Effects of 5-hydroxytryptophan on distinct types of depression: A systematic review and meta-analysis

Abstract

Context: Serotonergic dysfunction, including reduced central serotonin levels, is associated with different psychiatric syndromes, including depression. As a serotonin precursor, 5-hydroxytryptophan has long been used as a nonpharmacological treatment for depression. Objective: A systematic review and meta-analysis was conducted to determine the antidepressant effects of 5-hydroxytryptophan in depressed patients. Data sources: MEDLINE (via PubMed) and Google Scholar were searched from inception to May 2018. Data extraction: Thirteen investigations were included in the systematic review (using PRISMA guidelines), and 7 in the full meta-analysis (pre-registered on PROSPERO: CRD42018104415). Da..