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Lipids

Lipids. Composed of C, H and few O Basic unit is fatty acid (glyceride) Triglyceride is the major form of lipid = 3 fatty acids Fats and oils Monounsaturated Fatty Acids Polyunsaturated Fatty Acids Saturated Fatty Acids Essential Fatty Acids Energy yielding (9 kcal /gm).

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Lipids

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  1. Lipids • Composed of C, H and few O • Basic unit is fatty acid (glyceride) • Triglyceride is the major form of lipid = 3 fatty acids • Fats and oils • Monounsaturated Fatty Acids • Polyunsaturated Fatty Acids • Saturated Fatty Acids • Essential Fatty Acids • Energy yielding (9 kcal /gm)

  2. Sources of Dietary Lipids

  3. Properties of Lipids • Do not readily dissolve in water • Fats are solid at room temperature • Oils are liquid at room temperature • Triglycerides are the main form of lipids in food and body (storage) • Energy dense (9 kcal /gm)

  4. omega end alpha end Note that all carbons have two hydrogens – this is a fully saturated fatty acid. The building block of lipids are fatty acids 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 H H H H H H

  5. (Ester bond) Glycerol + 3 FA’s Triglyceride + 3 H20 Triglycerides H H--C--OH H--C--OH H--C--OH H O HO-C-R O HO-C-R O HO-C-R H O H--C--O--C-- O H--C--O--C-- O H--C--O--C-- H R + H2O + R + H20 R + H20

  6. esterification desterfication Triglycerides H H--C--OH H--C--OH H--C--OH H Fatty Acid Fatty Acid Fatty Acid H O H--C--O--C-- O H--C--O--C-- O H--C--O--C-- H Fatty Acid + Fatty Acid Fatty Acid

  7. omega end alpha end When two Hs are lost from two adjacent Carbons, a double bond is formed. This is an unsaturated fatty acid. Monounsaturated Fatty Acid Structure 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 H H H H H H

  8. omega end alpha end Two or more double bonds results in a polyunsaturated fatty acid. Polyunsaturated Fatty Acid Structure 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

  9. The more double bonds, the lower the melting point of a fat/oil • Beef fat or lard has a large amount of saturated fatty acids that are long. It is solid at room temperature. • Butter has about the same number of saturated as unsaturated fatty acids. Butter is beginning to melt at room temperature. • Vegetable oil is 100% unsaturated fatty acids. It is liquid at room temperature and will solidify at around –5 °F. • What about vegetable shortening?????

  10. The chain length has an effect on how liquid a fat/oil is at room temperature • Long chain FA • > 12 Carbons • Medium chain FA • 6 - 10 Carbons • Short chain FA • < 6 Carbons

  11. Hydrogenation of Fatty Acids • Process used to solidify an oil • Addition of H to C=C double bonds • Formation of trans fatty acid

  12. Health Dangers of Excessive Trans Fatty Acid • Raises LDL • Lowers HDL • Increases risk for heart disease • Current intake is~3% of total kcals • Soon to be on food labels

  13. Minimize Intake of Trans Fatty Acid • Limit use of hydrogenated fats • partially hydrogenated vegetable oil • Limit deep-fried foods • Limit high fat baked goods • Limit use of non-dairy creamers

  14. Essential Fatty Acids • Body can only make double bonds after the 9th carbon from the omega end • Needed for immune function, vision, cell membrane, and production of hormone-like compounds

  15. omega end alpha end 1st double bond is located on the 3rd carbon from the omega end Essential Fatty Acid; Omega-3 (alpha-linolenic acid) 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

  16. Omega-3 Fatty Acids • Primarily from fish oil • Also found in canola or soybean oil • Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are related • Metabolized to form eicosanoids • Recommend intake of ~2 servings of fish per week

  17. Omega 3 (Alpha-linolenic acid, C18:3) 2C 2H Eicosapentaenoic acid (EPA, C20:5) 2C 2H Docosahexaenoic acid (DHA, C22:6) Eicosanoids

  18. omega end alpha end 1st double bond is located on the 6th carbon from the omega end Essential Fatty Acid Omega-6 (alpha-linoleic acid) 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

  19. Omega-6 Fatty Acid • Found in vegetable oils • Only need ~ 1 tablespoon a day • Arachidonic acid can be made from omega-6 • Metabolized to form eicosanoids

  20. Omega 6 (linoleic acid, C18:2) 2C 2H Dihomo-gamma-linolenic acid (C20:3) 2H Arachidonic acid (C20:4) Eicosanoids

  21. Eicosanoids • Eicosanoids are a group of hormone-like compounds • Regulators of blood pressure, childbirth, clotting, immune responses, inflammatory responses, & stomach secretions • By-pass the blood stream and work in the area of origin

  22. Eicosanoids Have Different Effects • Omega-6 eicosanoids; Archidonic acid • increase blood cot • increase inflammatory responses • Omega-3 eicosanoids, DHA, EPA • decrease blood clotting • reduces heart attack • excess may cause hemorrhagic stroke??? • Eicosanoid has different effect on different tissues

  23. Signs and Symptoms of Essential Fatty Acids Deficiency • Flaky, itchy skin • Diarrhea • Infections • Retarded growth and wound healing • Anemia

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