1. The Macronutrients - Lipids Chapter 1

2. Lipids  Lipid is a general term for a heterogeneous group of compounds. Oils, fats, waxes, and related compounds Simple lipids Compound lipids Derived lipids

3. Lipids Functions  Provide energy  Protect vital organs  Provide insulation from the cold  Transport the fat-soluble vitamins A, D, E, and K

4. Lipids  Simple lipids Neutral fats – consist primarily of triacylglycerols Triglycerides Major storage form of fat in adipose cells

5. Triglycerides C,H,O Composed of 3 fatty acids (FA) Glycerol molecule TG vary in the type of FA and their bonding pattern FA vary in the number and arrangement of double bonds Usually even number C

6. Acetic Acid

7. Triglyceride

8. Fatty Acids  Saturated fatty acids  Single covalent bonds between carbon atoms  Covalent bonds share electrons  All of the remaining bonds attach to hydrogen.

9. Fatty Acids  Unsaturated fatty acids  One or more double bonds along the main carbon chain. Monounsaturated fatty acid - one double bond. Polyunsaturated fatty acid - two or more double bonds.

10. Fatty Acids Stearic acid, an 18-carbon saturated fatty acid

11. Fatty Acids Oleic acid, an 18-carbon monounsaturated fatty acid

12. Lipids Stability Oxygen exposure causes spoilage-rancid PUFA’s spoil more easily Increase saturation Hydrogenation Prolongs shelf life – prevents oxidation Alters texture – liquids → solids

13. Hydrogenation

14. Trans-Fatty Acids Changed from cis to trans configuration and act like saturated fats in the body Partial hydrogenation Higher melting point

15. Trans-Fatty Acids

16. Dietary Lipids Typical daily intake (< 30% total kcals) Should consist of: 65% animal lipids 35% vegetable lipids <10% saturated Little or no trans fat

17. Essential Fatty Acids Double bonds Omega number Position of first double bond Omega-3 FA – 3 rd position Linolenic acid Omega-6 FA – 6 th position Linoleic acid Body can only make double bonds after the 9th carbon from the omega end

18. Linolenic Acid – omega-3

19. Fatty Acids-omega-6 Linoleic acid, an 18-carbon polyunsaturated fatty acid

20. Essential Fatty Acids Functions Immune function, Vision Cell membrane, and Production of hormone-like compounds

21. Essential Fatty Acids Omega-3 Omega 6 Alpha-linolenic acid Linolenic acid DHA EPA Arachidonic Acid (docosahexanoic (eicosapentaenoic acid) acid)

22. Essential Fatty Acids DHA, EPA Decrease blood clotting Care must be taking when supplementing DHA, EPA when on anticoagulant medication Or when having surgery Reduce heart attacks Fish oils have an anti-arrhythmic effect on myocardial tissue. Decrease inflammation, pain

23. Compound Lipids Phospholipids Built on a glycerol backbone One or more FA Phosphorus group Nitrogenous base Found in body, cell structures Synthesized by the body as needed liver Not needed in diet, not essential

24. Compound Lipids Phospholipids Contain polar head groups Hydrophilic head (protein) Hydrophobic tail (two FA chains) Allows for movement of fat soluble substances Vitamins Hormones

25. Phospholipids

26. Compound Lipids Phospholipids Lecithin - 5% of lipids in diet Eggs Liver Soybeans Wheat germ Peanuts

27. Compound Lipids  Glycolipids:  Fatty acid bound with carbohydrate and nitrogen  Essential part of cell membranes

28. Glycolipids

29. Compound Lipids  Lipoproteins:  Proteins joined with triacylglycerols or phospholipids  Primary method of lipid transport

30. High, Low-Density Lipoprotein Cholesterol 5 types of lipoproteins exist Based on gravitational density Chylomicrons, VLDL, IDL, LDL and HDL Chylomicrons – fat droplets Long chain triacylglycerols Phospholipids Free fatty acids A,D,E,K

31. Chylomicron

32. Compound Lipids Lipoproteins Very low density lipoprotein (VLDL) Formed in liver 95% fat (60% triacylglycerol) Transports triacylglycerols to muscle, adipose Oxidation of VLDL and uptake of triglycerides into cell (lipoprotein lipase)

33. Compound Lipids Lipoproteins Low density lipoprotein (LDL) Contain less lipid than VLDL Carry most of the cholesterol (60-80%) Great attraction to cells of arterial walls

34. Cholesterol Lipoproteins High density lipoproteins Scavenger Reverse transport of cholesterol Delivers cholesterol to liver Bile Excretion through intestinal tract

35. Cholesterol Exogenous Dietary cholesterol (300 mg) Endogenous Cellular synthesis (70% in liver) 0.5 to 2.0 g/day Sufficient for body’s needs