LIPIDS Guiding Questions: What is the good, the bad, and the ugly of fats on human health Should you buy fat free products? What type of oils should you cook with?
USES OF LIPIDS IN THE BODY
Lipids are stored in adipose tissue Born with them. They just grow bigger or smaller. Can be removed with liposuction Lipids are stored in adipose tissue
Structure
Fatty acids can be saturated or unsaturated
Properties of Fatty Acids Chain Length (number of carbons linked together) Shorter = more soluble in water Saturated (maximum number of hydrogens) C. Unsaturated = one (mono) or more (poly) is missing (double or triple bonds)
TRANS FATTY ACIDS Hydrogenated fats– 1. 2. Effects stability and protects against oxidation; more “shelf- stable” 3. Widely used by food industry in margarine, shortening, peanut butter, baked goods & snack food
Essential Fatty Acids 1. Linoleic – omega-6 fatty acid and Linolenic – omega-3 fatty acid 2. Play a role in normal growth & development and may prevent heart disease, hypertension, arthritis & cancer
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Copyright 2005 Wadsworth Group, a division of Thomson Learning Which oil to use?
Cholesterol – a Sterol Found only in animal products Structure of cell membranes Used to make bile for digestion
Fat Digestion Hydrolysis Triglycerides Copyright 2005 Wadsworth Group, a division of Thomson Learning
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Emulsification of Fat by Bile Copyright 2005 Wadsworth Group, a division of Thomson Learning
Size & Compositions of Lipoproteins
Health Effects of Lipids Benefits from monounsaturated fats and polyunsaturated fats May help neural activity Provides energy Benefits from omega-6 and omega-3 fats 1. May reduce blood cholesterol & help prevent cancer Copyright 2005 Wadsworth Group, a division of Thomson Learning
Dietary Recommendations 1. Limit total fat intake to <30% of kcals Example: If 2000 kcal diet, then 2000 x .30 = 600 kcals/9 kcals per gram = 65 gms of protein 2. Limit cholesterol to <300 mg/day 3. Saturated & polyunsaturated fats each <10% of kcals Dietary Recommendations
Dietary Recommendations 1. Use all fats in moderation *1 tsp fat = 5 gm = 45 kcals 2. Beware of “hidden fats” – added to convenience foods, processed foods, & in cooking 3. Choose lean meats, skinless poultry, nonfat dairy products; limit meats to <7 oz./day 4. Choose fish 2-3 times/week 5. Choose monounsaturated fats – canola, olive, peanut, or sesame oils; avoid hydrogenated oils 6. Limit egg yolks to 3-4/week Dietary Recommendations
Fat Substitutes Z-Trim; made from plant fibers Types: 1. Carbohydrate based – i.e. Oatrim & Z-Trim; made from plant fibers 2. Protein based – i.e. Simplesse; made from egg white or milk protein 3. Fat based – i.e. Olestra; made from sucrose & fatty acids; passes through body undigested
Fat Substitutes Do they work? 1. Potential health benefits – promote weight loss and lower blood lipids 2. But like sugar substitutes, many people just eat more instead of replacing fat 3. Side effects possible with Olestra 4. Use in moderation