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Chapter Four The Lipids: Fats & Oils

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1 Chapter Four The Lipids: Fats & Oils
NUT SCI 242 Food & Nutritional Health © Karen Lacey, MS ,RD, CD

2 What are Lipids? A family of compounds that includes
Triglycerides (fats & oils) Fats: lipids that are solid at room temperature Oils: lipids that are liquid at room temperature Phospholipids Sterols (cholesterol).


4 I. A Primer on Fats The Functions of Fat in the Body
Energy source esp. for muscles Serves as an energy reserve 1# body fat contains 3500 kcal 30-50# of stored fat

5 Cont’d Major component of cell membranes Nourishes skin & hair
Insulates the body from temperature extremes Cushion the vital organs to protect them from shock



8 B. The Functions of Fat in Food
Provide calories (9 per gram) Provide satiety Carry fat-soluble vitamins & essential fatty acids Contribute aroma & flavor


10 Lipid Terminology Triglycerides: the major class of dietary lipids, including fats & oils Made up of 3 units known as fatty acids and 1 unit called glycerol (backbone) Comprise about 95% of lipids in food and the human body



13 Cont’d Phospholipids: Sterols 2nd of three main classes of lipids
similar to a triglyceride, but contains phosphorous Sterols 3rd of three main classes of lipids; Cholesterol one of the sterols manufactured in the body for a variety of purposes

14 Cont’d Fatty acids: basic units of fat composed of chains of carbon atoms an acid group at one end and hydrogen atoms attached all along their length


16 II. A Closer View of Fats Chain Length (number of carbons linked together) Shorter = more soluble in water Saturated vs. Unsaturated (number of hydrogens the chain is holding) Maximum = saturated Unsaturated = one or more is missing Point of unsaturation = site where hydrogen is missing


18 Cont’d Saturated fatty acid: a fatty acid carrying the maximum possible number of hydrogen atoms Animal foods such as meat, poultry and full-fat dairy products Tropical oils such as palm and coconut


20 Cont’d Unsaturated fatty acid: a fatty acid with one or more points of unsaturation. Found in foods from both plants & animal sources Monounsaturated fatty acids (one double bond) Polyunsaturated fatty acids (two or more)


22 Cont’d Monounsaturated fatty acid: also called a MUFA; a fatty acid containing one point of unsaturation Found mostly in vegetable oils such as olive, canola & peanut

23 Cont’d Polyunsaturated fatty acids: also called a PUFA; a fatty acid in which two or more point of unsaturation occur Found in nuts, vegetable oils such as safflower, sunflower and soybean, and in fatty fish

24 B. Essential Fatty Acids
The body can synthesize all of the fatty acids it needs from carbohydrates, fat or protein except for two: Linoleic acid Linolenic acid PUFAs Found in plant & fish oils


26 Omega - 6 versus Omega - 3 Omega – 6 Linoleic Omega – 3 Linolenic
Cold water fish Help dissolve blood clots Lower blood pressure Dilate the arteries


28 Characteristics of Fats in Foods
Liquid vs Solid More saturated a fat is, the more solid it is at room temperature More unsaturated a fat is, the more liquid it is at room temperature


30 III. Characteristics of Fats in Foods
Hydrogenation The process of adding hydrogen to unsaturated fat to make it more solid and more resistant to chemical changes such as spoiling Increasing a fat’s saturation can cause a fat to lose its unsaturated health benefits


32 C. Trans-Fatty Acids Formed when margarine is processed
Hydrogen molecules are on opposite sides of point of unsaturation “Partially hydrogenated vegetable oil” Link between trans fatty acids and heart disease Table 4-3, page 107 Keep to minimum



35 V. Phospholipids A lipid consisting of a water-soluble head and a fat-soluble tail Contain phosphorous Component of cell membranes Serve as emulsifiers (allow fats and water to mix and travel in and out of cells into watery fluid on both sides)


37 Cont’d Lecithin is a common phospholipid
Often used as an emulsifier in foods such as margarine, chocolate & salad dressings

38 V. Cholesterol – a Sterol
Found only in animal products Also made & used in the body: Structure of cell membranes Used to make bile for digestion Bile: a mixture of compounds, made by the liver, stored in the gallbladder, & secreted into the small intestine Emulsifies lipids to prepare them for enzymatic digestion & helps transport them into the intestinal wall cells

39 Cont’d Used to make the sex hormones estrogen & testosterone
Made into vitamin D with the help of sunlight Deposited in the artery walls leading to plaque buildup & heart disease



42 VI. How the Body Handles Fat
Digestion Emulsification Absorption









51 VII. Lipids & Health Good vs. Bad Cholesterol



54 B. Lowering Blood Cholesterol Levels
Eat no more than 30% of calories from fat Eat no more than 8-10% of calories from saturated fat Eat no more than 10% of calories from PUFAs MUFAs should make up 10-15% of total calories Limit daily cholesterol intake to no more than 300 milligrams

55 VIII. Fat in the Diet Food Guide Pyramid
3 groups traditionally account for nine-tenths of the fat in the U.S. diet Fats, oils & sweets group Meat, poultry, fish, dry beans, eggs & nut group Milk, yogurt & cheese group Most of the fat in our diets comes from animal products


57 B. Fat Substitutes Carbohydrate-based Protein-based
Help retain moisture to maintain the juiciness or creaminess that is lost with fat reduction Carrageenan, fruit purees, gelatin, gums, starches & products made from fiber Protein-based Proteins are cooked & blended to form tiny round particles that trap water to maintain the mouth feel of fat Whey protein concentrate (Dairy-Lo), or milk & egg white protein (Simplesse)

58 Cont’d Fat-based Are either only partially digestible or completely undigestible to prevent absorption of fat Caprenin (substitute for cocoa butter in candy), Salatrim (found in low fat baking chips), and olestra (often found in fat free potato chips)

59 C. At the Grocery Store Read labels to determine both the amounts & types of fat contained in foods


61 D. In the Kitchen Use canola & olive oil for baking & cooking
Prepare lean cuts of meat Bake, broil & steam instead of frying Use low-fat or fat-free dairy products & dressings Season with herbs & spices rather than with fats Incorporate plant-based protein sources such as soy & legumes

62 E. At the Table Eat more fresh fruits & vegetables
Use jam instead of butter Limit use of high-fat condiments including mayo, butter & sour cream or use low-fat varieties Use mostly monounsaturated vegetable oils such as olive or canola Eat fewer high-fat desserts

63 F. Recipe Modification Egg whites Fat-free evaporated milk
Fat-free sour cream Fruit purees Fat-free cream cheese Oils

64 IX. Diet & Heart Disease Risk Factors High cholesterol
High blood pressure Smoking Diabetes Lack of exercise Stress Obesity Unhealthy diet Age Gender Genetics

65 Cont’d Ways to Reduce Risk Limit intake of cholesterol & saturated fat
Quit smoking Maintain a healthy weight Eat high fiber foods Increase physical activity Increase fruit & vegetable consumption Limit alcohol consumption

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