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Functions of Amino Acids in Protein

On average, fifteen to twenty percent of the human body is made of protein. Everything from enzymes to earlobes and hormones to hair follicles are developed from twenty-two amino acids, described as the building blocks of protein. Of these amino acids, ten must be obtained from dietary intake of proteins: arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Many people assume that protein is only required to build muscle; however, it is a fundamental macronutrient for energy metabolism, motor function, disease prevention and mental health.

Cited as one of the most vital and abundant proteins in the body, collagen provides structural integrity for cells, blood vessels, major organs, bones and connective tissue. Combined with elastin and keratin proteins, collagen also forms a strong, web-like frame for skin, hair and nails. In order to produce collagen, valine and Vitamin-C must be obtained from dietary intake. Dark red beans and fibrous fruits such as apricots, peaches, pears and pineapple are excellent dual sources of Vitamin-C and valine.

Metabolism and weight management also depend on dietary protein. Tryptophan provides appetite suppression and mood regulation to prevent emotional overeating. Leucine, methoionine and threonine help to control blood sugar levels and metabolize fat. Protein actually yields fewer available calories than an equal portion of carbohydrate because more energy is required to convert it to glucose. Foods rich in essential amino acids, and low in carbohydrates and saturated fat, include egg whites, sugar-free gelatin, chicken breast meat, orange roughy, cod, and cabbage.

Disease prevention and recovery are supported by a number of essential amino acids. Lysine helps to lower high serum triglyceride levels. Histidine, most abundant in hemoglobin, is required to produce blood cells and support immune response. Patients recovering from surgery and major corporal injuries benefit from the wound healing properties of leucine. Though supplementations of amino acids are rarely necessary for healthy individuals beyond recommended intake, increased consumption of protein may be beneficial during periods of intense physical stress or injury.

Several amino acids support neurotransmitter activity in the brain related to mood, pain management and impulse behavior. Tryptophan, a natural relaxant and mood regulator, is useful for treating insomnia, anxiety, and migraine headaches. It is also known as a calming agent for hyper-activity and anger management. Conversely, phenylalanine elevates depressed mood, increases alertness, and supports learning and memorization. Several small, high quality protein meals, rather than stimulants such as caffeine and sugar, are most effective for alertness and stress management during a hectic workday.

Protein is clearly an essential nutrient, yet a surprisingly small amount is required to support a healthy body. The U.S. Department of Health and Human Services (HHS) and U.S. Department of Agriculture (USDA) recommend 3 to 5.5 ounces of protein per day for adults, with men and active women listed at higher end the recommended daily allowance. For tips on how to select healthy sources of protein, visit the USDA online at http://www.mypyramid.gov/.