Transcript Document
Chapter 5 1 FATS Key Concepts 2 Fat is an essential nutrient Foods from both animal and plant sources supply forms of fat . Excess dietary fat is a negative risk factor in overall health. Fats 3 The term fats actually refers to the chemical group called lipids. Lipids are divided into three classifications: 1. fats (triglycerides) 2. fat-related substances of phospholipids 3. sterols Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 4 The Nature of Fats 5 Dietary importance Storage form of fuel Supplement to CHO as an energy source Carbon,hydrogen, oxygen Lipids – overall name for fats and fatty substances Insoluble in water, greasy The Nature of Fats 6 Triglycerides: 3 fatty acids + glycerol Fatty acids: chain of carbon, hydrogen and oxygen Amount & composition of fatty acids leads to different taste and smell Types of fatty acids: 1. Saturated 2. Unsaturated 3. Monounsaturated, Polyunsaturated, Trans fats 4. Essential Fatty Acids 7 Saturated Heavier, denser, solid • Coconut oil, meats, dairy, eggs Unsaturated Less heavy, less dense Monounsaturated (olive oil, almonds, peanuts, avocadoes), Polyunsaturated (vegetable oils – corn, safflower) Essential Body must have, otherwise deficient Body cannot produce enough on its own Saturated Fats 8 Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. Fatty Acids 9 Essential fatty acids (continued) Linoleic (omega-6) Alpha-linoleic (omega-3) Both are polyunsaturated Needed for muscle tone, tissue growth, blood clotting, ht. action, cholesterol metabolism Trans Fats Hydrogenated Bad fats Butter, stick margarine, shortening Other Types of Fats 10 Lipoproteins – transport mechanism for fats in the bloodstream Low density lipoproteins (LDL) High density lipoproteins (HDL) Sterols Subgroup of steroids Made by plants & animals Cholesterol = sterol from animals Cholesterol 11 Cholesterol-waxy substance found in all tissues in humans and other animals. All foods from animal sources, such as meat, eggs, fish, poultry, and dairy products contain cholesterol. The highest sources of cholesterol are eggs yolks, and organ meats. No plant-derived food contains cholesterol. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. Cholesterol 12 A high level of cholesterol in the blood is a risk factor for Coronary Artery Disease. The amount of fat and protein determines the density or weight of the lipoprotein. The more fat and lipid substances present, the lower the density (or lighter) of the compound. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. Cholesterol 13 (LDL’s)-Low density lipoproteins carry cholesterol throughout the body to tissue cells for various functions. (HDL’s)-are formed within the cells to remove cholesterol from the cells, bringing it to the liver for removal. A total blood cholesterol reflects the level of cholesterol contained in LDL and HDL. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. Cholesterol 14 LDL levels reflect the amount of cholesterol brought to the cells that have the potential to be dropped off and clog vessels and arteries. This is known as plaque, (fatty deposits), that attach to the walls of the vessels. HDL’s remove cholesterol from the circulatory system, this is a positive action and reduces CAD. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. Cholesterol 15 Dietary cholesterol should be 300mg /day or less. Major culprit that raises blood cholesterol is eating too much cholesterol due to a diet high in fat. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. Blood Cholesterol Levels 16 Desirable total cholesterol-<200mg/dL Desirable LDL-<130mg/dL LDL is known as the “bad” cholesterol because it can build up on the walls of the arteries. HDL is known as the “good” cholesterol because it is thought to remove bad cholesterol from the body. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. Fat Substitutes 17 New on market Still being tested Not absorbed, provide no calories Developed to reduce overall dietary fat intake Examples – Olestra, Simplesse Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved. 18 Functions of Fat in Foods 19 Fat in foods provide: Energy Essential nutrients • Essential fatty acids Flavor and satisfaction Insulate body (regulates temp.) Protect vital organs (adipose tissue) 20 Food Sources of Fat 21 Animal fats Mostly saturated fats Contain more cholesterol Bacon, egg yolks, ice cream, butter, cheese Lean animal fats – MUCH healthier !! Fish = great source of polyunsaturated fats & essential fats (omega 3, 6) Plant fats Mostly monounsaturated & polyunsaturated Vegetable oils Food Label Information 22 Calories from fat Calories from saturated fat* Total fat Saturated fat Polyunsaturated fat* Monounsaturated fat* Cholesterol *Voluntary information Approved Health Claims: Fats 23 Diet low in fat may reduce risk for certain cancers Diet low in saturated fat & cholesterol may reduce risk of CHD Consuming omega-3 fatty acids may reduce risk of CHD Fish oil supplements – caution with seafood allergy • Supplements made from: tuna, halibut, herring, mackeral, shark, salmon, cod liver Dietary Fat Requirements 24 Healthy diet guidelines: Low in fat, saturated fat, and cholesterol Fat content should not exceed 20% to 35% of total kilocalories **excess stored as body fat Less than 10% of kilocalories should be from saturated fat Dietary cholesterol should be limited to 300 mg/day Fats 25 Fats are needed in the body for their food value and their physiologic purpose. Foods containing fats, smell and taste good and provide satiety. Physiologic functions of fats include providing a backup energy supply, cushioning body organs and serving to regulate body temperature. Copyright © 2009, by Mosby, Inc. an affiliate of Elsevier, Inc. All rights reserved.