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The Health Benefits of Fats Quiz Yourself True or False 1. To lose weight, use regular, stick margarine instead of butter because it has 25% fewer kilocalories per teaspoon. T F 2. Egg yolks are a rich source of cholesterol. T F 3. Taking too many fish oil supplements may be harmful to health. T F 4. Increasing your intake of trans fats can reduce your risk of heart disease. T F How Did You Do? 1. False Regular stick margarine has about the same kcal/teaspoon as butter. 2. True Egg yolks are a rich source of cholesterol. 3. True Taking too many fish oil supplements may be harmful to health. 4. False The average American consumes about 1/3 of his/her daily energy intake from fat. 5. False Increasing your intake of trans fats may increase your risk of heart disease. A balanced picture of fats • Is all fat bad for you? Dietary Lipids • Triglycerides—the major form of fat in food • Phospholipids—similar to triglycerides in basic structure; contain phosphate containing groups • Sterols—mainly cholesterol • Fat-soluble vitamins (A, D, E, K) • Some phytochemicals (carotenoids) Triglyceride Properties • Concentrated source of energy (9 kcal/gm) • Source of essential fatty acids • Required for absorption of fat soluble vitamins by acting as a carrier in the small intestine • Increase palatability and satiety value of foods • Protection of organs and insulation Triglyceride Composed of 3 fatty acid molecules bonded to a glycerol molecule • Composed of carbon, hydrogen, oxygen Triglyceride Properties • Contain less oxygen than carbohydrates so they contain more energy • Insoluble in water –Require emulsification by bile acids for adequate digestion Triglycerides: Fatty Acids • Fatty acids are composed of a chain of carbon atoms with a carboxyl (acid) group at one end. • Hydrogen atoms are bonded to the carbons. – Carbon chain length can vary. Fatty Acids: The three types of fatty acids are present in most food fats • Saturated – Animal fats (milk products, butter, meat) – Coconut oil – Palm and palm kernel oils • Monounsaturated – Olive oil – Canola oil – Peanut oil – Safflower oil • Polyunsaturated – Most vegetable oils except palm kernel and coconut oils – Nuts, seeds – Chicken, turkey, fish Saturated Fat • Saturated—no double bonds exist between carbons; only single bonds between carbons – Carbons are fully saturated with hydrogen atoms; only single bonds exist between carbons – Palmitic acid (16 carbons)—the most abundant saturated fatty acid in foods Unsaturated Fatty Acids • Monounsaturated—one double bond in the carbon chain • Polyunsaturated—more than one double bond in the carbon chain • Short chain fatty acids — 2 to 4 carbons • Medium chain fatty acids — 6 to 12 carbons • Long chain fatty acids –- 14 to 24 carbons Saturated fats • Solid at room temperature • • • • Butter Lard Vegetable shortening (Crisco) Coconut oil • Tend to raise blood cholesterol and increase heart disease risk. Can also increase insulin levels. • Lowering dietary fat can lower cholesterol levels. Monounsaturated Fatty Acid • One double bond exists in the carbon chain. • Oleic acid (18 carbons, 1 double bond)—the most abundant monounsaturated fatty acid in foods • Oleic acid is an omega-9 fatty acid because the double bond occurs at the 9th carbon from the omega end of the molecule Monounsaturated Fatty Acids (MUFA): Properties • Liquid at room temperature – Olive oil – Canola oil • Tend to lower blood cholesterol if they replace saturated fat in the diet. Polyunsaturated Fatty Acids (PUFA): Structure More than one double bond exists in the carbon chain Linoleic acid (18 carbons, 2 double bonds) Linoleic acid is an omega-6 fatty acid because the double bond occurs at the 6th carbon from the omega end of the molecule. It’s also known as an n-6 fatty acid. Polyunsaturated Fatty Acids (PUFA): Structure Another important PUFA Linolenic acid (18 carbons, 3 double bonds) •Linolenic acid is an omega-3 fatty acid because the double bond occurs at the 3 carbon from the omega end of the molecule. It’s also known as an n-3 fatty acid rd Polyunsaturated Fatty Acids: Properties • Liquid at room temperature – Most vegetable oils • More chemically unstable – Rancidity occurs more easily • Tend to lower blood cholesterol and reduce heart disease risk. Food Sources of Fatty Acids • Saturated – Animal fats (milk products, butter, meat) – Coconut oil – Palm and palm kernel oils • Monounsaturated – Olive oil – Canola oil – Peanut oil – Safflower oil • Polyunsaturated –Most vegetable oils except palm kernel and coconut oils –Nuts, seeds –Chicken, turkey, fish Essential Fatty Acids • Two essential fatty acids – Linoleic acid (an n-6 fatty acid) – Linolenic acid (an n-3 fatty acid) • They are called essential because they must be consumed to maintain good health. • Both essential fatty acids are polyunsaturated. Essential Fatty Acids—General Functions • Components of cell membranes • Required for growth, reproduction, good skin integrity and wound healing • Precursors of eicosanoids – Eicosanoids are elongated (20C) highly unsaturated fatty acids – Involved with reproductive functioning, immune system integrity, cell growth – Optimize eicosanoids in the body by consuming a balanced ratio of essential fatty acids Linoleic – n-6 Fatty Acid • Unique properties – Can reduce blood cholesterol and heart disease risk – Does not reduce cancer risk • Requirement: Minimum of 3% of total kcal or a total of 60 kcal from linoleic acid. This amount is supplied by 1 tablespoon of soy oil. – Typical American diet provides 7% of kcal as linoleic acid. – Excessive intakes can suppress the immune system . • Good food sources: most vegetable oils, nuts, seeds, poultry, fish; small amounts in egg yolk, whole grains. Linolenic – n-3 Fatty Acid • Unique functions and properties – May be required for development of visual acuity – Lowers blood triglycerides – High intakes prolong bleeding time – Anti-inflammatory properties – Enhances the immune system – May reduce heart disease and cancer risk: In Japan, where n-3 fatty acid intake is much greater than in the US heart attacks are four times less common! Linolenic Acid • Requirement: Minimum of 0.5% of total kcal or a total of 10 kcal from linolenic acid. This amount is supplied by 1 tablespoon canola oil • Good food sources: flaxseed, English walnuts, canola oil, soy oil, ocean fish • Also contained in egg yolk, dark green leafy vegetables, whole grains Linolenic acid • • • • The ratio of dietary linoleic and linolenic acids seems to be important for heart disease and cancer prevention. – N-6/n-3 ratio tends to be high in the American • diet (range from 10:1 to 50:1) • – Recommended ratio 4:1 Ratio of Essential Fatty Acids Achieving a balanced ratio of essential FAs usually involves finding ways to increase linolenic acid – Use primarily soy and canola oils (read food labels for these) – Avoid hydrogenated oils (these lower the essential fatty acid content of vegetable oils) – Avoid substituting reduced fat or fat free products for products containing linolenic acid (salad dressings) – Maintain eggs in the diet – Use some flaxseed – Eat dark green leafy vegetables very often – May include ocean fish in the diet Cis and Trans Fatty Acids 2 isomeric forms of fatty acids exist – Cis and trans fatty acids have the same chemical formula, just a different configuration around the double bond. Cis and Trans Fatty Acids The TRANS configuration Cis and Trans Fatty Acids • The cis configuration occurs most often in nature • Trans configuration – Occurs naturally in small amounts in some foods (beef, lamb, milk fat) – Most trans FAs in foods are a byproduct of the industrial hydrogenation of vegetable oils. Hydrogenation adds hydrogens to unsaturated fatty acids to make them more saturated. This improves the stability of vegetable oils and makes them more solid at room temperature. In the – process, the configuration of some double bonds changes from cis to trans. Hydrogenation is used in the production of margarine from oil. hydrogenation soybean oil soybean margarine Trans Fatty Acids • Americans eat about 5 g trans fat/day The problems with trans Fat – Trans fatty acids do not relieve symptoms of essential fatty acid deficiency. In fact hydrogenation destroys some of the essential fatty acids in the oils. It also inactivates the vitamin K in the oil. • Trans fatty acids act similarly to saturated fatty acids in raising blood cholesterol and insulin levels. • Although the amount of trans fatty acid in most foods is less than the amount of saturated fatty acid, it is advisable to avoid them. Trans Fatty Acids (cont) Minimize intake of trans fatty acids by limiting intake of hydrogenated fats. Look for the word “hydrogenated” in the list of ingredients on the food label. – Use vegetable oils and softer margarines as spreads and in recipes. – Limit or avoid use of solid margarines, vegetable shortening (Crisco). – Limit or avoid high fat commercial baked goods— donuts, muffins, cookies, cakes. – Limit or avoid restaurant fried foods, high fat foods. Summary- Types of Fats Why would it be undesirable to eliminate fat from our diet? Answers • We need essential fatty acids. • Substrate for eicosanoid synthesis would be reduced. • A fat free diet would greatly reduce the absorption of fat soluble vitamins and carotenoids. • Fat provides a concentrated source of kcal. • Eliminating fat would make it difficult to maintain a stable weight. • Fat makes eating more pleasurable. How can we obtain a healthful balance of fatty acids in our diets? Graphics: Microsoft Online, USDA Food and Nutrition Services Ingrid Adams, Ph.D., R.D. L.D. Associate Professor , Nutrition and Food Science, University of Kentucky Extension Specialist for Physical Activity and Weight Management Date: February 27, 2015 Policy The Cooperative Extension Service is federally mandated to take affirmative steps to ensure that its programs and services are available to all people. One step is public notification of its intention to serve all audiences. All Extension materials intended for public distribution must include the following statement: Educational programs of Kentucky Cooperative Extension serve all people regardless of race, color, age, sex, religion, disability, or national origin. Letterhead, enclosure slips, and newsletters must also include the following "cooperating" statement: UNIVERSITY OF KENTUCKY, KENTUCKY STATE UNIVERSITY, U.S. DEPARTMENT OF AGRICULTURE, AND KENTUCKY COUNTIES,