Are tryptophan and 5-hydroxytryptophan effective treatments for depression?
Shaw K; Turner J; Del Mar C School of Population Health, Department of Public Health, University of Queensland Medical School, Herston 4006, Australia. k.shaw@sph.uq.edu.au OBJECTIVE: To review the literature regarding the effectiveness of 5-hydroxytryptophan (5-HT) and L-tryptophan in the treatment of unipolar depression. METHODS: A systematic review of the literature from 1966 to 2000 using the search terms ‘tryptophan’, 5-hydroxytryptophan’, ‘5-HTP’, ‘5-HT’ and ‘depression’. We extracted and grouped data for meta-analysis by pooling odds ratios (OR) and relative risks where possible. RESULTS: One hundred and eight studies were located of which only two studies, one of 5-HT and one of L-tryptophan, with a total of 64 patients met sufficient quality criteria to be included. These studies suggest 5-HT and L-tryptophan are better than placebo at alleviating depression (Peto OR = 4.1, 95% CI = 1.3-13.2). However, the small size of the studies, and the large number of inadmissible, poorly
