L-Tryptophan

Tryptophan is an essential amino acid that is needed for protein biosynthesis. It is the raw material used to produce serotonin, melatonin, and niacin. Tryptophan plays a vital role in neuropsychiatric health, immune system health, inflammation regulation, stress responses, gastrointestinal physiology, and anti-oxidant defenses.

Serotonin is an important neurotransmitter that regulates mood, sleep, and appetite. Melatonin is a neuromodulator that controls the body’s circadian rhythm, pain, inflammation, and mood.

Low tryptophan levels can worsen depression, anxiety, cognitive performance, headache, light sensitivity, motion sickness, dizziness, and nausea [Drummond, 2005; Drummond, 2006; Gulaj, 2010; Keegan, 2016; Ramos-Chavez, 2018].

High tryptophan foods include turkey, chicken, pork, fish, milk, beans, nuts, eggs, and oatmeal. Consuming purified tryptophan supplements can increase brain serotonin levels more than just eating foods rich in tryptophan [Wurtman, 1980].

Higher tryptophan intake improve cognitive function, depression, anxiety, and sleep quality [Bravo, 2013; Huang, 2021; Murphy, 2006; Soh, 2011]. Tryptophan supplementation enhances brain serotonin and melatonin levels, which improves mood and sleep quality, respectively [Carneiro, 2018; Fernstron, 2016].

References

Bravo R., Matito S., Cubero J., et al. Tryptophan-enriched cereal intake improves nocturnal sleep, melatonin, serotonin, and total antioxidant capacity levels and mood in elderly. Age 2013;35:1277–1285

Carneiro I.B.C., Toscano A.E., Lacerda D.C., et al. L-tryptophan administration and increase in cerebral serotonin levels: Systemic review. Eur. J. Pharmacol. 2018;836:129–135

Drummond PD. Effect of tryptophan depletion on symptoms of motion sickness in migraineurs. Neurology 2005;65:620-2

Drummond PD. Tryptophan depletion increases nausea, headache, and photophobia in migraine sufferers. Cephalalgia 2006;26:1225-33

Fernstrom J.D. A Perspective on the Safety of Supplemental Tryptophan Based on Its Metabolic Fates. J. Nutr. 2016;146:S2601–S2608

Gulaj E, Pawlak K, Bien B, Pawlak D. Kynurenine and its metabolites in Alzheimer’s disease patients. Adv Med Sci 2010;55:204-11

Huang J, Tong J, Zhang P, et al. Effects of neuroactive metabolites of the tryptophan pathway on working memory and cortical thickness in schizophrenia. Transl Psychiatry 2021;11:198

Keegan MR, Chittiprol S, Letendre SL, et al. Tryptophan metabolism and its relationship with depression and cognitive impairment among HIV-infected individuals. Int J Tryptohan Res 2016;9:79-88

Murphy S.E., Longhitano C., Ayres R.E., et al. Tryptophan supplementation induces a positive bias in the processing of emotional material in healthy female volunteers. Psychopharmacology 2006;187:121–130

Ramos-Chavez LA, Roldan-Roldan G, Garcia-Juarez B, et al. Low serum tryptophan levels as an indicator of global cognitive performance in nondemented women over 50 years of age. Oxid Med Cell Longev 2018;2018:8604718

Soh N.L., Walter G. Tryptophan and depression: Can diet alone be the answer? Acta Neuropsychiatr 2011;23:3–11

Wurtman RJ, Hefti F, Melamed E. Precursor control of neurotransmitter synthesis. Pharmacol Rev 1980;32:315-35