Amino acids are some of the most basic building blocks of human bodies; indeed, of life itself.
Functions of Amino Acids in the Body
Amino acids are used throughout the body for a wide variety of functions; the most obvious and well-known is in the formation of proteins, which are built of chains of amino acids. According to "The Chemistry of Amino Acids" (The Biology Project, University of Arizona, September 30, 2003), "Proteins not only catalyze all (or most) of the reactions in living cells, they control virtually all cellular processes." Interestingly, the complete proteins we take in through the diet – even from animal sources – are not used directly, but instead broken down into their component parts – yes, amino acids – and then used to reconstruct new proteins in the body.
Amino acids also form the basis of enzymes and hormones, which are types of proteins. Enzymes act as the catalyst for all manner of biochemical reactions within the body — including breaking down ingested proteins into their component amino acids. Hormones act as the body's messengers, carrying communication to and from different parts of the body.
Essential Amino Acids and Nonessential Amino Acids
There are a total of twenty amino acids needed in the human body. They are generally divided into two or three groups: essential amino acids, which the body is unable to synthesize from other components, usually consisting of 8-10 amino acids, and nonessential amino acids, which the body can synthesize; the third group that is sometimes considered is 'semi-essential' amino acids, which some bodies can synthesize and some can't, such as children's bodies.
The most common version of the list of essential amino acids is as follows:
- Isoleucine
- Leucine
- Lysine
- Methionine
- Phenylalanine
- Threonine
- Tryptophan
- Valine
However, because of a variety of reasons affecting the synthesization process, it is difficult to truly define which amino acids fit into which category. One study, published by Peter J. Reeds (Journal of Nutrition. 2000;130:1835S-1840S.), concluded that in the strictest sense, "there are only three indispensable amino acids (lysine, threonine and tryptophan) and two dispensable amino acids (glutamate and serine)." The rest, this study claims, fall into the "conditionally essential" category.
It is easy to see, therefore, that it is important to get a full complement of amino acids in the diet.
Where to Get Amino Acids in the Diet
There is some contention on which foods are best to get all the amino acids the body requires. For instance, most people know that dark turkey meat and milk are high in tryptophan, which is blamed for the drowsy effect many people experience after consuming them; but ounce for ounce, egg whites have a much higher tryptophan content than either – four times the amount in turkey, and more than a hundred times the content of milk – followed very closely by spirulina, a blue-green algae.
There are a few plant sources, such as quinoa (Wonders of the Supergrain Quinoa) and chlorella algae (Chlorella Algae, Nutrition Supplement Superfood), which provide a nearly complete set of amino acids, including all of the generally accepted list of essential amino acids.
However, few people want to eat large amounts of a single food just because it is a complete source of nutrients. Thus, perhaps the single most important way to assure a full complement of amino acids in the diet is to eat a healthy and varied diet, making sure to include plenty of legumes (beans), grains, seeds and nuts – a list which, incidentally, is also the guideline on how to be sure to include vitamin E in the diet, a powerful antioxidant.
Under normal circumstances, as long as a good varied diet is followed, few people actually need to supplement amino acids — not even athletes, contrary to popular belief. In fact, in many cases, excessive protein consumption can even be dangerous, most notably stressing kidney function, but potentially causing several other health complications.
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