Tryptophan is an essential amino acid used to make niacin, the neurotransmitter serotonin, and the hormone melatonin. Tryptophan has an antidepressant effect, and is essential for mood control and normal sleep patterns. It is able to regulate hyperactivity in children, reduce stress, help the heart, and stimulate the release of a growth hormone needed to make Vitamin B-6. Vitamin B-6 is necessary for making tryptophan, which is in turn necessary for making serotonin. Tryptophan is used to treat migraines and reduce heart and artery spasms. In combination with lysine, tryptophan reduces cholesterol. Because it increases body levels of serotonin, which signals feelings of fullness, tryptophan has been indicated as a weight loss aid. Deficiency is likely to cause insomnia and adverse changes in mood.
The mood elevating effects of tryptophan are well documented. One study indicates a correlation between low tryptophan intake and increased suicide rates. Other evidence indicates tryptophan is just as effective as traditional antidepressants in some patients.
Tryptophan has not been available in the United States since 1989. An outbreak of a new blood disorder called eosinophilia-myalgia syndrome (EMS) was linked to a contaminated shipment of supplements from Japan, and the federal government recalled all products in which tryptophan was the sole or major component. However, many experts now agree that the danger associated with the amino acid is misguided. Tryptophan remains available outside of the United States.
Pregnant women and persons on MAO-inhibitors should avoid taking tryptophan.