The article by Delgado et al1 raises a potentially serious public health problem that was not addressed. Their investigation indicated that administration of a tryptophan-free amino acid mixture to remitted depressed patients led to relapse within 2 to 7 hours in a majority of cases. Unfortunately, this excellent study may be undergoing frequent replication by unknowing subjects.
Tryptophan-free amino acid mixtures are a popular supplement sold in health food stores. All that is required for an unsuspecting person to replicate the experimental protocol is to consume a low tryptophan diet for 1 day before consuming the mixture. While probably few would take as much as in the study, the minimum conditions necessary to induce relapse are unknown. Abrupt return of intense depressive symptoms, as described in this study, might lead a person to discontinue otherwise effective antidepressant treatment or even become suicidal. This latter possibility is of particular concern
Norden M. Risk of Tryptophan Depletion Following Amino Acid Supplementation. Arch Gen Psychiatry. 1993;50(12):1000. doi:10.1001/archpsyc.1993.01820240084010