Chapter 5 Fats Oils and Other Lipids 2012 Pearson Education Inc Objectives for Chapter 5 Describe the three classifications of lipids Explain the differences in the structure of triglycerides phospholipids and cholesterol Describe how fat is digested and absorbed in the body Explain how fat is transported in the blood Describe the functions of fat in the body Define the dietary recommendations for total fat the essential fatty acids cholesterol and trans fat Identify the major food sources of the different types of fats including the essential fatty acids saturated fats and trans fats Compare the different fat substitutes currently used in food products Describe the development of atherosclerosis including its role in the risk of heart disease Explain how lifestyle factors can affect the risk for heart disease Nutrition and You 2e 2012 Pearson Education Inc What Are Fats and Why Do You Need Them Lipids category of compounds containing carbon hydrogen and oxygen that are hydrophobic insoluble in water Fat is the common name for just one type of lipid known as a triglyceride Fats serve multiple functions in foods Give flaky texture to baked goods Make meats tender Provide flavor and aromas Contribute to satiety Nutrition and You 2e 2012 Pearson Education Inc What Are Fats and Why Do You Need Them Fats and other lipids perform important functions in the body Energy storage Insulation Transport of proteins in blood Cell membrane structure Three types of lipids found in foods and in your body Triglycerides fats phospholipids and sterols Basic unit of triglycerides and phospholipids fatty acids Nutrition and You 2e 2012 Pearson Education Inc Structure of a Fatty Acid Figure 5 1 Nutrition and You 2e 2012 Pearson Education Inc Fatty Acids Are Found in Triglycerides and Phospholipids Fatty acids chain of carbon and hydrogen atoms with acid group COOH at one end Nutrition and You 2e Over 20 different fatty acids Can vary by 1 length of chain 2 whether carbons have double or single bonds between them 3 total number of double bonds 2012 Pearson Education Inc Saturated and Unsaturated Fatty Acids Figure 5 2 Nutrition and You 2e 2012 Pearson Education Inc Fatty Acids Vary in Length and Structure Saturated fatty acids all carbons bonded to hydrogen Example stearic acid 18 carbons solid at room temperature Unsaturated fatty acids one or more double bond between carbons less saturated with hydrogen More liquid at room temperature Monounsaturated fatty acids one double bond Example Oleic acid 18 carbons olive oil Polyunsaturated fatty acids more than one double bond Example essential fatty acids linoleic and alpha linolenic acids soybean oil Nutrition and You 2e 2012 Pearson Education Inc Saturated and Unsaturated Fatty Acids Help Shape Foods Figure 5 3 Nutrition and You 2e 2012 Pearson Education Inc Triglycerides Contain Three Fatty Acid Chains Triglyceride three fatty acids connected to glycerol backbone Most common lipid found in foods and body Referred to as fats Saturated fats have mostly saturated fatty acids Unsaturated fats have mostly unsaturated fatty acids Nutrition and You 2e 2012 Pearson Education Inc Structure of a Triglyceride Figure 5 4 Nutrition and You 2e 2012 Pearson Education Inc Phospholipids Contain Phosphate Phospholipids have glycerol backbone but two fatty acids and a phosphorus group Phosphorus containing head is hydrophilic Fatty acid tail is hydrophobic Cell membranes made of phospholipid bilayer Major phospholipid in cell membrane lecithin Lecithin used as emulsifier in foods such as salad dressings to keep oils and water mixed together Nutrition and You 2e 2012 Pearson Education Inc Structure of a Phospholipid Figure 5 5 Nutrition and You 2e 2012 Pearson Education Inc Phospholipids Role in Your Cell Membranes Figure 5 6 Nutrition and You 2e 2012 Pearson Education Inc Keeping a Salad Dressing Blended Figure 5 7 Nutrition and You 2e 2012 Pearson Education Inc Sterols Have a Unique Ring Structure Sterols are comprised mainly of four connecting rings of carbon and hydrogen Example cholesterol Important role in cell membrane structure Precursor of important compounds in body Not required in diet since body makes all cholesterol needed Nutrition and You 2e 2012 Pearson Education Inc Structure of a Sterol Figure 5 8 Nutrition and You 2e 2012 Pearson Education Inc Three Types of Lipids Figure 5 9 Nutrition and You 2e 2012 Pearson Education Inc Animation Lipid Absorption Nutrition and You 2e 2012 Pearson Education Inc What Happens to the Fat You Eat Mouth chewing lingual lipase Stomach gastric lipase diglyceride and one fatty acid Small intestine Bile acids emulsify fat Pancreatic lipase two fatty acids and glycerol Lecithin in bile packaged with monoglycerides and fatty acids to create micelles for absorption Short chain fatty acids enter bloodstream and travel to liver Long chain fatty acids enter lymph and need transport carriers Nutrition and You 2e 2012 Pearson Education Inc Digesting and Absorbing Fat Figure 5 10 Nutrition and You 2e 2012 Pearson Education Inc Animation Fat Digestion Nutrition and You 2e 2012 Pearson Education Inc What Happens to the Fat You Eat Lipoproteins transport fat through the lymph and blood Chylomicrons carry digested fat through lymph into bloodstream Very low density lipoproteins VLDL deliver fat made in liver to cells Low density lipoproteins LDL bad cholesterol deposit cholesterol on walls of arteries High density lipoproteins HDL good cholesterol remove cholesterol from body and deliver to liver for excretion Nutrition and You 2e 2012 Pearson Education Inc Chylomicron Figure 5 11 Nutrition and You 2e 2012 Pearson Education Inc Lipoproteins Figure 5 12 Nutrition and You 2e 2012 Pearson Education Inc Roles of Lipoproteins Figure 5 13 Nutrition and You 2e 2012 Pearson Education Inc How Does Your Body Use Fat and Cholesterol Fat An energy dense source of fuel 9 calories per gram Glucagon also stimulates release of fat from fat cells to fuel heart liver and muscle Is needed for absorption of fat soluble vitamins A D E K and carotenoids Insulates body to maintain body temperature Cushions bones organs nerves Nutrition and You 2e 2012 Pearson Education Inc How Does Your Body Use Fat and Cholesterol Two polyunsaturated fatty acids linoleic acid an omega 3 fatty acid and alpha linolenic acid an omega 6 fatty acid are essential Eicosanoids hormone like substances involved in inflammation blood clotting blood pressure The essential fatty acids help