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Chap. 5: Lipids

Chap. 5: Lipids. FAT FACTS. Lipids or “Fats” are essential to good health Fat is found in almost all foods Recommended intake of dietary fat: 20%-35% of kcal. 3,500 kcal = 1 lb. of fat. Properties of Lipids. Do not readily dissolve in water Fats are solid at room temperature

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Chap. 5: Lipids

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  1. Chap. 5: Lipids

  2. FAT FACTS • Lipids or “Fats” are essential to good health • Fat is found in almost all foods • Recommended intake of dietary fat: 20%-35% of kcal. • 3,500 kcal = 1 lb. of fat

  3. Properties of Lipids • Do not readily dissolve in water • Fats are solid at room temperature • Oils are liquid at room temperature • Triglycerides are the main form of lipids in food and body (storage) • Energy dense (9 kcal /gm)

  4. Functions of Somatic Fat • Stored Energy Reserve • Insulation • Cushioning • Transport fat-soluble vitamins • Forms Cell Membranes (cholesterol)

  5. Functions of Dietary Lipids • Concentrated source of energy (kcal) • Satiety (slows emptying of stomach) • Aroma, Flavor and mouth feel

  6. Requirements for Dietary Lipids • 20% to 35% of total caloric intake. • This is approximately 44 to 77 grams of fat if you consume 2000 kcal per day. • Less than 10% of the daily kcal intake should be from saturated fat. • This is approximately 22 grams of saturated fat if you consume 2000 kcal/day. • A large percentage of fat intake should come from monounsaturated oils.

  7. Sources of Dietary Lipids

  8. Bacon Double Cheeseburger or Tender Crisp Chicken Sandwich? ﻌ Croissant or Chocolate Eclair? ﻌ 6” Cold Cut Combo Or 6” Tuna Sub

  9. Bacon Double Cheeseburger (32g) or Tender Crisp Chicken Sandwich? (43) ﻌ Croissant (25g) or Chocolate Eclair? (11g) ﻌ 6” Cold Cut Combo (21g) Or 6” Tuna Sub (31g)

  10. Types of Fat • Triglycerides • Make up 95% of all fats • Composed of a water soluble glycerol and three water insoluble fatty acids • Phospholipids • Composed of glycerol, 2 fatty acids and a phosphorus. • Primary function is to emulsify fats. • Sterols • Compounds composed of several carbon rings that has several biological functions

  11. Triglycerides • The most common type of fat found in the body (95% of all fats are triglycerides)

  12. Triglycerides H H--C--OH H--C--OH H--C--OH H Fatty Acid Fatty Acid Fatty Acid H O H--C--O--C-- O H--C--O--C-- O H--C--O--C-- H Fatty Acid + Fatty Acid Fatty Acid Condensation

  13. Three Types of Fatty Acids • Saturated fatty acids are solid at room temperature. Should be consumed sparingly in diet. • Monounsaturated Fats are liquid at room temperature. Consumption does not have to be limited. • Polyunsaturated Fats are liquid at room temperature. Should be consumed moderately.

  14. omega end alpha end Note: All carbons connected by single bonds Saturated Fatty Acid Structure (Fig. 5-1-A) H H H H H H H H H H H H H H H H H O H-C--C--C--C--C--C--C--C--C--C--C--C--C--C--C--C--C-C-OH H H H H H H H H H H H H H H H H H

  15. omega end alpha end Note: Only ONE double bond Monounsaturated Fatty Acid Structure (Fig. 5-1-B) H H H H H H H H H H H H H H H O H-C--C--C--C--C--C--C--C--C=C--C--C--C--C--C--C--C--C-OH H H H H H H H H H H H H H H H H H

  16. omega end alpha end > 2 double bonds Polyunsaturated Fatty Acid Structure (Fig. 5-1-C) H H H H H H H H H H H H H O H-C--C--C--C--C--C=C--C--C=C--C--C--C--C--C--C--C--C-OH H H H H H H H H H H H H H H H H H

  17. Triglycerides can contain a mixture of saturated, monounsaturated and polyunsaturated fatty acids.Most of our dietary lipids are mixed triglycerides.

  18. Oxidation • Oxidation: The removal of electron(s) from atoms of a compound or element by oxygen or another ion/atom. • Alters appearance or function of compound or element • EX: Rust on iron

  19. Fat Oxidation Concerns • Fatty acid oxidation in the body increases free radical production which destroys cells • Fatty acid oxidation in the body damages arterial walls and increases CVD risk • Fatty acid oxidation in foods is not harmful, but is unpleasant to taste and smell. Oil that is oxidized is called “rancid.”

  20. Hydrogenation of Fatty Acids • Process used to solidify an oil and slow oxidation. • Addition of H to C=C double bonds • Increases shelf life • Formation of trans fatty acid (similar to shape of saturated fatty acid)

  21. Cis and Trans Fatty Acid

  22. Health Dangers of Excessive Trans Fatty Acids • Raises LDL • Lowers HDL • Increases risk for heart disease • Damages artery walls

  23. Minimize Intake of Trans Fatty Acid • Limit use of solid oils (margarine) • Limit deep-fried foods • Limit high fat baked goods • Limit use of all processed foods

  24. Essential Fatty Acids • Needed for production of hormone-like compounds called eicosanoids which regulate inflammation, clotting, immune function, vision, and allergic response.

  25. Essential Fatty Acids Omega 6Omega-3 Linoleic acid Alpha-linolenic acid (corn, soybeans, nuts, seeds, greens) (canola oil, walnuts, flaxseed) Gamma-Linolenic acid DHA (borage oil, primrose oil) (docosahexanoic acid) Fish oil Arachidonic Acid EPA (meat)(eicosapentaenoic acid) Fish oil

  26. The Different Effects • Omega-6 • increases blood clotting • increases inflammatory responses • promotes activation of leukocytes • Omega-3 • reduces heart attack • Inhibits inflammation • Inhibits cancer growth • decreases blood clotting • excess may cause hemorrhagic stroke Ratio of Omega 6: Omega 3 4:1

  27. omega end alpha end 1st double bond is located on the 6th carbon from the omega end Essential Fatty Acid- Omega-6 (alpha-linoleic acid) H H H H H H H H H H H H H O H-C--C--C--C-- C--C =C--C--C=C--C--C--C--C--C--C--C--C-OH H H H H H H H H H H H H H H H H H

  28. Omega-6 Fatty Acid • Found in vegetable oils • Only need ~ 1 tablespoon a day • About 14g per day

  29. omega end alpha end 1st double bond is located on the 3rd carbon from the omega end Essential Fatty Acid- Omega-3 (alpha-linolenic acid) H H H H H H H H H H H H H H H H H O H-C--C--C=C--C--C =C--C--C=C--C--C--C--C--C--C--C--C-OH H H H H H H H H H H H

  30. Omega-3 Fatty Acid • EPA and DHA Primarily from fish oil, Omega 3 eggs. • Alpha-Linolenic found in canola oil, soybean oil, flaxseed oil, enriched cereals, and walnuts. • Body can convert ALA to EPA, but conversion to DHA difficult. • Recommend intake of ~2 servings of fish per week or 6-10 oz. • About 2 grams per day.

  31. Phospholipid • Built on a glycerol backbone • Has at least one fatty acid replaced with phosphorus compound • Found in body • Synthesized by the body as needed

  32. Functions of Phospholipids • Make up cell membrane • Emulsifier • Bile acids • Lecithins • Improves food products

  33. Emulsification

  34. Sterols: Cholesterol • Essential component of cell membrane • Produced by the liver • Found only in animal products • Forms important hormones • Estrogen, testosterone, vitamin D • Precursor to bile

  35. Structure of Cholesterol

  36. Dietary Cholesterol • Dietary cholesterol is found only in animal products. Since the liver makes cholesterol, only things with a liver have cholesterol. • Dietary cholesterol serves no purpose since the liver makes all your body needs. • Dietary cholesterol has little affect on blood cholesterol.

  37. LIPID DIGESTION

  38. Carrying Lipids in the Bloodstream • Triglycerides are too large to be transported in the blood. • Unique system of fat transportation is needed called “lipoproteins.” • Lipoproteins are packaged lipids with a protein exterior and are transported to the bloodstream via lymph.

  39. Types of Lipoproteins • Chylomicrons. Largest of the lipoproteins carry mostly triglycerides from the intestines to the rest of the body via lymph. • VLDL. Very low density lipoproteins. Carry mostly chylomicron remnants and lipids assembled by the liver. • LDL. Low density lipoprotein. The remnant of VLDL. Carries mostly cholesterol. Has a propensity to oxidize and damage arteries • HDL. High density lipoprotein. Carries some lipids, but is mostly protein. Retrieves cholesterol from the cells and delivers to the liver for recycling.

  40. Lipoproteins

  41. Dangers of too much fat • Obesity • Diabetes • Hypertension • cancer • Elevated Triglycerides and Cholesterol • Diabetes • Heart disease

  42. Jared is a 42 year old man with heart disease. His doctor says he needs to cut down on saturated fats (less than 10% of kcal), trans fats, and incorporate more monounsaturated and polyunsaturated fats into his diet. In addition, the doctor advises he gets in some Omega 3 fatty acids as well. • If you are the dietitian, what kind of foods would you suggest that Jared eat in order to comply with the doctor’s orders? In addition, if Jared eats 2500 kcal per day, how many grams of saturated fat is he limited to?

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