disorders of nutrition
Carbohydrates, Proteins, and Fats
Fats
Fats are complex molecules composed of fatty acids and glycerol. The body needs fats for growth and energy. It also uses them to synthesize hormones and many other substances needed for the body’s activities (such as prostaglandins). Fats are the slowest source of energy but the most energy-efficient form of food. Each gram of fat supplies the body with about 9 calories, more than twice that supplied by proteins or carbohydrates. Because fats are such an efficient form of energy, the body stores any excess energy as fat. The body deposits excess fat in the abdomen (visceral fat) and under the skin (subcutaneous fat) to use when it needs more energy. The body may also deposit excess fat in blood vessels and within organs, where it can block blood flow and damage organs, often causing serious disorders. When the body needs fatty acids, it can make (synthesize) certain ones. Others, called essential fatty acids, cannot be synthesized and must be consumed in the diet. The essential fatty acids make up about 7% of the fat consumed in a normal diet and about 3% of total calories (about 8 grams). They include linoleic acid and linolenic acid, which are present in certain vegetable oils. Eicosapentaenoic acid and docosahexaenoic acid, which are fatty acids essential for brain development, can be synthesized from linolenic acid. However, they also are present in certain marine fish oils, which are a more efficient source. Linoleic acid and arachidonic acid are omega-6 fatty acids. Alpha-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid are omega-3 fatty acids. A diet rich in omega-3 fatty acids may reduce the risk of Atherosclerosis (including There are different kinds of fat: Monounsaturated Polyunsaturated Saturated Saturated fats are more likely to increase cholesterol levels and increase the risk of Atherosclerosis . Foods derived from animals commonly contain saturated fats, which tend to be solid at room temperature. Fats derived from plants commonly contain monounsaturated or polyunsaturated fatty acids, which tend to be liquid at room temperature. Palm and coconut oil are exceptions. They contain more saturated fats than other plant oils. are a different category of fat. They are man-made, formed by adding hydrogen atoms (hydrogenation) to monounsaturated or polyunsaturated fatty acids. Fats may be partially or fully hydrogenated (or saturated with hydrogen atoms). In the United States, the main dietary source of trans fats is partially hydrogenated vegetable oils, previously used in many commercially prepared foods. Consuming trans fats may adversely affect cholesterol levels in the body and may contribute to the risk of Atherosclerosis . Because of this, the US Food and Drug Administration (FDA) has banned the use of trans fats in prepared foods. Authorities generally recommend that Fat should be limited to less than about 28% of daily total calories (or fewer than 90 grams per day). Saturated fats should be limited to less than 8%. Eliminating trans fats from the diet is recommended. When possible, monounsaturated fats and polyunsaturated fats, including omega-3 fats, should be substituted for saturated fats and trans fats. People with Dyslipidemia may need to reduce their total fat intake even more. 