Amino acids are the building blocks of proteins. They band together in chains to form the stuff from which life is born. This is a two-step process: first, they get together and form peptides or polypeptides, and it is from these groupings that proteins are made.
A total of 20 different kinds of amino acids form proteins, with the types involved determining the shape of the proteins formed. Commonly recognized ones include glutamine, glycine, phenylalanine, tryptophan, and valine. Three of those — phenylalanine, tryptophan, and valine — are essential amino acids for humans; the others are isoleucine, leucine, lysine, methionine, and threonine. This type cannot be synthesized by the body, so they must be ingested through food.
One of the best-known essential amino acids is tryptophan, which performs several critical functions for people. It helps induce normal sleep; helps reduce anxiety, depression, and artery spasm risk; and helps produce a stronger immune system. Tryptophan is perhaps most well-known for its role in producing serotonin, which is what gets all the press at Thanksgiving time for putting people to sleep after the big holiday feast.
Amino acids make up 75% of the human body. They are essential to nearly every bodily function, and every chemical reaction that takes place in the body depends on them and the proteins that they build.
The essential amino acids must be ingested every day. Failure to get enough of even one of them can result in protein degradation, because the human body does not store them for later use, as it does with fats and starches. Amino acids can be found in many places in nature, and more than 300 have been found in the natural world from such diverse sources as microorganisms and meteorites.