KM. Mechanisms linking obesity to insulin resistance and type 2 diabetes. Nature. 2006; 444: 840-46.28 International Diabetes Federation. IDF Diabetes Atlas. Brussels, Belgium 2013.29 Mabry RM, Reeves MM, Eakin EG, Owen N. Gender differences in prevalence of the metabolic syndrome in Gulf Cooperation Council Countries: a systematic review. Diabet Med. 2010; 27: 593-7.30 Bener A, Saleh NM. The impact of socio-economic, lifestyle habits, and obesity in developing of pregnancy-induced hypertension in fast-growing country: global comparisons. Clin Exp Obstet Gynecol. 2013; 40: 52-7.31 Deckelbaum RJ, Williams CL. Childhood obesity: the health issue. Obes Res. 2001; 9 Suppl 4: 239S-43S.32 de Onis M, Blossner M. Prevalence and trends of overweight among preschool children in developing countries. Am J Clin Nutr. 2000; 72: 1032-9.33 El Mouzan MI, Foster PJ, Al Herbish AS, et al. Prevalence of overweight and obesity in Saudi children and adolescents. Annals of Saudi Medicine. 2010; 30: 203-08.34 Boodai SA, Cherry LM, Sattar NA, Reilly JJ. Prevalence of cardiometabolic risk factors and metabolic syndrome in obese Kuwaiti adolescents. Diabetes, Metabolic Syndrome and Obesity: Targets and Therapy. 2014; 7: 505-11.35 Musaiger AO, Al-Mannai M, Zagzoog N. Association between food intake frequency and obesity among adolescent girls in Saudi Arabia. Int J Adolesc Med Health. 2014; 26: 145-7.36 Ibrahim H, Awadhi AA, Shaban S, Nair SC. Can our residents carry the weight of the obesity crisis? A mixed methods study. Obes Res Clin Pract. 2014.37 Ashrafian H, Darzi A, Athanasiou T. Bariatric surgery - can we afford to do it or deny doing it? Frontline gastroenterology. 2011; 2: 82-89.38 Sweileh WM, Zyoud SeH, Al-Jabi SW, Sawalha AF. Quantity and quality of obesity-related research in Arab countries: assessment and comparative analysis. Health Research Policy and Systems. 2014; 12: 33-33.39 Musaiger AO, Al Hazzaa HM, Al-Qahtani A, et al. Strategy to combat obesity and to promote physical activity in Arab countries. Diabetes, Metabolic Syndrome and Obesity: Targets and Therapy. 2011; 4: 89-97.40 Behbehani K. Kuwait National Programme for Healthy Living: first 5-year plan (2013-2017). Med Princ Pract. 2014; 23 Suppl 1: 32-42.41 Kumanyika S, Libman K, Garcia A. (2013). Strategic action to combat the obesity epidemic. Report of the Obesity Working Group 2013 [WWW document]. file://icnas4.cc.ic.ac.uk/ma2412/27425_WISH_Obesity_Report_web[14].pdf42 Minstry of Health Kingdom of Bahrain. Bahrain's Health Agenda: Healthy Improvment Strategy (2011-2014). . 2012.43 Ministry of Health Sultanate of Oman. National Food and Nutrition Surveillance System: Methods and Procedure.: 2009.44 Ministry of Health Qatar. National Health Strategy 2011-2016.45 Mofti AB, Al-Saleh MS. Bariatric surgery in Saudi Arabia. Ann Saudi Med. 1992; 12: 440-5.

18

46 Mohaidly MA, Suliman A, Malawi H. Laparoscopic sleeve gastrectomy for a two-and half year old morbidly obese child. International Journal of Surgery Case Reports. 2013; 4: 1057-60.47 Alqahtani AR, Antonisamy B, Alamri H, Elahmedi M, Zimmerman VA. Laparoscopic sleeve gastrectomy in 108 obese children and adolescents aged 5 to 21 years. Ann Surg. 2012; 256: 266-73.48 Buchwald H, Oien DM. Metabolic/bariatric surgery worldwide 2011. Obes Surg. 2013; 23: 427-36.49 Almazeedi S, Al-Sabah S, Al-Mulla A, et al. Gastric Histopathologies in Patients Undergoing Laparoscopic Sleeve Gastrectomies. Obesity Surgery. 2013; 23: 314-19.50 Mion F, Ibrahim M, Marjoux S, et al. Swallowable Obalon(R) gastric balloons as an aid for weight loss: a pilot feasibility study. Obes Surg. 2013; 23: 730-3.51 Martin JC, Canlet C, Delplanque B, et al. 1H NMR metabonomics can differentiate the early atherogenic effect of dairy products in hyperlipidemic hamsters. Atherosclerosis. 2009; 206: 127-33.52 Vallejo M, Garcia A, Tunon J, et al. Plasma fingerprinting with GC-MS in acute coronary syndrome. Anal Bioanal Chem. 2009; 394: 1517-24.53 Brindle JT, Antti H, Holmes E, et al. Rapid and noninvasive diagnosis of the presence and severity of coronary heart disease using 1H-NMR-based metabonomics. Nat Med. 2002; 8: 1439-44.54 Holmes E, Loo RL, Stamler J, et al. Human metabolic phenotype diversity and its association with diet and blood pressure. Nature. 2008; 453: 396-400.55 Elliott P, Posma JM, Chan Q, et al. Urinary metabolic signatures of human adiposity. Science Translational Medicine. 2015; 7: 285ra62.56 Rauschert S, Uhl O, Koletzko B, Hellmuth C. Metabolomic biomarkers for obesity in humans: a short review. Ann Nutr Metab. 2014; 64: 314-24.57 Ament Z, Masoodi M, Griffin JL. Applications of metabolomics for understanding the action of peroxisome proliferator-activated receptors (PPARs) in diabetes, obesity and cancer. Genome Med. 2012; 4: 32.58 Wahl S, Yu Z, Kleber M, et al. Childhood obesity is associated with changes in the serum metabolite profile. Obes Facts. 2012; 5: 660-70.59 Alkhouri N, Cikach F, Eng K, et al. Analysis of breath volatile organic compounds as a noninvasive tool to diagnose nonalcoholic fatty liver disease in children. Eur J Gastroenterol Hepatol. 2014; 26: 82-7.60 Waldram A, Holmes E, Wang Y, et al. Top-down systems biology modeling of host metabotype-microbiome associations in obese rodents. J Proteome Res. 2009; 8: 2361-75.61 Li M, Wang B, Zhang M, et al. Symbiotic gut microbes modulate human metabolic phenotypes. Proceedings of the National Academy of Sciences. 2008; 105: 2117-22.62 Dumas ME, Wilder SP, Bihoreau MT, et al. Direct quantitative trait locus mapping of mammalian metabolic phenotypes in diabetic and normoglycemic rat models. Nat Genet. 2007; 39: 666-72.63 Heinzmann SS, Merrifield CA, Rezzi S, et al. Stability and robustness of human metabolic phenotypes in response to sequential food challenges. J Proteome Res. 2012; 11: 643-55.64 Qi L. Personalized nutrition and obesity. Ann Med. 2014; 46: 247-52.65 Perez-Cornago A, Brennan L, Ibero-Baraibar I, et al. Metabolomics identifies changes in fatty acid and amino acid profiles in serum of overweight older adults following a weight loss intervention. J Physiol Biochem. 2014; 70: 593-602.66 Bouchard-Mercier A, Rudkowska I, Lemieux S, Couture P, Vohl MC. The metabolic signature associated with the Western dietary pattern: a cross-sectional study. Nutr J. 2013; 12: 158.67 Reinehr T, Wolters B, Knop C, et al. Changes in the serum metabolite profile in obese children with weight loss. Eur J Nutr. 2015; 54: 173-81.68 Kim MJ, Yang HJ, Kim JH, et al. Obesity-Related Metabolomic Analysis of Human Subjects in Black Soybean Peptide Intervention Study by Ultraperformance Liquid Chromatography and Quadrupole-Time-of-Flight Mass Spectrometry. Journal of Obesity. 2013; 2013: 11.

19

69 Nestel PJ, Straznicky N, Mellett NA, et al. Specific plasma lipid classes and phospholipid fatty acids indicative of dairy food consumption associate with insulin sensitivity. Am J Clin Nutr. 2014; 99: 46-53.70 Fearnside JF, Dumas ME, Rothwell AR, et al. Phylometabonomic patterns of adaptation to high fat diet feeding in inbred mice. PLoS One. 2008; 3: e1668.71 Martin FP, Sprenger N, Yap IK, et al. Panorganismal gut microbiome-host metabolic crosstalk. J Proteome Res. 2009; 8: 2090-105.72 Swann JR, Want EJ, Geier FM, et al. Systemic gut microbial modulation of bile acid metabolism in host tissue compartments. Proc Natl Acad Sci U S A. 2011; 108 Suppl 1: 4523-30.73 Mutch DM, Fuhrmann JC, Rein D, et al. Metabolite profiling identifies candidate markers reflecting the clinical adaptations associated with Roux-en-Y gastric bypass surgery. PLoS One. 2009; 4: e7905.74 Calvani R, Miccheli A, Capuani G, et al. Gut microbiome-derived metabolites characterize a peculiar obese urinary metabotype. Int J Obes (Lond). 2010; 34: 1095-8.75 Oberbach A, von Bergen M, Bluher S, Lehmann S, Till H. Combined serum proteomic and metabonomic profiling after laparoscopic sleeve gastrectomy in children and adolescents. J Laparoendosc Adv Surg Tech A. 2012; 22: 184-8.76 Oberbach A, Bluher M, Wirth H, et al. Combined proteomic and metabolomic profiling of serum reveals association of the complement system with obesity and identifies novel markers of body fat mass changes. J Proteome Res. 2011; 10: 4769-88.77 Lips MA, Van Klinken JB, van Harmelen V, et al. Roux-en-Y gastric bypass surgery, but not calorie restriction, reduces plasma branched-chain amino acids in obese women independent of weight loss or the presence of type 2 diabetes. Diabetes Care. 2014; 37: 3150-6.78 Li JV, Ashrafian H, Bueter M, et al. Metabolic surgery profoundly influences gut microbial-host metabolic cross-talk. Gut. 2011; 60: 1214-23.79 Seyfried F, Li JV, Miras AD, et al. Urinary phenotyping indicates weight loss-independent metabolic effects of Roux-en-Y gastric bypass in mice. J Proteome Res. 2013; 12: 1245-53.80 Mathew S, Krug S, Skurk T, et al. Metabolomics of Ramadan fasting: an opportunity for the controlled study of physiological responses to food intake. J Transl Med. 2014; 12: 161.

20