 Chap 3  J Pistack MS/ED

FATS  Lipids – the true name for fats of all kinds  Lipids include true fats, oils, and the related lipoids and sterols  Dietary fats are found in both plant and animal products  Lipids are insoluble in water and are greasy to the touch

FATS  Animal fats consist of a larger content of saturated fat, tend to have a higher melting point, and are solid at room temperature  Plant derived fats have more unsaturated fat than animal fats, are normally in the form of oils, and have a lower melting point

FATS  Comprise elements carbon, hydrogen, and oxygen  The basic structural unit of a true fat is one molecule of glycerol attached to one, two, or three fatty acids  A fatty acid is composed of a chain of carbon atoms with hydrogen and a few oxygen atoms attached

COMPOSITION OF FATS  Monoglycerides - one fatty acid attached to glycerol  Diglycerides – two fatty acids attached to glycerol  Triglycerides – three fatty acids attached to glycerol

COMPOSITION OF FATS  Fatty acid carbon chains vary in length from 2 to 24 carbon atoms  The length of the chain determines how the body transports and processes the fatty acid  Short <6  Medium 8-12  Long  The length of the chain has dietary implications

 Saturated, trans-fat, unsaturated, monounsaturated, and polyunsaturated are names indicating the degree of hydrogen atom saturation of the carbon chain of a fatty acid  A saturated fatty acid is filled with as many hydrogen atoms as the carbon atoms can bond with – thus, it is saturated

 In an unsaturated fatty acid the carbon atoms are joined together by one or more double bonds, not holding its maximum number of hydrogen atoms and is therefore unsaturated  Double bonds between two carbon atoms when there are two few hydrogen atoms to fill all the spaces

 A monounsaturated fatty acid has only one carbon to carbon double bond  A polyunsaturated fatty acid has more than one carbon to carbon double bond

SATURATED FATS  Solid at room temperature  Animal or tropical oil origin  Become rancid slowly – because of their chemical stability  Products made with this fat have a longer shelf life  All of the carbons are attached to hydrogen with no double bonds

UNSATURATED FATS  Liquid at room temperature  Plant origins  Become rancid quickly  Have a double carbon bond (one or more hydrogen atoms could be added to the fatty acid chain)  A double bond on a fatty acid causes the chain to bend or change shape  Has a health benefit

 The addition of hydrogen to fat of vegetable origin  If enough hydrogen is added to only break some of the double bonds the fat is considered partially hydrogenated  If all double bonds are broken with added hydrogen the fat is completely hydrogenated

TRANS FATTY ACIDS  Made from unsaturated fats by commercially adding hydrogen at double-bond sites  Causes an unnatural bend in the fatty acid chain  Has a health detriment

FUNCTIONS OF FATS  Fats serve as a fuel source as well as a vehicle for fat-soluble vitamins –A, D,E, and K  Due to the chemical composition of fats they are a more concentrated energy source than carbohydrates  Gram for gram, fats furnish twice as many calories as carbohydrates

FUNCTIONS OF FATS  Seven major functions of fats in the body  1 - Supply fuel to most tissues  2 - Serves as an energy reserve  3 - Insulate the body  4 – Support and protect vital organs  Act as a pad to absorb mechanical shock  Protected organs include eyes and kidneys

FUNCTIONS OF FATS  5 - Lubricate body tissues  Oils manufactured by the body supply glands like the sebaceous glands, to secrete the oils to the skin to control water loss  6 - Form an integral part of cell membranes  Plays a role in drug, nutrient, and metabolite transport  Provides barrier against water soluble substances  7 -Carrier for fat-soluble vitamins

 Not a true fat but belongs to a group called sterols  Cholesterol is a component of many foods we eat  Our bodies make about 1000 mg a day  Present only in animal foods

 A component of bile salts that aid digestion  Essential component of cell membranes  Found in the brain, nerve tissue, and blood  Precursor for steroid hormone production  Necessary for the production of  Cortisone  Adrenaline  Estrogen  Testosterone

 Dietary fat plays a key role in health  Some fat in the diet is necessary for optimal health  Adds satiety and palatability (flavor)  Good fats are found in nuts, avocado, canola, olive, and peanut oil  Polyunsaturated fats are the form of omega 3 and omega 6