1. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Lipids

2. What Are Fats? Fats are one type of lipid. Lipids: diverse class of molecules that are insoluble in water. Lipids (fats) do not dissolve in water.

3. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings What Are Fats? Three types of lipids are found in foods: (1) Triglycerides (2) Phospholipids (3) Sterols

4. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Triglycerides Triglycerides are composed of Three fatty acid molecules Fatty acids are long chains of carbon atoms surrounded by hydrogen atoms One glycerol molecule Glycerol is a 3-carbon alcohol that is the backbone of a triglyceride

5. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Triglycerides

6. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Triglycerides Fatty acids can differ in Length of their carbon chain Short-, medium-, or long-chain Level of saturation Saturation refers to how many hydrogen atoms surround each carbon Shape

7. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Names of some common Fatty Acids Lipid # Carbons # double bonds # omega Lauric Acid 120none Myristic Acid 140none Palmitic Acid 160none Stearic Acid 180none Oleic Acid 181omega-9 Linoleic Acid 182omega-6 Conjugated Linoleic Acid 182omega-6 Alpha-Linoleic Acid 183omega-3 Gamma-Linoleic Acid 183omega-6 Di-homo-Gamma-Linoleic Acid 203omega-6 Arachidonic Acid 224omega-6

8. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Triglycerides Saturated fatty acids have a hydrocarbon tail that consists of single-bonded carbons only. Monounsaturated fatty acids contain one double bond in the hydrocarbon tail. Polyunsaturated fatty acids contain multiple double in the hydrocarbon tail.

9. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Triglycerides

10. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Triglycerides The shape of a triglyceride is determined by the saturation of the carbon chains. Saturated fatty acids can pack tightly together and are solid at room temperature. For example animal fats, butter, and lard are high in saturated fatty acids.

11. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Triglycerides Unsaturated fatty acids do not stack together well and are liquid at room temperature. Plant oils have unsaturated fatty acids. The hydrogen atoms at the unsaturated region can be arranged in different positions: Cis – same side of the carbon chain Trans – opposite sides of the chain

12. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Triglycerides

13. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Triglycerides Hydrogenation: The addition of hydrogen atoms to unsaturated fatty acids. Coverts liquid fats (oils) into a more solid form Used to create margarine from plant oil Often creates trans fatty acids

14. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Phospholipids Are composed of Glycerol backbone 2 fatty acids Phosphate Are soluble in water Are manufactured in our bodies so they are not required in our diet

15. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Phospholipids

16. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Sterols Sterols: Lipids containing multiple rings of carbon atoms. Are essential components of cell membranes and many hormones Are manufactured in our bodies and therefore are not essential components of our diet

17. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Sterols

18. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Digestion of Fats Fats are not digested and absorbed easily because they are insoluble in water. Very little digestion of fats occurs in the watery environments of the stomach and mouth. Most digestion of fats begins in the small intestine.

19. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Digestion of Fats

20. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 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

21. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 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

22. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Structure of a Lipoprotein

23. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 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.

24. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings 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

25. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Role of Fat Energy Fat is very energy dense, containing 9 kcal per gram. Much of the energy used during rest comes from fat. Fat is used for energy during exercise, especially after glycogen is depleted. Fat is also used for energy storage.

26. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Role of Fat Essential fatty acids Two fatty acids cannot be synthesized in the body and must be obtained in the diet: (1) Alpha-linoleic acid (omega-3 fatty acid) Found in vegetables, fish and fish oils (2) Linoleic acid (omega-6 fatty acid) Found in vegetable and nut oils

27. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings What foods are rich in Omega-3?

28. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Essential Fatty Acids “Essential for well-being”: Lowers the risk of breast and colon cancer Improve learning and attention span in school- children Improve cognitive function in the elderly Elevate mood, resulting in less depression Lower the risk of cardiovascular disease Promote healthy skin Improve vision, especially night vision

29. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Role of Fat Fat-soluble vitamins Vitamins A, D, E, and K are soluble in fat; fat is required for their transport Fat is essential to many body functions Cell membrane structure Nerve cell transmissions Protection of internal organs Insulation to retain body heat

30. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Role of Fats Fat provides flavor and texture to foods. Fat contributes to making us feel satiated because Fats are more energy dense than carbohydrates or protein Fats take longer to digest

31. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings How Much Fat? The Acceptable Macronutrient Distribution Range (AMDR) for fat: 20-35% of calories should be from fat Athletes and highly active people may need more energy from carbohydrates and can reduce their fat intake to 20-25% of total calories.

32. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings How Much Fat? The type of fat consumed is important. Saturated fat should be no more than 7% of total calories. Trans fatty acids should be reduced to the absolute minimum. Most fat in our diets should be from monounsaturated fats (eg., olive oil).

33. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Food Sources of Fat Visible fats Fats we knowingly add to foods Butter, cream, mayonnaise, dressings Invisible fats Fats hidden in foods Naturally occurring or added during processing

34. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Health Problems From Fat Cardiovascular disease Dysfunction of the heart or blood vessels Can result in heart attack or stroke The type of fat in our diet can contribute to or protect against cardiovascular disease.

35. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cardiovascular Disease Risk factors for cardiovascular disease include Being overweight Physical inactivity Smoking High blood pressure Diabetes

36. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cardiovascular Disease Blood lipids include Chylomicrons VLDLs – very low-density lipoproteins LDLs – low-density lipoproteins “bad cholesterol” HDLs – high-density lipoproteins “good cholesterol”

37. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Types of Blood Lipids

38. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cardiovascular Disease Diets high in saturated fats Decrease the removal of LDLs from the blood Contribute to the formation of plaques that can block arteries Increase triglyceride levels (chylomicrons and VLDLs)

39. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cardiovascular Disease Cross-section of (a) a normal artery and (b) a partially blocked artery.

40. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cardiovascular Disease Trans fatty acids: Can raise blood cholesterol levels as much as saturated fat Are abundant in hydrogenated vegetable oils (margarine, vegetable oil spreads) Should be reduced to the absolute minimum

41. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cardiovascular Disease How can fat intake protect against heart disease? Diets high in omega-3 fatty acids (along with moderate exercise) can increase HDL “good” cholesterol levels.

42. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings What are “fat-replacers”?

43. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings What are “fat replacers”?

44. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings What are “fat replacers”?