Krzysztof Mariusz Halczuk, Bolesław Karwowski

Benefits and risks of tryptophan supplementation

 

 

2024-11-20

Introduction. Tryptophan (Trp), discovered in 1901 by Sir Frederick Gowland Hopkins, is one of the eight essential amino acids that must be supplied through the diet. The WHO recommends a daily intake of Trp of 4 mg/kg body weight. It is found in protein-rich foods such as meat, fish, eggs, dairy, nuts, seeds and soy. Trp supports muscle growth, enzyme function and is a precursor to serotonin, melatonin and cinurenin, which affect mood, sleep and immune and inflammatory functions.

Research Objective. The purpose of this study is to present the latest research and observations on the effects of tryptophan on human mental health and mood in order to introduce in an accessible form the benefits and risks of a diet rich/poor in tryptophan in both healthy patients and those struggling with mood disorders.

Material and Methods. To gather material for the study, a review of the scientific literature from the last 10 years was conducted, focusing on original and clinical studies on tryptophan metabolism and its effects on behavior in humans. Results of studies in animal models were also included. PubMed and Web of Science databases were searched using the following keywords: “tryptophan,” “tryptophan metabolism,” “tryptophan and mental health,” “tryptophan and psychiatric diseases,” “serotonin metabolism,” “tryptophan in the diet,” “tryptophan supplementation.” Results were limited to the last 10 years, although older publications were included for key clinical trials or relevant historical data.

Results. Tryptophan plays a key role in mood and sleep regulation as a precursor of serotonin and melatonin. Its metabolites can have neuroprotective (kynurenine) or neurotoxic (quinolinic acid, 3-hydroxy kynurenine) effects, and their disruption can lead to depression. Trp supplementation alleviates symptoms of depression and improves sleep quality, especially in the elderly and those at risk for mood disorders. Attempts to use Trp to treat obesity and type II diabetes have not yielded significant results. Trp appears safe, even in doses much higher than recommended.

Conclusions. Tryptophan supplementation can be helpful in reducing stress, mood disorders and sleep problems, but is not effective in controlling body weight. Based on the literature reviewed, we suggest that the daily dose of tryptophan during supplementation should be 1-3 grams per day in divided doses, as larger amounts do not increase effectiveness. Supplementation should be avoided in patients taking drugs that affect serotonin metabolism, due to the risk of serotonin syndrome.

Keywords: depression, diet, tryptophan, mood, sleep disorders, supplementation.

© Farm Pol, 2024, 80(6): 415–424