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Understanding Lipids: Role in Body and Health Effects

Explore lipids - triglycerides, phospholipids, sterols, and their role in the body. Learn about fats in food sources, digestion, and health effects. Understand cholesterol, essential fatty acids, and lipid transport for overall well-being.

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Understanding Lipids: Role in Body and Health Effects

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  1. Lipids Triglycerides Fats and oils Phospholipids Lecithin Sterols Cholesterol

  2. Objectives • After reading Chapter 4, class discussion and case study work, you will be able to • Describe the role of lipids in the body • Identify food sources of fats • Discuss lipid digestion, absorption and transport • Calculate calories from fat

  3. Objectives • Identify types (classification) of lipids • Discuss the health related effects of lipids • Blood lipid profile • Omega fatty acids • Trans fatty acids • Hydrogenation

  4. Triglycerides 4

  5. glycerol Triglycerides

  6. Triglycerides • glycerol + 3 fatty acids  triglyceride

  7. Fatty Acids Length of fatty acid 18-24 carbons in length Degree of Saturation Saturated fatty-acid Monounsaturated fatty-acid Polyunsaturated fatty-acid

  8. Fatty Acids • Point of unsaturation • Location of double bonds • Omega number • Omega-3 fatty acid • Omega-6 fatty acid

  9. Triglycerides • Degree of saturation determines: • Firmness • Stability • Oxidation • Antioxidants

  10. Rancidity • Definition: Deterioration of fat; resulting in undesirable flavor/odor • Flavor Reversion-soy oil; Cu, Fe • Hydrolytic: Separation of glycerol from fatty acids • Short chain fatty acids • Butyric fatty acid; butter • Oxidative: Loss of hydrogen in presence of air/heat • Oxidation of double bonds • Polyunsaturated fatty acids

  11. Trans Fats • Degree of unsaturation revisited • Hydrogenation • Cis vs. trans-fatty acids • Trans fat occurs naturally in meat and dairy foods • Conjugated linoleic in milk • Possibly positive for heart health

  12. p. 108 NRAEF

  13. Phospholipids

  14. Phospholipids • Phospholipids in foods-Lecithin • Roles of phospholipids • Plasma membrane • Emulsifiers

  15. Phospholipids

  16. Sterols • Found in plants and animals • Cholesterol is most abundant • Found in animals only • Found in every cell in man’s body • Body makes ~700mg/day • Dietary intake 200-400mg/day

  17. Dietary Cholesterol

  18. Sterols • Roles of sterols • Manufacture bile acids • Make hormones • Estrogen and testosterone • Make adrenal hormones • Make Vitamin D • Maintain cell membranes

  19. Fat Digestion • Hydrolysis • Triglycerides  monoglycerides, fatty acids, glycerol

  20. Fat Digestion • Mouth • Melting • Lingual Lipase • Stomach • Churning and mixing • Gastric Lipase

  21. Fat Digestion • Small intestine • Fat triggers the release of hormone • Cholecystokinin (CCK) • Gallbladder releases bile • Bile emulsifies fat so it can be more fully digested • Pancreatic lipase • Intestinal lipase

  22. Fat Digestion

  23. Enterohepatic circulation How bile travels through the body Fat Digestion

  24. Fat DigestionOverview

  25. p.152 5-17

  26. Lipid Transport • Lipoproteins • Chylomicrons • VLDL = very-low-density lipoproteins • LDL = low-density lipoproteins • HDL = high-density lipoproteins

  27. Lipid Transport

  28. Lipid Transport • Lipoproteins and health • LDL: carries cholesterol from liver to the cells of the body • High=Less healthy • HDL: carries cholesterol from the cells back to the liver • High=More healthy

  29. Roles of Triglycerides • Fat stores • Energy • Protection • Insulation • Provide essential fatty acids

  30. Essential Fatty Acids • Linoleic acid and the omega-6 family • Arachidonic acid • Linolenic acid and the omega-3 family • Alpha omega 3 fatty acids • Marine omega 3 fatty acid • EPA =eicosapentaenoic acid • DHA = docosahexaenoic acid

  31. Essential Fatty Acids

  32. Health Effects of Lipids • Blood lipid profile • Cholesterol=<200mg/dL • LDL=<100 • HDL=>60 • TG=<150 • Risks from saturated fats, trans fats, cholesterol • Benefits from polyunsaturated fats monosaturated, omega-3

  33. Health Effects of Lipids • Risks from trans fats • Alter blood cholesterol like saturated fats • Raise LDL cholesterol • Lower HDL cholesterol at high intakes • Increase inflammation & insulin resistance • AI = 5 gm/day • Risks from cholesterol • Not as implicated as saturated or trans fats • Beware cholesterol sensitivity • Limit intake <300 mg/day

  34. Health Effects of Lipids • Benefits from monounsaturated fats and polyunsaturated fats • Olive oil (monounsaturated) • Lowers LDL and total cholesterol • Lowers blood clotting factors • Lowers blood pressure • Provides phytochemicals which act as antioxidants

  35. Health Effects of Lipids • Benefits from omega-3 fats • Prevent arrhythmias • Lower blood pressure • Improve blood vessel function • May ease inflammation • Prevent repeat heart attack • 1 gm supplement daily for 3 years • Balance omega-6 and omega-3 intakes

  36. Recommended Intakes of Fat • DRI: 20-35% of energy intake • Cholesterol: 200-300 mg/day • Linoleic acid AI • 5% - 10% of energy intake • Linolenic acid AI • 0.6 - 1.2% of energy intake

  37. Guidelines to Groceries • Limit whole milk and milk products • Use vegetables, fruits, and grains • Avoid invisible fat • Avoid tropical oils • Use low fat meats and Alternatives

  38. Fat Distribution in Diet

  39. p. 162 Fig 5-23

  40. Beware the Label • “0 Trans Fat” – can still contain up to 0.5 grams • Look for “partially hydrogenated vegetable oil” or “vegetable shortening” • IOM recommends trans fat intake be “as low as possible”

  41. Fat Substitutes • “New” vegetable oils from “new” seed • Soybean & other seeds with very low levels of linolenic acid • More stable but less omega-3 fatty acid • Fat substitues • Z-Trim made from corn, soy, oat fiber • Oatrim made from whole oats • Fat replacers • Artificial fats • Olestra

  42. High-Fat Foods • Changing guidelines for fat intake

  43. High-Fat Foods • Cook with olive oil or canola oil • Monounsaturated fatty acids • Nibble on nuts • Omega-3 polyunsaturated fatty acids • Feast on fish • Marine omega-3 PUFA • But beware of mercury • Limit fatty meats, whole milk products, and tropical oils

  44. High-Fat Foods • Limit hydrogenated fat foods • Fried foods (fried in solid fats) • Fast foods (prepared in partially hydrogenated oils/fats • Commercial baked goods • Snack foods

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