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Why Are the Eight Essential Amino Acids Important?

author image Janet Renee, MS, RD
Janet Renee is a clinical dietitian with a special interest in weight management, sports dietetics, medical nutrition therapy and diet trends. She earned her Master of Science in nutrition from the University of Chicago and has contributed to health and wellness magazines, including Prevention, Self, Shape and Cooking Light.
Why Are the Eight Essential Amino Acids Important?
Essential amino acids are found in foods such as meats and poultry. Photo Credit Julia Volodina/iStock/Getty Images

As building blocks of protein, amino acids are important to the health and proper function of your body. There are 22 amino acids your body uses, 14 of which your body manufactures on its own and the remainder of which you receive through your diet. The remaining eight amino acids are considered essential because your body cannot manufacture them. Amino acids are involved in many bodily functions and work together to promote health.

Isoleucine and Leucine

Amino acids are found in foods such as meats, poultry, eggs, fish, cheese and seeds. Leucine and isoleucine are two of three branched-chained amino acids that make up a third of your muscle tissue. They provide muscle fuel, making them a common supplement for athletes. In addition, isoleucine is a necessary part of hemoglobin, the oxygen-carrying protein in red blood cells. Both amino acids help muscles recover from strenuous activity and boost endurance.

Lysine and Methionine

Lysine is needed for intestinal absorption of calcium and is necessary for collagen formation, a protein that makes up your bones, ligaments, cartilage and tendons. In conjunction with vitamin C, lysine produces hydroxylysine, a substance incorporated into collagen. It also helps produce antibodies, making it an important part of your immune system. Methionine is also involved in collagen formation and has the added function of helping the liver metabolize fats. Methionine is an antioxidant your body uses to neutralize and prevent damage by highly charged, unstable molecules known as free radicals.

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Phenylalanine and Threonine

Phenylalanine plays a critical role in producing important brain chemicals. Your body converts phenylalanine to another amino acid called tyrosine, which is responsible for manufacturing epinephrine, norepinephrine and thyroid hormones, chemicals that help regulate mood, appetite, metabolism and sleep-wake cycles. Threonine helps your body stabilize blood sugar and is necessary for the formation of tooth enamel, collagen and elastin, a substance that contributes to muscle, skin and tendon flexibility.

Typtophan and Valine

The last of the eight essential amino acids -- tryptophan and valine -- play equally important roles in the proper function of your body. Tryptophan's primary function is to produce serotonin, a brain chemical involved in mood regulation; a deficiency of serotonin contributes to depression and anxiety. Valine is responsible for promoting growth, tissue repair and blood sugar regulation.

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