L-tryptophan is used for insomnia, sleep apnea, depression, anxiety, facial pain, a severe form of premenstrual syndrome called premenstrual dysphoric disorder (PMDD), smoking cessation, grinding teeth during sleep (bruxism), attention deficit-hyperactivity disorder (ADHD), Tourette’s syndrome, and to improve athletic performance.
L-tryptophan is naturally found in animal and plant proteins. L-tryptophan is considered an essential amino acid because our bodies can’t make it. It is important for the development and functioning of many organs in the body. After absorbing L-tryptophan from food, our bodies convert it to 5-HTP (5-hyrdoxytryptophan), and then to serotonin. Serotonin is a hormone that transmits signals between nerve cells. It also causes blood vessels to narrow. Changes in the level of serotonin in the brain can alter mood.
Eosinophiliaâ€“myalgia syndrome (EMS) is an incurable and sometimes fatal flu-like neurological condition that is believed to have been caused by ingestion of poorly produced L-tryptophan supplements. Similar to regular eosinophilia, it causes an increase in eosinophil granulocytes in the patient’s blood.
Eosinophiliaâ€“myalgia syndrome was first recognized after the doctors of 3 American women with mysterious symptoms talked together in 1989. However, many people became ill as long as 2â€“3 years before the illness was reported to the Centers for Disease Control and Prevention in November 1989. Rheumatologists experienced a large surge of new patients with mysterious symptoms during this period. It is possible that as many as 60,000 individuals became ill from using L-tryptophan. Additionally, when first marketed, 27 people died.
Some epidemiologist studies traced the cause to consumption of L-tryptophan from a single Japanese manufacturer, Showa Denko. The company supplied the majority of L-tryptophan to the United States under various brand names. There was evidence that new batches of L-tryptophan may have been improperly prepared. First, the specific bacterial culture used to synthesise this tryptophan had recently been genetically engineered to greatly increase tryptophan production. The increased concentrations of tryptophan in the fermentor may in turn have led to increased production of trace impurities. It is also likely that contaminants were increased because the L-Tryptophan producing bacteria were being grown in an open vat in a fertilizer factory. Second, shortcuts had been taken in the purification process to reduce costs. For example, a purification step that used charcoaladsorption to remove impurities had been modified to reduce the amount of charcoal used. It is possible that one or more of these modifications and/or the environment for manufacture allowed new or greater impurities through the purification system. More than 60 different impurities were identified in the L-tryptophan lots which had been associated with cases of EMS.
The specific impurity (or impurities) responsible for the toxic effects was never firmly established, however two compounds, EBT (1,1′-ethylidene-bis-L-tryptophan) and MTCA (1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid), which are close chemical relatives of L-tryptophan were implicated.
Regardless of the origin of the toxicity, L-tryptophan was banned from sale in the US in 1991; and other countries followed suit. In February 2001, the FDA loosened the restrictions on the marketing of tryptophan (though not on importation). The supplement 5-HTP (a hydroxylated form of tryptophan and a precursor to serotonin) remains widely available. …
An alternative explanation for tryptophan associated EMS has recently been proposed. Consumption of large doses of tryptophan leads to production of metabolites, some of which may interfere with normal histamine degradation. Furthermore, excessive histamine activity has been linked with blood eosinophilia and myalgia.
Just to be safe, I’d go for the natural sources:
Pumpkin seeds are a natural source of L-tryptophan, with a tryptophan content of 0.576 grams per 100 grams of dried pumpkin seeds. Roasted pumpkin seeds, with or without added salt, have a slightly lower tryptophan content.
The L-tryptophan content of an egg remains almost the same (cooked as uncooked), 0.166 grams (per 100 grams), when cooked.
Turkey is notoriously known for its tryptophan content, although in fact it contains no more L-tryptophan per 100 grams than any other meat. The popular belief that turkey at Thanksgiving causes sleepiness is a myth; sleepiness after a turkey feast is more likely due to general overeating and alcohol consumption.