Jaymie TicknorIntro Nutrition Science 2460 Sect. 00212 June 2014Chapter #5 : Fats What Are Fats?● Lipids: a diverse group of organic substances that are insoluble in water○ Include triglycerides, phospholipids, and sterols○ Fats and oils are two different types of lipids■ Fats are solid at room temperature■ Oils are liquid at room temperatureTriglycerides Are the Most Common Food-Based Fat● Triglyceride: a molecule consisting of three fatty acids attached to a three-carbon glycerol backbone○ Also called triacylglycerols○ Most common form of fat in our diet○ The form in which most of our body fat is stored referred to as adipose tissue (metabolically active tissue)● Fatty Acids: long chains of carbon atoms bound to each other as well as to hydrogen atoms○ Contain an acid group (carboxyl group) at one end of their chain● Glycerol: an alcohol composed of three carbon atoms○ It is the backbone of a triglyceride moleculeSaturated Fats Contain the Maximum Amount of Hydrogen● Saturated Fatty Acid (SFA): a fatty acid that has no carbons joined together with a double bond○ Generally solid at room temperature○ Coconut oil, palm kernel oil, butter, cream, whole milk, and beef (animal-based 40-60% energy)Unsaturated Fats Contain Less Hydrogen● Monounsaturated Fatty Acid (MUFA): a fatty acid that has two carbons in the chain bound to each other with one double bond○ Generally liquid at room temperature○ Olive oil, canola oil, and cashew nuts (plant foods 80-90% energy)● Polyunsaturated Fatty Acid (PUFA): a fatty acid that has more than one double bond inthe chain○ Generally liquid at room temperature○ Cottonseed, canola, corn, and safflower oilsTrans Fatty Acids Have Hydrogen Atoms on Opposite Sides● Cis fatty acid has both hydrogen atoms located on the same side of the double bond (whole foods)● Trans fatty acid hydrogen bonds are attached on diagonally opposite sides of the doublecarbon bond (cow’s milk and meat, but also in processed foods)● Hydrogenation: the process of adding hydrogen to unsaturated fatty acids, making them more saturated and thereby more solid at room temperature○ If only some of the double bonds are broken, the fat produced is called partially hydrogenatedSome Triglycerides Contain Essential Fatty Acids● Essential Fatty Acids (EFAs): fatty acids that must be consumed in the diet because they cannot be made by our body● Linoleic Acid: an essential fatty acid found in vegetable and nut oils○ One of the Omega-6 fatty acids■ Have a double bond six carbons from the omega end■ AI is 14-17 g per day for adult men and 11-12 g per day for women 19+● Alpha-Linolenic Acid (ALA): an essential fatty acid found in leafy green vegetables, flaxseed oil, soy oil, and other plant foods○ An Omega-3 fatty acid○ AI is 1.6 g per day for adult men and 1.1 g per day for adult women● Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA): omega-3 fatty acids available from marine foods and as a metabolic derivative of alpha-linolenic acid○ They are found in fish, shellfish, and fish oils○ Fish that naturally contain more oil (salmon and tuna) are higher in EPA and DHA than lean fish (cod or flounder)○ EPAs are precursors to important biological compounds called eicosanoidsPhospholipids Combine Lipids with Phosphate● Phospholipids: a type of lipid in which a fatty acid is combined with another compound that contains phosphate○ Unlike other lipids, phospholipids are soluble in water○ The liver uses phospholipids called lecithins to make bileSterols Have a Ring Structure● Sterols: a type of lipid found in foods and the body that has a ring structure○ Cholesterol is the most common sterol in our diets■ Found in animal products such as butter, egg yolks, whole milk, meats, and poultryWhy Do We Need Fats?Fats Enable the Transport of Fat-Soluble Vitamins● Dietary fat enables the transport of the fat-soluble vitamins (A, D, E, and K) our body needs for many essential metabolic functionsHow Does Our Body Process Fats?Absorption of Fat Occurs Primarily in the Small Intestine● Micelle: a spherical compound made up of bile and phospholipids that can trap the free fatty acids and monoglycerides, as well as cholesterol and phospholipids, and transport these products to the enterocytes for absorption● Lipoprotein: a spherical compound in which fat clusters in the center and phospholipids and proteins form the outside of the sphere○ Chylomicron: a lipoprotein produced in the enterocyte■ Transports dietary fat out of the intestinal tract■ Chylomicron remnants: as the cells take up the fatty acids, the chylomicrons shrink in size and become more dense○ Lipoprotein Lipase (LPL): an enzyme that sits on the outside of cells and breaksapart triglycerides, so that their fatty acids can be removed and taken up by the cellHow Much Fat Should We Eat?Dietary Reference Intake for Total Fat● The Acceptable Macronutrient Distribution Range for fat is 20-35% of total