Tyrosine (also known as L-tyrosine, 4-hydroxyphenylalanine, or L-2-Amino-3-(4-hydroxyphenyl)-propanoic acid) is an amino acid, a building block of virtually every bodily protein. Its name is derived from the Greek word for cheese, tyros, because it was first discovered in a particular protein from cheese. Tyrosine is a major component in several important neurotransmitters (the chemicals that allow the nerves to communicate), including dopamine, epinephrine, and norepinephrine.
Tyrosine is also vital to several organs responsible for the release and regulation of important hormones. The body synthesizes tyrosine from ingested phenylketonuria, an essential amino acid, which, unfortunately, cannot be metabolized by those with a genetic disorder known as phenylketonuria (PKU). Aspartame, a well-known artificial sweetener, breaks down into several compounds in the body, one of which is phenylalanine; appropriately, several countries legally require that foodstuffs containing aspartame carry a warning for phenylketonurics.
Such people have to follow a strict diet and take special medications to counteract potential intellectual disabilities. At any rate, tyrosine can be ingested from many foods, including fish, poultry, bananas, milk, cheese, yogurt, peanuts, almonds, and sesame seeds.
Several notable studies indicate that tyrosine plays an important role in reducing stress. This is likely because of its role in the production of adrenal stress hormones. In some animal research, tyrosine supplements apparently improved the creatures’ ability to perform various tests.
In one notable human study, a group of cadets taking a stressful combat training course produced better mental performance scores than those given a carbohydrate drink. Another double-blind trial showed that tyrosine prevented a decline in mental performance in sleep-deprived participants. Science seems to support the use of tyrosine supplements for the reduction of stress.
Preliminary research suggests that tyrosine supplements may help depression, but more clinical trials need to be conducted before tyrosine can be confidently recommended as a treatment for depression. Likewise, some evidence suggests that tyrosine may be effective when used to treat alcohol withdrawal and Parkinson’s disease, but more data is need to further understand tyrosine’s effect on these conditions.