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Fats and Oils Chapter 4 Learning Objectives Define lipids, triglycerides, fats, and oils, and describe the roles fat plays in food. Identify foods high and low in fat, and define saturated, monounsaturated, and polyunsaturated fats and list foods in which each one is found. Describe trans fatty acids and give examples of foods in which they are found. Identify the two essential fatty acids, list their functions in the body, and give examples of foods in which they are found. Explain what EPA and DHA do in the body, and what foods they are found in. Define cholesterol, list three of its functions in the body, and give examples of foods in which it is found. Learning Objectives List four functions of fat. Discuss fat digestion, define lipoprotein, and distinguish between chylomicron, low-density lipoprotein, and highdensity lipoprotein. State recommendations for dietary intake of fat, saturated fat, trans fat, monounsaturated fat, polyunsaturated fat, and cholesterol. Distinguish between the percentage of fat by weight and the percentage of kcalories from fat. Discuss the relationship between fat intake and heart disease and cancer. Discuss the nutrition and uses of milk, dairy products, and eggs on the menu. Select fats and oils appropriately for cooking and baking. Introduction to Fats and Oils Lipid is the chemical name for a group of compounds that includes: ◦ Fats: Solid at room temperature usually from animal sources ◦ Oils: Liquid at room temperature usually from plant sources ◦ Cholesterol: found in the body ◦ Lecithin: emulsifier In foods, fat: Enhances taste and aroma Adds crispness to fried foods Makes meats juicy and tender Makes baked goods tender Carries flavors such as in an Indian curry Provides a smooth texture and creamy mouthfeel Makes food yummy! Triglycerides Most of the lipids in foods AND most of the lipids in the human body are in the form of: Triglycerides, made up of three fatty acids attached to a backbone Types of Triglycerides Saturated fat: “bad fat” A triglyceride in which the maximum number of hydrogen atoms are attached to every carbon atom— thus, the fat is “saturated” with hydrogen atoms. Monounsaturated fat: “decent fat” A triglyceride in which most of the fatty acids are monounsaturated—one fatty acid is missing a pair of hydrogen atoms in the middle. Polyunsaturated fat: “good fat” A triglyceride in which most of the fatty acids are polyunsaturated—several hydrogen atom pairs are missing. All food contains a mixture of saturated and unsaturated fats Triglycerides in Foods Fats have a “bad boy” reputation that is not entirely deserved. The problem with fats has more to do with the TYPE of fat you eat rather than the QUANTITY. Most Americans need to replace saturated fat with monounsaturated and polyunsaturated fat to decrease heart disease risk. Fat in Various Food Groups Low to No Fat Fruits and veggies (except avocado, olives, coconuts, fried veggies) Breads, cereal, rice, pasta, grains (except croissant, biscuit, cornbread, granola) Dry beans and peas Higher in Fat Fats/oils/condiments Meat/poultry/fish: Chicken w/o skin and many fish are quite low in fat. Eggs. Dairy: Regular dairy foods are high in fat. Nuts and seeds You can’t see most of the fat you get in the foods you eat. All food fats contain a mixture of saturated and unsaturated fat. Foods High in Saturated Fat Mostly animals foods ◦ Beef, pork (sausage, franks, bacon) ◦ Grains-based desserts such as cookies (made with fat and eggs ◦ Whole milk and dairy products made with whole milk such as many cheeses and ice cream ◦ French fries and other fried foods ◦ Eggs, poultry skin ◦ Also tropical oils: coconut, palm kernel, and palm oils These fats contribute to heart disease. Foods High in Monounsaturated Fat Olive oil Canola oil Safflower oil Sesame oil Avocado Nuts and seeds Peanut butter Tofu Foods High in Polyunsaturated Fat Corn oil Soybean oil Sunflower oil Nuts and seeds Fatty fish Trans Fats Occur naturally at low levels in meat and dairy Keep your intake as low as possible. Trans fats are created when vegetable oils undergo hydrogenation ◦ Liquid oils are converted to solid fats for stabilization Margarine, some fry oil, shortening ◦ Hydrogen is added to tighten up chemical structure Hydrogenation Vegetable Oils Hydrogenation Shortening Margarine Hydrogenation produces trans fatty acids, and also changes some unsaturated fatty acids to saturated fatty acids. Hydrogenation helps products stay fresh longer and gives them a higher smoking point and makes them spreadable What foods contain trans fats? Trans fats can be found in some: ◦ Fried foods like french fries and doughnuts ◦ Baked goods including pastries and cookies ◦ Pie crusts and biscuits ◦ Ready-made frosting ◦ Microwave popcorn ◦ Stick margarines and shortenings Use the Nutrition Facts label— trans fat must be listed. Essential Fatty Acids The body can make all of the fatty acids that it needs except for two: ◦ Linoleic acid (omega-6 fatty acid) ◦ Alpha-linolenic acid (ALA) (omega-3 fatty acid) Foods with Linoleic Acid (omega-6) Vegetable oils such as: ◦ soybean ◦ corn ◦ sunflower Margarine and salad dressings with vegetable oils Whole grains and vegetables also supply some linoleic acid (and ALA) Americans have no issue with getting plenty of Linoleic Acid Foods with ALA (omega-3) Several vegetable oils: ◦ Canola ◦ Flaxseed ◦ Walnut Walnuts Ground flaxseed Soy products Fatty fish Americans do not get enough ALA Functions of Essential Fatty Acids (Linoleic acid and alpha-linolenic acid) Part of cell membranes Play a role in the proper functioning of the immune system Vital to normal growth and cognitive development in infants and children There are two more omega-3 fatty acids that are heart healthy: Docosahexaenoic acid (DHA) Eicosapentaenoic acid (EPA) Soon there will likely be DRIs for DHA and EPA. Foods with DHA and EPA Fatty fish such as: ◦ Salmon, mackerel, sardines, halibut, bluefish, trout, tuna Lean fish (such as haddock, cod, flounder) contain only small amounts of DHA and EPA The fatty fish are excellent sources of DHA & EPA. ALA is found in flaxseeds, flaxseed oil, walnut oil, canola oil, and walnuts. Functions of DHA and EPA DHA is important for proper brain and eye development during pregnancy and infancy. DHA and EPA are excellent for keeping your heart healthy. They: ◦ Reduce blood pressure ◦ Reduce heart rate ◦ Reduce blood triglyceride levels ◦ Reduce blood clots (which can start heart attacks) Most Americans get PLENTY of omega-6 fatty acids—but NOT enough omega-3s. So… Eat about 8 ounces per week of a variety of seafood to provide an average of 250 mg per day of EPA and DHA. Taking in at least 250 mg per day of EPA and DHA is associated with preventing deaths from heart disease and heart disease itself. Mercury Nearly all fish and shellfish contain traces of mercury. This is a concern for pregnant women, women who may become pregnant, nursing mothers, and young children who need to avoid certain fish. Cholesterol Cholesterol is a soft waxy substances found only in animal foods. Cholesterol is needed to maintain cell membranes and is in every cell in your body. Cholesterol is needed to make: ◦ Bile acids ◦ Many hormones such as estrogen, cortisone ◦ Vitamin D Cholesterol is only in animal foods: Egg yolks Meat Poultry Milk and milk products (it is lower in lower-fat and nonfat products) Fish (shrimp is higher than other Eggs, meat, and whole milk provide most of the cholesterol we eat (and fish) these are high in saturated fat too). Cholesterol The body makes some cholesterol daily. Recommended intake from food: limit to 300 mg daily—about 4 oz. of meat, poultry, or fish contain 100 mg cholesterol. One egg has 186 mg. Men tend to take in more cholesterol than recommended. Cholesterol in your blood builds up in your arteries and is a risk factor for heart disease. Functions of Lipids About 13 to 30 percent of your weight is fat. Fat is part of all the cells in your body— provides energy (9 kcal/gram). Fat under the skin provides: ◦ Insulation—maintains body temperature ◦ Cushion—keeps critical organs safe Extra energy is stored in the body as fat ◦ Adipose cells – compact energy storage Able to swell to 20x their size We can create as many adipose cells as needed, but cannot get rid of the ones we use Functions Fat is an important part of all cell membranes. Fat transports fat-soluble vitamins in body. Certain fat-containing foods provide the body with the essential fatty acids—needed for normal growth and development, immune system, and maintain cell membranes. Digestion, Absorption, and Metabolism Fats are hard for the body to digest and absorb because triglycerides and water don’t mix. ◦ Fat is the last nutrient the body digests Minimal digestion of fats occurs before they reach the small intestine. ◦ Salivary enzymes pre-digest some, but not to an applicable degree Digestion and Absorption When fats reach the small intestine, the gallbladder releases bile into the intestine. Bile acids emulsify fat—split fat into small pieces—to allow enzymes to break down triglycerides into its fatty acids. Then the fatty acids are absorbed into the intestinal wall, where triglycerides are reformed. Lipoprotein Lipoproteins contain varying amounts of: ◦ Fats ◦ Protein ◦ Cholesterol Lipoproteins carry triglycerides around the body because their protein and phospholipids make them water soluble. Other Lipoproteins These lipoproteins are responsible for carrying cholesterol around the body. ◦ Low-density lipoprotein (LDL)—carries cholesterol to the body’s cells, called the “bad” cholesterol because the higher the level in your blood, the greater your risk for heart disease. ◦ High-density lipoprotein (HDL)—“good cholesterol”—picks up cholesterol from the cells and takes it to the liver for removal. Phospholipid - Lecithin Contains a phosphate group in place of one fatty acid Soluble in fat and water Used primarily in the industry as emulsifiers – substances capable of breaking up fat into small droplets to create a uniform mixture that wont separate In the body, lecithin helps keep the blood uniform to flow through the body. Also a big component of cell membranes Egg yolks are rich in lecithin Our liver makes enough lecithin so it is not considered an essential nutrient Dietary Recommendations Acceptable Macronutrient Distribution Ranges ◦ Over 18 years old 20 to 35 percent of kcalories Americans tend to eat too much saturated and trans fat and not enough omega-3s Dietary Recommendations Consume less than 10 percent of kcalories from saturated fat by replacing it with mono- and polyunsaturated fat. Consume less than 300 mg/day of cholesterol. Keep trans fatty acid consumption as low as possible by limiting synthetic sources. Replace protein foods that are high in saturated fats with choices lower in solid fat. Use oils to replace solid fats when possible. What does 96% fat free mean? 96 percent of the weight is lean or without fat. Only 4 percent of its weight is actually fat. It does not tell you anything about how many kcalories it has. Percent of Kcalories from Fat Percentage of kcalories from fat tells you what percent of the total kcalories come from fat. Fats and Health Heart Disease ◦ Number one killer for US men and women. ◦ Many Americans have high blood cholesterol and high blood pressure. ◦ Too much circulating cholesterol builds up in the walls of the arteries—especially the heart’s arteries—which leads to plaque accumulation. Heart Attack and Stroke Heart attack occurs when the flow of blood to a section of the heart muscle suddenly becomes blocked. Stroke occurs when the blood supply to part of the brain is cut off. If deprived of blood for more than a few minutes, parts of the heart and brain can die. What are additional risk factors for heart disease? Age Heredity Smoking High blood pressure Diabetes mellitus Obesity Cancer Cancer is the second leading cause of death in the United States. Diets high in processed meats and/or red meats and obesity have been linked with a higher risk of colon cancer. Weight gain during adulthood and obesity is linked with a higher risk of breast cancer after menopause Being overweight or obese is clearly linked to cancer of uterus, esophagus, and kidney.