Tryptophan is an amino acid, a protein without which humans could not survive. It comprises one of the building blocks of DNA and is vital to the production of serotonin and melatonin. It is also widely accessible in dairy foods, bananas, chocolate and poultry.
Certain old-fashioned cures for sleeplessness were based on the consumption of foods with tryptophan. For example, drinking a glass of milk before bed was said to aid in sleeping. Though people were unaware at the time that this amino acid existed, it is clear that such early prescriptions for increasing sleepiness were at least mildly effective. Today, one may hear similar prescriptions for including tryptophan foods in the diet not only to promote sleep but also to improve mood.
Since serotonin is produced through the action of tryptophan, low levels of it in the body may result in depression or anxiety. Most drugs that treat anxiety and depression do not, however, supplement this amino acid, but inhibit serotonin from being too quickly absorbed by the brain. The increased level of free serotonin is thought to decrease anxiety and depression, and is frequently effective. Though unproven, those who suffer from anxiety or depression might also be able to increase their serotonin levels by adding tryptophan-rich foods to their diet. Including dairy products, which are also thought to help trim waistlines, may make antidepressants more effective.
In the US in the late 1980s, tryptophan supplements were linked to an outbreak of a serious bacterial autoimmune disorder, eosinophilia-myalgia syndrome. This disease was deadly, and as a result, the supplements were pulled from the US market.
Further studies revealed that the bacteria used to culture manufactured tryptophan were causing the disease, and that the specific bacteria were only being used by a Japanese manufacturer who had provided about 70% of supplements in the US. This disease did not occur with supplements grown from other bacteria, and therefore its occurrence was mostly connected with those who obtained their supplements in the US. No cases were reported in Britain and most of Europe, where it remained widely available. In 2001, the US Food and Drug Administration allowed tryptophan back on the market.
While maintaining a normal level of tryptophan is important, abnormally high levels have been linked to delusional thinking, paranoid and obsessive behavior, and other markers of schizophrenia. Some medical theorists believe that schizophrenia may be caused by the body's inability to recognize and use tryptophan properly. The result is a toxic waste product that creates psychotic symptoms.
As with any other nutritional supplement, it is advisable to seek medical advice before taking tryptophan, as it may interact with other medications or cause adverse effects. A psychiatrist may also prescribe it for those who are not benefiting from other antidepressants, or to enhance their effectiveness.