1 / 64

LIPIDS

LIPIDS. Lipids: Definition. A family of compounds soluble in organic compounds but not in water. 3 classes of lipids: Triglycerides: 95 % of lipids in foods Phospholipids: e.g..: lecithin Sterols: e.g..: cholesterol. Lipids: Fats and Oils.

omer
Download Presentation

LIPIDS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. LIPIDS

  2. Lipids: Definition • A family of compounds soluble in organic compounds but not in water. • 3 classes of lipids: • Triglycerides: 95 % of lipids in foods • Phospholipids: e.g..: lecithin • Sterols: e.g..: cholesterol

  3. Lipids: Fats and Oils • Fats: those lipids that are solid at room temperature(70 degrees F) • beef fat, pork fat, etc... • Oils: those lipids that are liquid at room temperature(70 degrees F) • vegetable oils

  4. Lipids: Functions • Provide Calories: 9 Cal/ gram • Lipids carry fat soluble vitamins in food and in body • Vitamins A, D, E, K • Provide building material for body • adipose tissue, components of cell membranes, many hormones, nerve coverings

  5. Lipids: Functions (cont.) • Thermal insulation • 1/2 of fat is subcutaneous • Protection for organs • the rest of fat surrounds organs and protects them • Essential Fatty Acids: Linoleic and Linolenic Acids • abundant in plant oils and fish oils

  6. Triglycerides: Glycerol + 3 Fatty Acids • Glycerol: similar to sugar 3 carbons long • Fatty Acids: Can differ in two ways • Degree of saturation • Saturated: 0 double bonds • Monounsaturated: 1 double bonds • Polyunsaturated: 2 or more double bonds • Chain length: how many carbons long it is • 4-6 Carbons: short chain • 8-12 Carbons: medium chain • 14+ Carbons: long chain

  7. Saturated Fatty Acids • Raises blood cholesterol • Solid at room temperature • High in animal fats • Tropical plant fats • coconut oil, palm oil, cocoa oil

  8. Mono Unsaturated Fats • Lowers blood cholesterol • Lowers LDL - cholesterol • No effect on HDL - cholesterol • Liquid at room temperature • Olive oil, canola oil, peanut oil

  9. Polyunsaturated Fats • Lowers LDL-cholesterol • Lowers HDL-cholesterol • Vegetable oils • Fish oils

  10. Essential Fatty Acids • PUFA’s required in diet • Omega-6 PUFA’s - Linoleic acid • Omega-3 PUFA’s - Linolenic acid • 3-6 g/day (1 tsp veg. oil)

  11. Essential Fatty Acids • Deficiency Syndrome • Rare fat malabsorption in infants • Dermatitis, hair loss, poor wound healing

  12. Essential Fatty Acids • Functions • Component of phospholipids in cell membranes • Synthesis of Eicosanoids • Prostaglandins • Leukotrienes • Potent hormone-like chemicals

  13. Eicosanoid Functions • Regulate smooth muscle contractions • Regulate blood pressure • Regulate blood clotting

  14. Dietary Effects on Eicosanoids • Omega-6 PUFA (Veg Oils) • increase blood clotting • increase blood pressure • increases risk of heart disease

  15. Dietary Effects on Eicosanoids • Omega -3 PUFA’s (fish oils, canola) • decreases blood clotting • decreases blood pressure • decreases blood viscosity • decreases risk of heart disease

  16. Omega-3 fatty acids & heart disease • Prevent cardiac arrhythmias • Act as antithrombotic agents • Inhibit growth of atherosclerotic plaques • Act as antiinflammatory agent • Lower VLDL and increase HDL • Omega 3s could cut risk of second heart attack

  17. Omega 3 Animal Sources • Shellfish, sardines, albacore tuna, salmon, mullet, herring, trout, mackerel and anchovies

  18. Omega 3 Plant Sources • Canola oil, soybeans, flaxseed, walnuts, wheat germ

  19. Hydrogenation of Fatty Acids • Polyunsaturated fatty acids subject to oxidative rancidity • PUFAs are also liquid at room temperature • Hydrogenation makes them more saturated • This makes them resistant to oxidative rancidity • This makes them solid at room temperature • this also increases the amount of Trans-fatty acids

  20. Hydrogenation: trans-fatty acids • Trans-fatty acids are mistakes that happen with hydrogenation • Increase risk of heart disease • Elevate LDL-cholesterol and may lower HDL-cholesterol • What is better, butter or margarine? • MedlinePlus: Trans fat alternative may have its own problems

  21. CIS – TRANS Configuration

  22. Top Ten “Trans Fat” Foods • Spreads • Packaged foods • Soups • Fast Food • Frozen Food • Baked Goods • Chips and Crackers • Breakfast Food • Cookies and Candy • Toppings and DipsNo trans fat in new Crisco formula - Diet & Nutrition - MSNBC.com

  23. Which of the following statements regarding hydrogenation is FALSE? • It creates trans fats • It is the process of adding hydrogen bonds • It creates a heart healthy product

  24. Triglycerides: Fatty Acids • Rule of thumb: the more saturated, the more solid it is at room temperature • Also the longer the Fatty Acid, the more solid at room temperature • Safflower oil is mostly (74%) PUFA: liquid at room temperature • Beef fat is mostly (48%) Saturated: solid at room temperature

  25. Digestion of Fats • As fat enters the small intestine • Bile is secreted from the gall bladder into the small intestine • Bile is produced by the liver and stored in the gall bladder • Bile disperses fat into smaller fat droplets • Pancreatic enzymes break fat into 2 separate fatty acids and a monoglyceride

  26. Digestion of Fats • Fatty acids are arranged as lipoproteins for absorption and transport. • Chylomicron: A lipoprotein produced by cells lining the small intestine. • Composed of fatty acids surrounded by phospholipids and proteins • Soluble in water

  27. Digestion of Fats • Chylomicrons are absorbed by cells of the small intestine, then • Travel through the lymphatic system • Transferred to the bloodstream • Short- and medium-chain fatty acids are absorbed more quickly since they are not arranged into chylomicrons.

  28. Digestion of Fats • Triglycerides in the chylomicrons must be disassembled by lipoprotein lipase before they can enter body cells. • After entering body cells, triglycerides can be • Used immediately for energy • Used to make lipid-containing compounds • Stored in liver and muscle cells

  29. Phospholipids: • Similar to triglycerides • Glycerol + 2 fatty acids and 1 phosphate containing group. • e.g..: lecithin in egg yolks: emulsifies fat with water(vinegar) in a permanent emulsion in mayonnaise • Not an essential nutrient. Can be made in the body. • http://telstar.ote.cmu.edu/Hughes/tutorial/cellmembranes/

  30. Phospholipid Structure

  31. Sterols • Cholesterol: most recognized sterol • not an essential nutrient: can be made in the body from fats • Many hormones are also sterols • e.g..: estrogen: a predominantly female hormone is similar to cholesterol • Vitamin D is a sterol • is made from dehydro-cholesterol in skin with sun exposure

  32. Cholesterol absorption

  33. Serum cholesterol: Lipid Profile • Total serum cholesterol = cholesterol found in several particles in the blood. • Particles are called lipoproteins • chylomicrons: fat and cholesterol from digestion • very low density lipoproteins: VLDL; fat and cholesterol assembled in liver and sent into blood

  34. Serum cholesterol: Lipid Profile • low density lipoproteins: LDL; fat and cholesterol left over as VLDL drops off triglycerides to cells • Carries cholesterol towards tissues such as heart arteries • high levels increases risk of atherosclerosis

  35. Coronary Artery Disease

More Related