Lipids

1. Lipids FAT

2. Lipid Family • triglycerides • fats • oils • predominate in food and in the body • phospholipids • sterols • cholesterol

3. Lipids • energy storage • a lot of calories in a small space • generally insoluble in water • stored in special ways in the body • also function as structural components of cells

4. Fatty Acids fatty acids • made up of carbon, hydrogen, oxygen • more carbon and hydrogen so they supply more energy/gram • common building block for most lipids

5. the determining factor in whether to call a fatty acid saturated, unsaturated, monounsaturated, polyunsaturated, or trans fatty is determined by its chemical bonds and structure

6. Triglycerides • the form of lipid most found in food • 3 fatty acids + glycerol • major class of dietary lipid • flabby stuff most of us have is cells filled with triglycerides

7. Degree of Unsaturation • influences the firmness of fat • general impression in regards to food • liquid at room temp = unsaturated • solid at room temp – saturated (animal fats) • shorter the carbon chain, softer the fat at room temperature

8. stability • when exposed to oxygen, fat becomes rancid (oxidation) • saturated fats are more resistant • protection from oxidation • sealed, non-metallic, protected from light, refrigerated • addition of antioxidants • saturate by adding hydrogen molecules (hydrogenated)

9. Hydrogenation • also makes oils more manageable at room temp: peanut butter, hydrogenated vegetable oil

10. Trans-Fatty Acids • hydrogenated fatty acids • more saturated than natural vegetable oils • able to pack together more tightly • more solid are room temperature • behave more like saturated fatty acids • hidden in the reporting levels for unsaturated fatty acids

11. Phospholipids • minor portion of lipids in diet • lecithin is most common • found in eggs, liver, soy, peanuts • important role in cell membranes • lecithin is made in liver • not an essential nutrient

12. Sterols • important players: bile, sex hormones, Vit D • cholesterol is starting material • cholesterol • only found in food derived from animals • “good” or “bad “ cholesterol in not a type of cholesterol found in food • refers to the transportation of cholesterol in the blood • made in liver from carbs, protein, fat • 800-1500 milligrams/day

13. Lipid Digestion • mouth • slow start • some hard fats begin to melt • stomach • churning mixes chyme and breaks up fat into smaller droplets • expose fat to enzymes • little fat digestion actually takes place

14. small intestine • gall bladder releases bile • acts as an emulsifier • brings fats into water solution found in intestine • fully digested when enzyme lipase is encountered • once bile has completed its task • reabsorbed from intestine and recycled • trapped by fibers in large intestine and eliminated • reduces blood cholesterol

15. Lipid Absorption • small triglycerides can diffuse into intestinal cells, then absorbed into blood • larger long chain fatty acids merge in micelles (emulsified fat droplets) • allows for solubility in digestive fluids and movement to the intestinal cells • once inside cells, reassembly takes place into new triglycerides

16. Absorption of Fat Small intestine Stomach Monoglyceride Short-chain fatty acids Medium-chain fatty acids Micelle Glycerol Protein Chylomicrons Triglyceride Lacteal (lymph) Long- chain fatty acids Capillary network Chylomicron Blood vessels To blood To liver

17. Lipid Absorption • once inside intestinal cells • packed with protein into chylomicron • released into lymphatic system • enter bloodstream near the heart • carried by blood for use or storage • blood analysis indicates types of fat the diet has been delivering to the body

18. Absorption of Fat Small intestine Stomach Monoglyceride Short-chain fatty acids Medium-chain fatty acids Micelle Glycerol Protein Chylomicrons Triglyceride Lacteal (lymph) Long- chain fatty acids Capillary network Chylomicron Blood vessels To blood To liver

19. Lipid Transport • lipoproteins: fat transporters • chylomicrons • transport diet-derived lipids, mostly triglycerides • triglycerides are removed as they pass through the body • within 14 hours, most triglycerides are depleted • liver picks up the pieces and use or recycle the pieces

20. VLDL: very low density lipoprotein • transport lipids synthesized in live to other parts of the body • liver uses fatty acids in blood to make other fatty acids and cholesterol • triglycerides are removed from VLDL at they move through the body, becoming cholesterol dense • eventually become LDL

21. LDL: low density lipoproteins • cholesterol rich • are available to all tissue cells

22. HDL; high density lipoprotein • made by the liver to carry cholesterol from cells • back to the live and recycled or disposed

23. HDL or LDL • LDL: “bad” • associated with high risk of heart attack • HDL: “good: • protective effect for heart

24. Controlling LDL and HDL • lower LDL or raise HDL • weight control • unsaturated instead of saturated fat • fibers • phytochemicals • moderate alcohol consumption • physical activity

25. Essential Fatty Acids • linoleic acid/omega-6 • found in vegetable oils and meats • linolenic acid/omega-3 • fatty fish

26. Role of Lipids • provide energy • insulation • protection against shock • cell membrane structure • deficiencies • retarded growth, skin lesions, kidney and liver disorders

27. Lipid Metabolism • fat gives us 2X the energy of carbs and proteins • efficient storage in adipose tissue • food fat is converted to body fat by absorbing parts and putting back together again inside the cell • very little energy is needed Large central globule of (pure) fat

28. fat supplies 60% of body's energy during rest • more during activity • when needed fat (triglyceride) is dismantled and released as glycerol and fatty acids into the blood where it is easily accessible by the cells

29. Health Effects • heart disease • elevated blood cholesterol • risks from saturated fats • mostly associated with LDL cholesterol • risks from trans fats • alter blood cholesterol the same way saturated fats do • dietary cholesterol • implicated in raising blood cholesterol

30. Health Benefits • monounsaturated and polyunsaturated fats • lower possibility of heart disease • Omega-3 fats • protects against blood clots, irregular heart beats and lowers blood pressure

31. Obesity • fat contributes more than 2X the kcalories/gram as carbs or proteins

32. Recommended Intakes • no RDA or upper limits on fat intake has been set • suggest a diet low in saturated fat, trans fat, cholesterol • provides 20-35 % of energy • Daily Values have been place on food labels using 30% as guideline

33. Groceries • fats and protein in animal foods • fats and carbohydrates in plant foods • vitamins A, D, E, K go hand in hand with fat • flavor, texture, palatability • meat • trim the fat • use soy protein instead of animal protein

34. Groceries • milk and milk products • fat free and low fat milk provides the same or more protein, calcium as whole milk • fermented milk products may lower blood cholesterol • veggies, fruits, grains • lower the content of saturated fat, cholesterol, and total fat • fill up on these little or no fat foods

35. Groceries • invisible fat • marbling in steak, cheese, fried foods, baked goods, chocolate

36. Choose Wisely

37. Fat Replacers • fat replacers • carbs or proteins that replace some of the function of fat • still contribute some energy during digestion

38. Artificial Fats • chemically produced substances made to mimic the sensory and cooking attributes of fat • resistant to digestion • olestra • passes through the system unabsorbed • binds to some vitamins • food needs to be fortified • FDA approved

39. Butter and Margarine Labels Compared Margarine (liquid) Margarine (tub) Margarine (stick) Butter INGREDIENTS: Liquid soybean oil, water, sweet cream buttermilk, salt, partially hydrogenated cottonseed oil, vegetable mono- and diglycerides, soy lecithin, citric acid, artificial flavor, vitamin A, colored with beta carotene. INGREDIENTS: Water, liquid soybean oil, partially hydrogenated soybean oil, sweet cream, buttermilk, gelatin, salt, vegetable mono- and diglycerides, soy lecithin, lactic acid, artificial flavor, vitamin A, colored with beta INGREDIENTS: Vegetable oil blend (partially hydrogen- ated and liquid soybean oils) water, sweet cream butter- milk, salt, vegetable mono- and diglycerides, soy lecithin, citric acid, artificial flavor, vitamin A, colored with beta carotene. INGREDIENTS: Cream, salt.