L-tryptophan (also known as tryptophan) is an essential amino acid, which means that it must be obtained through dietary means because the body does not produce it naturally. L-tryptophan supplements are claimed to have several health benefits, such as treating depression, PMS, and ADHD. However, there is some concern that L-tryptophan supplements are not safe for public consumption, as they may cause a dangerous condition known as eosinophilia-myalgia syndrome (EMS).
(Click L-tryptophan for more information on this amino acid, including safety concerns, its effectiveness, and possible side effects.)