What is Tryptophan?

Tryptophan is an amino acid the body uses for many purposes, notably to create the neurotransmitter serotonin.

As a nutritional supplement, it is known primarily for its ability to improve mood and sleep.¹

Because we can’t supplement with serotonin itself, we must rely on serotonin precursors such as tryptophan to increase serotonin in the brain.

Tryptophan is categorized as an essential amino acid because we don’t produce it on our own. It must be obtained through diet or direct oral intake.²

A meta-analysis found that tryptophan plasma levels were decreased in patients with major depressive disorder compared to controls.³

Depression and poor sleep quality are typically connected. A genetic variation related to tryptophan has been identified as possibly playing an important role in the relationship between these conditions.⁴ When tryptophan was given to patients with this genetic variation, they showed significantly improved sleep-quality scores.

A placebo-controlled clinical study found that supplemental tryptophan intake increased positive social interactions with people.⁵ In a randomized crossover study, a diet high in tryptophan improved mood.⁶

Additionally, vitamin B6 assists in the conversion of tryptophan into 5-hydroxytryptophan (5-HTP), which is converted into serotonin in the brain.⁷

Supplemental vitamin B3 may reduce premature conversion of tryptophan in the bloodstream, making more tryptophan available to cross the blood-brain barrier where it converts to serotonin.⁷

In a trial in young adults, taking 100 mg of tryptophan with vitamin B3 and vitamin B6 twice daily between meals for seven days led to a significant improvement in mood in young adults with subclinical depression.⁸

In summary, clinical research shows that increasing tryptophan intake can improve sleep and boost mood.

It is best to consume supplemental tryptophan separately from protein and amino acids. •

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References

1. Fernstrom JD. Effects and side effects associated with the non-nutritional use of tryptophan by humans. J Nutr. 2012 Dec;142(12):2236S-44S.
2. Available at: https://www.ncbi.nlm.nih.gov/books/NBK557845/. Accessed January 5, 2021.
3. Ogawa S, Fujii T, Koga N, et al. Plasma L-tryptophan concentration in major depressive disorder: new data and meta-analysis. J Clin Psychiatry. 2014 Sep;75(9):e906-15.
4. van Dalfsen JH, Markus CR. Interaction between 5-HTTLPR genotype and cognitive stress vulnerability on sleep quality: effects of sub-chronic tryptophan administration. Int J Neuropsychopharmacol. 2015 Feb 2;18(3).
5. Moskowitz DS, Pinard G, Zuroff DC, et al. The effect of tryptophan on social interaction in everyday life: a placebo-controlled study. Neuropsychopharmacology. 2001 Aug;25(2):277-89.
6. Lindseth G, Helland B, Caspers J. The effects of dietary tryptophan on affective disorders. Arch Psychiatr Nurs. 2015 Apr;29(2):102-7.
7. Shabbir F, Patel A, Mattison C, et al. Effect of diet on serotonergic neurotransmission in depression. Neurochem Int. 2013 Feb;62(3):324-9.
8. Tsujita N, Akamatsu Y, Nishida MM, et al. Effect of Tryptophan, Vitamin B6, and Nicotinamide-Containing Supplement Loading between Meals on Mood and Autonomic Nervous System Activity in Young Adults with Subclinical Depression: A Randomized, Double-Blind, and Placebo-Controlled Study. J Nutr Sci Vitaminol (Tokyo). 2019;65(6):507-14.