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The Macronutrients - Lipids

The Macronutrients - Lipids. Chapter 1. Lipids. Lipid is a general term for a heterogeneous group of compounds. Oils, fats, waxes, and related compounds Simple lipids Compound lipids Derived lipids. Lipids. Functions Provide energy Protect vital organs Provide insulation from the cold

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The Macronutrients - Lipids

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  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 • 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. Hydrogenation • 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 – 3rd position • Linolenic acid • Omega-6 FA – 6th 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

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