Tryptophan is an essential amino acid that is naturally present in meat, dairy, eggs, and some nuts and seeds. For a variety of reasons, tryptophan is sometimes consumed in lower quantities than other amino acids. It is considered a necessary nutrient for the production of the neurotransmitter serotonin, and deficiencies in tryptophan have been associated with dementia, depression, and insomnia. For that reason, susceptible individuals may choose to take a tryptophan supplement to meet dietary needs. Normally taken as a pill or capsule, supplemental tryptophan is currently available either in its pure form, as l-tryptophan, or as a downstream compound that is normally synthesized from tryptophan within the brain.
As a nutrient, tryptophan is generally less plentiful than other amino acids, particularly in non-meat sources, such as corn, cereal grains, and legumes. It is most available from animal products — including meat, eggs, and dairy — as well as some seeds and nuts. Even in these foods, other amino acids such as tyrosine and phenylalanine tend to compete with tryptophan for absorption. Additionally, vitamin B6, vitamin C, and folic acid are usually required for the absorption and assimilation of tryptophan. Each of these factors can contribute to a dietary deficiency, necessitating the use of a tryptophan supplement for some people.
Even when dietary intake is adequate, this does not necessarily correlate with increased serum levels, and supplemental tryprophan does not always produce increased levels of serotonin. As an alternative to a tryptophan supplement, some prefer to take 5-hydroxytryptophan (5-HTP). When the brain processes tryptophan to synthesize serotonin, it first converts the amino acid to 5-HTP, an intermediary neurotransmitter in the production process. This supplement appears to actively increase serotonin levels in the brain, and has a measureable effect on mood balance, quality of sleep, and fibromyalgia symptoms.
Between 1989 and 2001, tryptophan supplements were not available for over-the-counter purchase in the U.S. A particular manufacturer was identified as having allowed contaminated supplements enter the supply, resulting in thousands of reported illnesses and several deaths from a bacterial disease known as eosinophilia-myalgia syndrome. As a reaction to the outbreak, the United States Food and Drug Administration (FDA) banned the import and sale of tryptophan supplements, although the product continued to be available in Canada and parts of Europe. The FDA lifted the ban in 2001, and tryptophan supplements began to trickle back into the U.S. market.
Any tryptophan supplement should be taken with caution. As a serotonin producer, it can interact with other substances to create an overabundance of serotonin in the brain. Certain antidepressants, sleep aids, or pain medications may interact badly with tryptophan and 5-HTP. It is advisable to consult a doctor or pharmacist before taking a tryptophan supplement, or to add a different drug or supplement to an existing tryptophan treatment program.