Fats and Other Lipids Chapter 6 Fats and

Fats and Other Lipids Chapter 6: Fats and other Lipids 1

6. 1 Understanding Lipids • Lipids include: 1. 2. 3. 4. Fatty acids Triglycerides Phospholipids Cholesterol “Oil and Water Don’t Mix” Because oil is less dense than water, it floats on top. • Lipids are • insoluble in water • less dense than water Chapter 6: Fats and other Lipids 2

1. Fatty Acids • Fatty acids contain a hydrocarbon chain (carbon and hydrogen atoms) with a methyl group (CH 3) at one end an acid group (COOH) at the other. • Fatty acids vary in their number of carbons: Chapter 6: Fats and other Lipids • Short chain fatty acids — 2 to 4 carbons • Medium chain fatty acids — 6 to 12 carbons • Long chain fatty acids — 14 to 24 carbons 3

Saturation • Fatty acids also vary by saturation. • Saturated – each carbon atom within the chain holds 2 hydrogen atoms. • Unsaturated – one or more carbon atoms within the chain lack 2 hydrogen atoms, and as a result, the molecule has 1 or more double bonds. Chapter 6: Fats and other Lipids 4

Essential Fatty Acids “Essential”- you must have them in your diet but your body can’t make them! Chapter 6: Fats and other Lipids 5

Essential Fatty Acids • Precursors of prostaglandins – Hormone-like substances formed from EPA, DHA, and arachidonic acid • (green ovals from previous slide) • Effects of prostaglandins: – Stimulate uterine contractions – Regulate blood pressure – Promote immune system response Chapter 6: Fats and other Lipids 6

Trans Fats • What are trans fats? – Unsaturated fats with at least 1 trans double bond rather than the more common cis double bond – *Fatty acids!* • Hydrogenation: – Process that adds hydrogen atoms to liquid vegetable oils to make trans fats • Partial hydrogenation: – Not all double bonds are hydrogenated. – Natural cis double bonds convert to the unhealthy trans form. – Has a longer shelf-life Chapter 6: Fats and other Lipids 7

Trans Fats and Health • Used in many processed foods – High amounts of trans fats in diet increase heart disease risk by raising blood cholesterol levels. – FDA requires amount of trans fat displayed on Nutrition Facts panel. Chapter 6: Fats and other Lipids 8

Approximate Percentages of Saturated and Unsaturated Fatty Acids in Common Fats and Oils Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. % Monounsaturated % Saturated Safflower oil 6. 5 Sunflower oil 15. 1 78. 4 10. 8 20. 4 Soybean oil 16. 3 Corn oil % Polyunsaturated 68. 8 23. 7 13. 6 29. 0 Cottonseed oil 27. 1 Peanut oil 60. 0 57. 4 18. 6 54. 3 17. 7 Canola oil 48. 6 7. 5 33. 7 64. 0 Margarine (80% fat, partially hardened corn and soybean oils) 19. 0 28. 5 50. 0 31. 2 Chicken fat 46. 8 21. 9 41. 0 Lard (pork fat) 47. 2 14. 2 Olive oil 11. 7 75. 0 Palm oil 51. 6 Beef fat 52. 1 10. 8 38. 7 43. 7 65. 6 Butter 34. 4 3. 0 92. 0 Coconut oil 0 10 20 30 40 50 60 Approximate Chapter 6: Fats and other Lipids Percentages 70 80 (Values for each fat/oil may not total 100% because of rounding) © The Mc. Graw-Hill Companies, Inc. /Elite Images, photographer; 4. 2 30. 5 4. 0 62. 4 Cocoa butter 9. 7 90 6. 0 2 100 9

2. Triglycerides • Composed of 3 fatty acids attached to a glycerol “backbone” • ~ 95% of lipids in the body and foods is in the form of triglycerides. Chapter 6: Fats and other Lipids 10

3. Phospholipids • Chemically similar to a triglyceride, 1 fatty acid is replaced • by a compound containing phosphorus and nitrogen groups • Lecithin - main phospholipid in foods, such as egg yolks, liver, wheat germ, peanut butter, and soy • Phospholipids act as emulsifiers, because they have hydrophobic and hydrophilic regions. – Hydrophobic region • Attracts lipids and avoids water – Hydrophilic region • Attracts water and avoids lipids Chapter 6: Fats and other Lipids 11

4. Cholesterol • Cholesterol is a sterol, a compound that is more complex than most other lipids. It is essential to our diet & only found in animal foods. • The body uses cholesterol to make various substances, including: – Vitamin D – Steroid hormones • Estrogen • Testosterone – Bile Chapter 6: Fats and other Lipids 12

6. 2 What happens to lipids in your body? • Lingual lipase in the mouth is activated in the acidic stomach and small amounts of digestion can occur in the stomach. • In the duodenum, pancreatic lipase digests triglycerides, forming primarily: – Monoglycerides – Free fatty acids Chapter 6: Fats and other Lipids 13

Gallbladder • Bile - made in the liver and stored in the gallbladder • Bile contains bile salts that aid in lipid digestion. • Without bile, lipids clump together in large fat globules Chapter 6: Fats and other Lipids 14

Lipid Digestion and Absorption Chapter 6: Fats and other Lipids 15

Journey Into the General Circulation • Chylomicrons are transported from the SI through the lacteals in the lymphatic system • Lymph vessels eventually return this into general circulation via the subclavian vein Chapter 6: Fats and other Lipids 16

Summary of lipid digestion and absorption Chapter 6: Fats and other Lipids 17

Recycling Bile Salts • Enterohepatic Circulation – After bile salts are used to aid lipid digestion, the salts are absorbed in the ileum and return to liver for the production of new bile. • Soluble fibers and plant sterols/stanols interfere with bile and cholesterol absorption. Note: Some synthetic margarine spreads contain plant sterols or stanols. Chapter 6: Fats and other Lipids 18

Adipose Cells • Adipose cells store triglycerides as fat droplets. • Adipose cells can break down triglycerides into fatty acid and glycerol molecules before releasing them into blood stream. – Liver can convert glycerol to glucose—another energy source. • Triglycerides provide 9 kcal/g (carbohydrate & protein provide 4 kcal/g) Chapter 6: Fats and other Lipids 19

Lipid Consumption Patterns • Do Americans eat more or less fat than 100 years ago? – 1987 to 1988 approx. 54 lbs/year/person – 2007 to 2008 63 lbs/year/person • Fat contributes ~34% of the average American’s daily caloric intake. • Acceptable Macronutrient Distribution Range 20 to 35% of total calories • U. S. Dietary Guidelines 2010 – < 10% of calories from saturated fats – < 300 mg cholesterol daily – trans fatty acid intake as low as possible 20 Chapter 6: Fats and other Lipids

Understanding Nutritional Labeling: Lipids • Lipid information required on Nutrition Facts panel: – – – Total kilocalories from fat Total fat (g) Saturated fat (g) Trans fat (g) Cholesterol (mg) • Panel may include: – Polyunsaturated (g) – Monounsaturated (g) Chapter 6: Fats and other Lipids 21

Why “Grams of Fat” May Not Add Up Label states: Total Fat 2 g Saturated Fat Trans Fat Poly. Fat Mono. Fat ? 0 g 0 g 1 g* * If a food has < 0. 5 g of a specific fat it can be labeled as having “ 0 g. ” Chapter 6: Fats and other Lipids 22

Lipids and Health: Cardiovascular Disease (CVD) • CVD: diseases of the heart and blood vessels • Most common forms of CVD are: • Heart disease (“coronary artery disease”) • Stroke • 1 in 3 adult Americans have some form of CVD. – Responsible for ~30% of deaths in the U. S. in 2009 Chapter 6: Fats and other Lipids 23

From Atherosclerosis to Cardiovascular Disease • Atherosclerosis — disease in which lipid-containing plaques build up inside arteries • Plaque forms in an artery when something irritates the lining of the artery wall. • Plaque narrows arteries, interfering with circulation. • Plaque may also result in the formation of a fixed clot— a thrombus. Chapter 6: Fats and other Lipids 24

Healthy artery vs. Atherosclerotic artery • Note differences between the cross sections of the two arteries. The one artery is almost blocked completely from atherosclerosis Chapter 6: Fats and other Lipids 25

Embolus Formation • A thrombus that breaks away and travels through the blood is an embolus. – If an embolus lodges in the heart, it can cause a heart attack (myocardial infarction). – If an embolus lodges in the brain and deprives brain cells of oxygen and nutrients, a stroke results. Chapter 6: Fats and other Lipids 26

Arteriosclerosis • What is Arteriosclerosis? – Condition that results from atherosclerosis – Characterized by loss of arterial flexibility – Commonly referred to as “hardening of the arteries” – Contributes to hypertension • What is Hypertension? – Chronic condition characterized by abnormally high blood pressure levels – May cause these hardened arteries to tear or burst Chapter 6: Fats and other Lipids 27

Major Risk Factors for CVD Chapter 6: Fats and other Lipids 28

Genetics and CVD • Genetics (family history) cannot be modified. – Genes may: • code for physical conditions that increase risk hypertension and diabetes. • influence way circulatory and immune systems respond to diet. • Someday genetic testing may be available to determine markers for CVD. Chapter 6: Fats and other Lipids 29

Modifiable Risk Factors • • • Smoking Hypertension* Diabetes* Excess body fat* Elevated blood cholesterol (LDL)* Physical inactivity *Influenced by diet Chapter 6: Fats and other Lipids 30

Lipoproteins and Atherosclerosis • Lipoproteins: – Transport lipids in the blood – Play major role in atherosclerosis development – Carry different types of lipids and can influence plaque formation differently – 3 types of lipoproteins: 1. High density lipoproteins – HDL 2. Low density lipoproteins – LDL 3. Very Low density lipoproteins – VLDL Chapter 6: Fats and other Lipids 31

Lipoproteins HDL • commonly called “good” cholesterol • Transports cholesterol away from tissues and to the liver where it can be eliminated LDL VLDL • commonly called • May contribute to “bad” cholesterol atherosclerosis • Conveys cholesterol • Primarily carries to tissue. triglycerides • May become oxidized LDL & contribute to atherosclerotic plaque Chapter 6: Fats and other Lipids 32

Roles of HDL, LDL, and Oxidized LDL Chapter 6: Fats and other Lipids 33

Assessing Your Risk of Atherosclerosis • Lipid (Lipoprotein) Profile – Blood test that determines total cholesterol, HDL & LDL cholesterol, and triglyceride levels • Desirable levels: – – Total Cholesterol LDL Cholesterol HDL Cholesterol Triglycerides < 200 mg/dl < 100 mg/dl 40 -60 mg/dl* < 150 mg/dl • * 40 -60 for men, 50 -60 for women Chapter 6: Fats and other Lipids 34

C-reactive Protein • High-sensitivity Creactive protein – (hs-CRP) – Protein produced primarily by liver in response to inflammation • This protein is a marker for CVD and hypertension – Note: A “marker” is an early physiological warning sign that can be measured. Chapter 6: Fats and other Lipids 35

Coronary Calcium • Coronary calcium consists of specks of calcium (tiny calcifications) in arteries of the heart. • Associated with: smoking and elevated total cholesterol. Chapter 6: Fats and other Lipids 36

Reducing Your Risk of Atherosclerosis: Dietary Changes • Impact of dietary fat & cholesterol on blood lipids: – Saturated fats increase LDL and HDL – Trans fats increase LDL but lower HDL – Cholesterol increases LDL – Monounsaturated fats lower LDL but not HDL – Polyunsaturated fats lower LDL and lower HDL in some people. Chapter 6: Fats and other Lipids 37

Dietary Recommendations ü Limit: - Saturated fats to <10% of total kcal - Trans fats limited to as little as possible ü Choose unsaturated fats to replace saturated and trans fats. Chapter 6: Fats and other Lipids 38

Omega-3 and Omega-6 Fatty Acids Omega-3 • Sources: Fatty fish, canola oil, walnuts, and flaxseed • Actions: Reduces inflammation, blood clotting, and blood pressure • May reduce risk of heart disease Omega-6 • Sources: Animal fats and vegetable oils • Actions: Increases inflammation and blood clotting • May also reduce risk of heart disease Chapter 6: Fats and other Lipids 39

Rich Food Sources of Omega-3 Fatty Acids Chapter 6: Fats and other Lipids 40

Common Questions About Fats Should You Avoid Eggs? • Dietary sources of cholesterol, such as eggs, does not increase blood cholesterol levels as much as dietary sources of saturated fat. Is It Safe to Eat Butter? • “Stick” margarine may be more harmful to health, because it contains cholesterol-raising trans fat. Liquid or soft margarines may be less harmful. Will Weight Loss and Exercise Help? • Achieving a healthy body weight often reduces CVD risk. Excess abdominal fat is associated with elevated LDL Chapter 6: Fats and other Lipids levels. 41

Ways to Lower Your Risk of CVD Chapter 6: Fats and other Lipids 42

Food Selection and Preparation Strategies to reduce dietary fat include: üReduce intake of fried foods. üPurchase lean cuts of meat and trim visible fat. üReplace some fatty foods with reduced-fat or fat-free alternatives. üReplace high-fat sandwich meats with nut butters. üChoose low-fat snack foods. üUse less salad dressing on salads. Chapter 6: Fats and other Lipids 43

Fat Replacers Synthetic fat replacers were developed to meet consumer requests for lower fat foods. üOatrim üSimplesse üOlean Chapter 6: Fats and other Lipids 44

Other Dietary Modifications • Increase soluble fiber intake • Reduce intake of refined carbohydrates • Monitor alcohol intake – A small amount can raise HDL but increase blood triglyceride levels and blood pressure • Lose excess body fat • Follow the Mediterranean Diet Pyramid Chapter 6: Fats and other Lipids 45

Chapter 6: Fats and other Lipids Mediterranean Diet Pyramid 46

What If Lifestyle Changes Don’t Work? People who cannot lower blood cholesterol levels after lifestyle modifications may need prescription drugs such as: Statins — class of medications that interfere with liver’s metabolism of cholesterol “Zetia©” — inhibits intestinal absorption of cholesterol Chapter 6: Fats and other Lipids 47