Tryptophan is an amino acid needed for normal growth in infants and for the production and maintenance of the body's proteins, muscles, enzymes, and neurotransmitters. It is an essential amino acid. This means your body cannot produce it, so you must get it from your diet.
Function
The body uses tryptophan to help make melatonin and serotonin. Melatonin helps regulate the sleep-wake cycle, and serotonin is thought to help regulate appetite, sleep, mood, and pain.
The liver can also use tryptophan to produce niacin (vitamin B3), which is needed for energy metabolism and DNA production. In order for tryptophan in the diet to be changed into niacin, the body needs to have enough:
- Iron
- Vitamin B2 (Riboflavin)
- Vitamin B6 (Pyridoxine)
Food Sources
Tryptophan can be found in:
- Cheese
- Chicken
- Egg whites
- Fish
- Milk
- Sunflower seeds
- Peanuts
- Pumpkin seeds
- Sesame seeds
- Soy beans
- Turkey
Images
References
Nagai R. Amino acids and proteins. In: Baynes JW, Dominiczak MH, eds. Medical Biochemistry. 6th ed. Philadelphia, PA: Elsevier; 2023:chap 2.
US Department of Agriculture and US Department of Health and Human Services. Dietary Guidelines for Americans, 2025-2030. 10th Edition. January 2026. cdn.realfood.gov/DGA.pdf. Accessed April 20, 2026.
Zuraikat FM, Wood RA, Barragán R, St-Onge MP. Sleep and diet: Mounting evidence of a cyclical relationship. Annu Rev Nutr. 2021; 41:309–332. PMID 34348025 pubmed.ncbi.nlm.nih.gov/34348025/.
Review Date 4/30/2026
Updated by: Stefania Manetti, RDN, CDCES, RYT200, My Vita Sana LLC - Nourish and heal through food, San Jose, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.