Tryptofan

Tryptofan, also known as L-tryptophan, is an essential amino acid required for protein synthesis in humans and many other organisms. It cannot be produced in sufficient amounts by the human body and must be obtained from the diet. In addition to its role as a building block for proteins, tryptofan is a precursor to several important biomolecules, including serotonin, melatonin, and niacin (via the kynurenine pathway).

Dietary sources of tryptofan include both animal products—such as poultry, eggs, dairy, and fish—and plant-based foods like soy, seeds, nuts, oats, and legumes. After absorption, tryptofan competes with other large neutral amino acids for transport across the blood-brain barrier, influencing brain serotonin synthesis and, consequently, mood and sleep.

Metabolically, tryptofan follows two major routes. One pathway converts it to serotonin through intermediate 5-hydroxytryptophan, with serotonin potentially being transformed into melatonin in the pineal gland to regulate circadian rhythms. The other principal route is the kynurenine pathway, which ultimately contributes to the production of niacin and other metabolites that participate in immune and nervous system functions.

Safety and regulation: Tryptofan supplements have been associated with eosinophilia-myalgia syndrome in the past, linked to contamination in a specific manufacture batch. Regulatory oversight and quality control have reduced the risk, though it remains important to use reputable products. Interactions with monoamine oxidase inhibitors or other serotonergic medications can raise serotonin levels and, in rare cases, risk serotonin syndrome. As with all supplements, medical advice is advised, particularly during pregnancy, lactation, or for individuals with medical conditions or concurrent medications.