5-Hydroxytryptophan
Shaw, K., Turner, J., & Del Mar, C. "Tryptophan and 5-Hydroxytryptophan for Depression." Cochrane Database of Systematic Reviews, 2002.
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Birdsall, T. C. "5-Hydroxytryptophan: A Clinically-Effective Serotonin Precursor." Alternative Medicine Review, 1998.
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Turner, E. H., Loftis, J. M., & Blackwell, A. D. "Serotonin a la Carte: Supplementation with the 5-HT Precursor 5-Hydroxytryptophan." Pharmacology & Therapeutics, 2006.
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Gijsman, H. J., et al. "The Effects of 5-Hydroxytryptophan on Mood and Cognition: A Systematic Review." Psychopharmacology, 2002.
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Fernstrom, J. D. "Effects and Side Effects of 5-Hydroxytryptophan." The Journal of Nutrition, 2012.
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