Amino acids are important to our body's proper functioning. Amino acids role includes repairing muscles, organs, nails, hair, skin, ligaments, and glands. Hundreds of different amino acids exist in nature, and about two dozen of them are vital to human nutrition. There are two types of amino acids: essential amino acids and nonessential amino acids. Essential amino acids are amino acids that cannot be synthesized in the body in adequate amounts and must be obtained from the diet. The essential amino acids are isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Nonessential amino acids are manufactured within the body by combining two or more essential amino acids. A dietitian could also include the amounts of non-essential amino acids you eat.