On 2015 Oct 02, Simon Young commented:

This is an interesting review but omits some important manuscripts. For example, in the section on the effect of tryptophan loading on mood in healthy volunteers there is no mention of several relevant studies Leathwood PD, 1982, Charney DS, 1982, Greenwood MH, 1974, SMITH B, 1962. The same is true for studies on the effect of tryptophan on sleep Griffiths WJ, 1972, Hartmann E, 1977, Adam K, 1979. The statement in the section 4.1 that “there is little consensus in terms of Trp’s efficacy in treating depression” is not universally accepted. A Cochrane Database Systematic Review concluded that the available evidence suggests that tryptophan is better than placebo at alleviating depression Shaw K, 2002, and tryptophan has been available as a prescription drug for the treatment of depression in a number of countries. The Cochrane Database Systematic Review includes a number of studies not included in the article.

On 2015 Oct 02, Simon Young commented:

This is an interesting review but omits some important manuscripts. For example, in the section on the effect of tryptophan loading on mood in healthy volunteers there is no mention of several relevant studies Leathwood PD, 1982, Charney DS, 1982, Greenwood MH, 1974, SMITH B, 1962. The same is true for studies on the effect of tryptophan on sleep Griffiths WJ, 1972, Hartmann E, 1977, Adam K, 1979. The statement in the section 4.1 that “there is little consensus in terms of Trp’s efficacy in treating depression” is not universally accepted. A Cochrane Database Systematic Review concluded that the available evidence suggests that tryptophan is better than placebo at alleviating depression Shaw K, 2002, and tryptophan has been available as a prescription drug for the treatment of depression in a number of countries. The Cochrane Database Systematic Review includes a number of studies not included in the article.