L-tryptophan

L-tryptophan is an amino acid that is used in the biosynthesis of proteins. It is one of the 20 standard amino acids, as well as an essential amino acid in the human diet, meaning that it cannot be synthesized by the human body and must be obtained from the diet. L-tryptophan is encoded by the codon UGG.

Function

L-tryptophan plays several critical roles in the body. It is a precursor to serotonin, a neurotransmitter that is involved in regulating mood, sleep, and appetite. It is also a precursor to melatonin, a hormone that regulates sleep-wake cycles, and to niacin (vitamin B3), which is necessary for the metabolism of food and the maintenance of healthy skin, nerves, and digestion.

Dietary Sources

L-tryptophan is found in most protein-based foods or dietary proteins. It is particularly abundant in chocolate, oats, dried dates, milk, yogurt, cottage cheese, red meat, eggs, fish, poultry, sesame, chickpeas, almonds, sunflower seeds, pumpkin seeds, and peanuts.

Absorption and Metabolism

After ingestion, L-tryptophan is absorbed from the gut and transported to the liver. In the liver, it can be incorporated into proteins or undergo metabolism through several pathways. The most significant pathway involves its conversion into serotonin in the brain, which is a critical step in the synthesis of melatonin.

Health Benefits and Uses

L-tryptophan supplements are often marketed for their potential to improve mood, reduce symptoms of depression, and promote better sleep. However, the effectiveness of L-tryptophan as a supplement for these purposes remains a subject of scientific research and debate.

Safety and Side Effects

Generally, L-tryptophan is considered safe when consumed in food. However, supplements can cause side effects, especially at high doses. These can include nausea, headache, dizziness, and drowsiness. In the late 1980s, a contaminated batch of L-tryptophan supplements was linked to a potentially fatal blood disorder called eosinophilia-myalgia syndrome (EMS). Since then, the safety of L-tryptophan supplements has been improved, but caution is still advised.

Regulatory Status

In the United States, the Food and Drug Administration (FDA) lifted a ban on the sale of L-tryptophan supplements in 2005, but it continues to monitor products on the market for purity and safety.

Conclusion

L-tryptophan is an essential amino acid with important roles in protein synthesis and the production of serotonin and melatonin. While it is generally safe when consumed as part of a balanced diet, the use of supplements should be approached with caution.