Chapter Lecture Chapter 5: Lipids: Essential Energy-Supplying Nutrients © 2017 Pearson Education, Inc What Are Lipids? • Lipids • Diverse group of molecules that are insoluble in water • Fats • The lipid content of diets and foods © 2017 Pearson Education, Inc What Are Lipids? (cont.) • Three types of lipids are found in foods and in body cells and tissues: • Triglycerides • Phospholipids • Sterols â 2017 Pearson Education, Inc Triglycerides Triglycerides (also called triacylglycerols) contain: • Three fatty acid molecules • One glycerol molecule © 2017 Pearson Education, Inc Triglycerides (cont.) • Fatty acids are classified by the type of fatty acids attached to the glycerol backbone • Fatty acids can vary by: • Carbon chain length • Saturation level • Shape © 2017 Pearson Education, Inc Triglycerides: Chain Length • • • • Short-chain fatty acid (< carbon atoms) Medium-chain fatty acid (6–12 carbon atoms) Long-chain fatty acids (≥14 carbon atoms) Carbons can be numbered • Carboxyl end (COOH): α-carbon (alpha—first) • Methyl end (CH3): Ω-carbon (omega—last) • Fatty acid chain length determines method of lipid digestion, absorption, metabolism, and use © 2017 Pearson Education, Inc © 2017 Pearson Education, Inc Triglycerides: Saturation • Saturated fatty acids have hydrogen atoms surrounding every carbon in the chain (no double bond) • Monounsaturated fatty acids lack one hydrogen atom (one double bond) • Polyunsaturated fatty acids have more than one double bond © 2017 Pearson Education, Inc â 2017 Pearson Education, Inc Triglycerides: Shape Level of saturation affects fatty acid shape • Saturated fatty acids form straight, rigid chains, packed tightly together • Saturated fatty acids are solid at room temperature • Animal fats, butter, and lard are high in saturated fatty acids © 2017 Pearson Education, Inc Cardiovascular Disease (cont.) • Risk factors for cardiovascular disease: • Being overweight • Physical inactivity • Smoking • Type diabetes • Inflammation • Abnormal blood lipids © 2017 Pearson Education, Inc © 2017 Pearson Education, Inc Cardiovascular Disease (cont.) • Dietary fats increase blood lipids • Highly saturated and trans fat intakes increase blood cholesterol • Omega-3 fatty acids reduce inflammation and blood triglycerides © 2017 Pearson Education, Inc Cardiovascular Disease (cont.) • Blood lipids include: • Chylomicrons—present only after a meal • Very-low-density lipoproteins (VLDL) • Low-density lipoproteins (LDL) • High-density lipoproteins (HDL) © 2017 Pearson Education, Inc © 2017 Pearson Education, Inc Cardiovascular Disease (cont.) • Diets high in saturated fats • Decrease the removal of LDLs from the blood • Increase blood cholesterol levels • Contribute to the formation of plaques that can block arteries © 2017 Pearson Education, Inc © 2017 Pearson Education, Inc Cardiovascular Disease (cont.) • Diets high in trans fatty acids: • Can raise blood levels of LDL-cholesterol as much as saturated fat • Are abundant in hydrogenated vegetable oils (margarine, baked goods, fried foods) • FDA requires that trans fatty acid content be listed on labels for conventional foods and some dietary supplements © 2017 Pearson Education, Inc Cardiovascular Disease (cont.) • Lifestyle changes can prevent or reduce cardiovascular heart disease • Follow DRIs for total fat, saturated fat and trans fat • Increase omega-3 fatty acids • Increase intake of whole grains, fruits and vegetables; dietary fiber: 20−30 grams per day • Consume RDA of vitamins B6, B12, and folate • Select and prepare foods with less salt Eat smaller meals and snacks â 2017 Pearson Education, Inc Cardiovascular Disease (cont.) • Lifestyle changes can prevent or reduce cardiovascular heart disease • Add plant sterols to your diet • Maintain normal blood glucose level • Maintain a healthy body weight • Maintain an active lifestyle • No more than alcoholic beverages per day for men and drink per day for women • If you smoke, stop © 2017 Pearson Education, Inc ABC News Video: Mediterranean Diet Could Help Reduce Heart Disease © 2017 Pearson Education, Inc Cardiovascular Disease (cont.) • Medicines help reduce risk • Endogenous cholesterol synthesis inhibitors: statins • Bile acid sequestrants Nicotinic acid â 2017 Pearson Education, Inc High-Fat Diets and Cancer • Three types of cancer have been studied extensively for their possible relationship to dietary fat intake: • Breast cancer • Colon cancer • Prostate cancer © 2017 Pearson Education, Inc High-Fat Diets and Cancer (cont.) • Until the links with cancer are settled, the American Institute for Cancer Research recommends these common-sense rules: • Maintain a healthy body weight • Engage in moderate physical activity at least 30 min/day • Limit intake of sugary foods, empty Calories, red meats, salty foods, and alcohol • Eat a variety of fruits, vegetables, and wholegrain foods Don't use supplements to protect against cancer â 2017 Pearson Education, Inc Nutri-Tool: Build-a-Pizza PLAY © 2017 Pearson Education, Inc Build-a-Pizza ... (cont.) • Chylomicrons are transported out of the enterocyte, then: • Travel through the lymphatic system • Are transferred to the bloodstream through the thoracic duct • Short- and medium-chain... pack together tightly • Unsaturated fatty acids are liquid at room temperature • Hydrogen atoms can be arranged in different positions at the point of unsaturation: • Cis: same side of the carbon... rings of carbon atoms • Plant sterols appear to block the absorption of dietary cholesterol • Cholesterol is found in animal-based foods as cholesterol esters • Cholesterol is made in in the liver