Tryptophan’s Link To Health

Tryptophan is one of 9 essential amino acids, meaning that it can only be obtained through diet. While only a small amount is needed in the diet, it is important for bodily functions such as mood, sleep, cognition, and behavior.

Tryptophan (Trp) actually changes form once it’s absorbed into the body, converting into 5-HTP, which then turns into serotonin, and then turns into melatonin (known as the “sleep hormone”). It helps both with mood and sleep. Together, these work to regulate the sleep-wake cycle.

Trp and its byproducts are linked to stress, environmental stress, and the body’s ability to respond to stress. After absorption, Trp is involved in many metabolic pathways, and if altered, can disrupt organ systems responsible for keeping the body in balance (homeostasis) including the gut-liver, the neuroendocrine, the immune system, the central nervous system (CNS), and be associated with a variety of metabolic diseases and syndromes. 1

Melatonin’s connection to Tryptophan

Many people when they think of tryptophan, think of Thanksgiving and the turkey that they eat. Ever get sleep after Thanksgiving turkey dinner? It’s likely more about eating too many carbs. According to WebMD, a large meal stimulates the production of insulin, and insulin clears the bloodstream of all amino acids except for tryptophan.

According to the USDA searchable database, white breast roasted turkey has about 309 mg of tryptophan in a 4-ounce serving. Other foods containing significant amounts of tryptophan include milk, cheese, oats, canned tuna, nuts, and seeds.

Trp was studied for its effects on the incidence of metabolic syndrome in a sample of over 7800 individuals. Findings showed that higher dietary intake of Trp improved sleep and reduced the incidence of metabolic syndrome.2

Tryptophan metabolism has also been found to get altered in sleep disorders and it is linked to various neurodegenerative diseases such as Alzheimer’s Disease. Sleep deprivation increases levels of chemicals that are involved in the progression of neurodegenerative diseases.3

Foods for sleep

Supplemental L-Tryptophan

L-Tryptophan supplements have been used to help people with sleep, seasonal affective disorder (SAD), and other conditions. Supplementing with tryptophan may help boost serotonin, known as the “happy hormone” or “feel good hormone” because it can help to relieve anxiety and depression.

A review of Trp highlighted its importance as both a precursor of serotonin and niacin (vitamin B3) and its potential role in managing a number of chronic diseases, such as cardiovascular, kidney, diabetes, cataracts, inflammatory bowel disease, Crohn’s disease, Multiple Sclerosis, and others indicating an urgent need for additional clinical studies designed to investigate the possible therapeutic potential of inexpensive, high-tryptophan foods.4 Supplementation of greater or equal to 1G of Trp has also been found to improve sleep quality.5

A review of research showed that Trp supplementation can improve social behavior in individuals with behavior disorders due to serotonin dysfunction as well as promote social behavior in healthy individuals.6 Another study reviewed 11 randomized clinical trials, concluding that 0.14-3G of tryptophan can be expected to improve the mood of healthy individuals but indicated that further study was needed to determine optimal dosing, delivery method, and schedule.7  

Like a number of other supplements, product quality is key. A recent study identified 9 products tested, and none contained detectable amounts of the tryptophan source. High amounts of unidentified impurities were found in more than half of the supplements. 8


So when you think of tryptophan, know that it is more than a substance found in turkey. While most people do not need to supplement Trp because they get more than enough in their diet, others may benefit from supplementation, especially if they have behavioral, sleep, or cognition issues. While supplementation with Trp has been found to be relatively safe, always consult your healthcare provider prior to supplementing, especially as they can recommend both an appropriate dose and formulation based on your condition.


1.          Palego L, Betti L, Rossi A, Giannaccini G. Tryptophan biochemistry: Structural, nutritional, metabolic, and medical aspects in humans. J Amino Acids. 2016;2016. doi:10.1155/2016/8952520

2.          Wang W, Liu L, Tian Z, Han T, Sun C, Li Y. Dietary Tryptophan and the Risk of Metabolic Syndrome: Total Effect and Mediation Effect of Sleep Duration. Nat Sci Sleep. 2021;13. doi:10.2147/NSS.S337171

3.          Bhat A, Pires AS, Tan V, Babu Chidambaram S, Guillemin GJ. Effects of Sleep Deprivation on the Tryptophan Metabolism. International Journal of Tryptophan Research. 2020;13. doi:10.1177/1178646920970902

4.          Friedman M. Analysis, Nutrition, and Health Benefits of Tryptophan. International Journal of Tryptophan Research. 2018;11. doi:10.1177/1178646918802282

5.          Sutanto CN, Loh WW, Kim JE. The impact of tryptophan supplementation on sleep quality: a systematic review, meta-analysis, and meta-regression. Nutr Rev. 2022;80(2). doi:10.1093/nutrit/nuab027

6.          Steenbergen L, Jongkees BJ, Sellaro R, Colzato LS. Tryptophan supplementation modulates social behavior: A review. Neurosci Biobehav Rev. 2016;64. doi:10.1016/j.neubiorev.2016.02.022

7.          Kikuchi AM, Tanabe A, Iwahori Y. A systematic review of the effect of L-tryptophan supplementation on mood and emotional functioning. J Diet Suppl. 2021;18(3). doi:10.1080/19390211.2020.1746725

8.          Karakawa S, Nakayama A, Ohtsuka N, Sato K, Smriga M. Detection of impurities in dietary supplements containing l-tryptophan. Amino Acids. 2022;54(5). doi:10.1007/s00726-022-03125-9

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