Tryptophan is an essential amino acid found in some foods and dietary supplements. Tryptophan can be converted into 5-HTP in the body; however, supplementing with 5-HTP directly is more reliable for increasing serotonin levels.
The conversion of tryptophan to 5-HTP is the rate-limiting step for the synthesis of both serotonin and melatonin. This means that the speed with which the body can produce serotonin or melatonin relies on how quickly tryptophan can be converted to 5-HTP. When supplementing with 5-HTP, this rate-limiting step is bypassed.[1]
Several factors can limit the conversion of tryptophan to 5-HTP. For one, tryptophan has many different fates within the body (such as protein synthesis), meaning only a small fraction is converted to 5-HTP and subsequently serotonin. However, 5-HTP has the sole purpose of serotonin synthesis. Furthermore, tryptophan has to compete with other amino acids for entry into the brain, while 5-HTP can passively enter the brain without challenge.[2][3][4]
References
- ^Maffei ME5-Hydroxytryptophan (5-HTP): Natural Occurrence, Analysis, Biosynthesis, Biotechnology, Physiology and Toxicology.Int J Mol Sci.(2020-Dec-26)
- ^Javelle F, Lampit A, Bloch W, Häussermann P, Johnson SL, Zimmer PEffects of 5-hydroxytryptophan on distinct types of depression: a systematic review and meta-analysis.Nutr Rev.(2020 Jan 1)
- ^Yousefzadeh F, Sahebolzamani E, Sadri A, Mortezaei A, Aqamolaei A, Mortazavi SH, Shalbafan MR, Ghaffari S, Alikhani R, Mousavi SB, Naderi S, Shamabadi A, Jalilevand S, Akhondzadeh S5-Hydroxytryptophan as adjuvant therapy in treatment of moderate to severe obsessive-compulsive disorder: a double-blind randomized trial with placebo control.Int Clin Psychopharmacol.(2020 Sep)
- ^Birdsall TC5-Hydroxytryptophan: a clinically-effective serotonin precursor.Altern Med Rev.(1998-Aug)