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Lipids 3Phospholipids, Essential Fatty Acids,

LC-PUFA/Eicosanoids, Lipidperoxidation/Antioxidants

Question

Omega-3 fatty acids are

A. A form of trans fatty acidB. Converted in the body to arachidonic

acid

C. Synthesized de novo in the liver andsmall intestine

D. Found in certain PUFA-rich oils and cold-water fish

E. B and D only

Functions of Phospholipids

Component of cell membrane

Emulsifier Bile acids

Lecithins

Improves food products

Found in wheat germ, peanuts, yolks,soy beans, organ meat

Emulsifiers

Fig. 02.29 Essential Fatty Acids

Polyunsaturated fatty acids that must beconsumed in the diet since we cannotsynthesize

One key step missing cannot add a doublebond closer than 9 carbons from omega end ofthe molecule

Can add double bonds closer to alpha end ofmolecule

Consume precursors and add double bondscloser to alpha end and make longer

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Signs and Symptoms ofEssential Fatty Acids

Deficiency

Flaky, itchy skin

Diarrhea

Infections

Retarded growth and wound healing

Essential Fatty Acid- Omega-6 (linoleicacid)

omega end alpha end

1st double bond is located on the 6th carbonfrom the omega end

H H H H H H H H H H H H H O

H-C--C--C--C-- C--C =C--C--C=C--C--C--C--C--C--C--C--C-OH

H H H H H H H H H H H H H H H H H

Essential Fatty Acid- Omega-3 (alpha-linolenic acid)

omega end alpha end

1st double bond is located on the 3rd carbon

from the omega end

H H H H H H H H H H H H H H H H H O

H-C--C--C=C--C--C =C--C--C=C--C--C--C--C--C--C--C--C-OH

H H H H H H H H H H H

Essential Fatty AcidsOmega 6 Series

Linoleic acid 18:2n-6

Arach ido nic Acid 20:4n-6

Omega-3 Series

alpha-Linolenic acid 18:3n-3

DHA 22:6 n-3

(docosahexaenoic acid)

EPA 20:5n-3

(eicosapentaenoic acid

Adding Carbons and

double bonds occursin liver and a few other

tissues!!

Diet Sources

Soybean,

linseed,

borage oils,

others

Diet Sources

Most oils

including

soybean &

safflower oi ls,

chicken

Meat,

eggs,

some

fish

Fish and fish

oils

Arachidonic Acid

AA serves as a precursor for a variety of lipid-soluble compounds that function as localizedhormones.

The compounds collectively known aseicosanoids

Play a role in most physiological processes

Examples

Blood flow regulation, body temperature regulation,the birthing process, immune function, signaling in thebrain

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Eicosanoids Overproduction

Although important to many normal physiologicalprocesses

Eicosanoid overproduction by immune cells, etc.causes inflammation

Inflammation is implicated in number of diseases arthritis, asthma, heart disease, even some cancers

High amounts of AA in our cell membranes isproposed by some to contribute to greaterproduction of eicosanoids more inflammation Higher dietary intake of omega-6 FA and less of

omega-3 FA proposed to contribute to this Consuming more omega-3 fatty acids can have an

anti-inflammatory effect

Fig. 17.23

EPA competes

and d ecreases

product

formation

Health-related Effects

Arachidonic acid (Omega-6 ) Increases blood clotting

Increases inflammatory responses

DHA, EPA (Omega-3) Decrease blood clotting

Reduce heart attack

Decrease inflammation

Other: Lower triglycerides, rheumatoidarthritis, behavioral disorders

LNA

LNA

Sources of Safe Fish

The toxins, mercury and PCBs, canaccumulate in fish.

Look for safe sources

http://www.epa.gov/waterscience/fishadvice/advice.html

http://www.cfsan.fda.gov/~dms/admehg3.html

http://www.mercuryaction.org/fish/

LC-PUFA Easily Oxidized

Arrangement of two double bonds with a Cin between (1,4-pentadiene) susceptible tooxidation

Leads to rancidity in food stinky fish

Can cause oxidative stress in livingorganisms

Prevented by antioxidants!!

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Prevention of Rancidity

Hydrogenation decreases the #of

double bonds Addition of antioxidants prevent

oxidation vitamin E, also vitamin C

FDA approved synthetic antioxidants BHAand BHT

Phytochemicals fruits (blueberries,strawberries, pomegranates), green tea, redwine, dark chocolate Hypertension

Many Foods Advertise Presence ofAntioxidants

Dark Chocolate Comparison

Comparison of Chocolates

kcal total fat sat fat sugars

Ghirardelli squares 55 4 3 4

Hershey's extra dark 53 4 2 4

Dove Rich Dark Chocolate 37 2 1 3

Hershey's Rich Dark Kisses 26 1 1 2

Per Piece