Amino acids are the basic components of proteins. They play an important role in bone, muscle, blood and body organ maintenance. Out of the 22 known amino acids found in the human body, 13 can be produced by the body, which means that the other nine must be obtained from diet or other sources, like supplements.
General Information
Amino acids are often described as beads on a long chain. Different combinations of beads, or amino acids, form different necklaces, or proteins. The quality of protein depends on the type of amino acids that are present. Protein that is found in animal sources is called complete protein because it contains all of the essential amino acids, which cannot be produced by the body. Other proteins, such as those that are found in plant foods, are missing one or several of the essential amino acids.
Essential Amino Acids
Essential amino acids cannot be produced by the body and must be obtained from dietary sources. There are nine essential amino acids: histidine, isoleucine, leucine, methionine, phenylalanine, threonine, tryptophan and valine. Arginine is a tenth essential amino acid that is often not mentioned, since it is only required for children. Essential amino acids are not stored by the body, which makes it even more important that they are consumed in foods on a regular basis.
Non-Essential and Conditional Amino Acids
Non-essential amino acids are manufactured by the human body and do not require dietary intake. Some are formed during the breakdown of essential amino acids, and others are produced during protein synthesis. The non-essential amino acids include alanine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine and tyrosine. Some of these amino acids, such as cysteine, glutamine, tyrosine, glycine, proline and serine, are further classified as conditional amino acids, since they are really only needed in times of illness or stress, as noted by MedlinePlus.
Other Considerations
If you don't obtain the essential amino acids in your diet, discuss supplements with your doctor. Vegans and vegetarians should be especially careful to obtain complete proteins every day by combining different foods, like beans and rice. Food sources of essential amino acids include milk, cheese, eggs, certain meats, vegetables, nuts and grains. You don't have to combine proteins at the same meal to provide a complete protein. For example, you can have beans at lunch and a side of rice with your dinner and still consume a complete protein.
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