L-tryptophan explained: what it is and food sources
Tryptophan is an essential amino acid that must come from food because your body cannot make it. The NIH says it is needed for making and maintaining the body's proteins, muscles, enzymes and neurotransmitters, and food sources include turkey, chicken, fish, milk, cheese, egg whites, peanuts and pumpkin seeds. Four products we reviewed list L-tryptophan, and none prints its individual amount.
- What it is
- Amino acid
- In the products we reviewed
- 4, none prints the amount
What L-tryptophan is
- Tryptophan is an essential amino acid, so the body cannot make it and it must come from food.1
- Tryptophan is an amino acid needed for normal growth in infants and for making and maintaining the body's proteins, muscles, enzymes and neurotransmitters.1
- The body uses tryptophan to help make melatonin, which helps regulate the sleep-wake cycle, and serotonin.1
- The liver can use tryptophan to make niacin (vitamin B3), which is needed for energy metabolism and DNA production.1
- To change tryptophan into niacin, the body needs enough iron, vitamin B2 and vitamin B6.1
- Foods with tryptophan include cheese, chicken, egg whites, fish, milk, sunflower, pumpkin and sesame seeds, peanuts, soy beans and turkey.1
Foods that have it1
- Turkey
- Chicken
- Fish
- Milk
- Cheese
- Egg whites
- Peanuts
- Pumpkin seeds
How much L-tryptophan each product gives
Amount not printed: the dashed line shows the most it can be, the whole blend
Before you take it
If you take medicines
Ask a doctor first
- L-tryptophan supplements were stopped in 1989 after an outbreak of eosinophilia-myalgia syndrome traced to contaminated L-tryptophan from a single manufacturer.3
These statements have not been evaluated by the FDA. A supplement is not a medicine.
The 4 products we reviewed that list L-tryptophan
| Product | Form and serving | L-tryptophan per serving | Our score | Price a bottle | Buy |
|---|---|---|---|---|---|
 GlucoTonic#1 in blood sugar support | Liquid drops1 ml | Not printedIn a 200 mg proprietary blend | 9.9 | $49 | Check price |
 Sugar Defender#3 in blood sugar support | Liquid drops1 ml | Not printedIn a 200 mg proprietary blend | 9.5 | $49 | Check price |
 Glyco Harmony#5 in blood sugar support | Liquid drops1 ml | Not printedIn a 200 mg proprietary blend | 9.3 | $49 | Check price |
 SeroBurn#3 in weight loss support | Capsules2 capsules | Not printedIn a 843.5 mg proprietary blend | 9.3 | $49 | Check price |
Questions people ask
Is L-tryptophan an essential amino acid?
Yes, tryptophan is an essential amino acid, so your body cannot make it and it must come from food. The NIH says it is needed for making and maintaining the body's proteins, muscles, enzymes and neurotransmitters.
Which foods contain tryptophan?
Turkey, chicken, fish, milk, cheese, egg whites, peanuts and pumpkin seeds contain tryptophan. The NIH also lists sunflower seeds, sesame seeds and soy beans.
How are L-tryptophan and melatonin related?
The body uses tryptophan to help make melatonin, according to the NIH. It also uses tryptophan to help make serotonin.
How are tryptophan and niacin related?
The liver can use tryptophan to make niacin, also called vitamin B3, which is needed for energy metabolism and DNA production. The body needs enough iron, vitamin B2 and vitamin B6 to turn tryptophan into niacin.
Is L-tryptophan safe to take?
Ask a clinician before starting an L-tryptophan supplement. L-tryptophan supplements were stopped in 1989 after an outbreak traced to contaminated L-tryptophan from a single manufacturer.
Which supplements we reviewed contain L-tryptophan?
GlucoTonic, Sugar Defender, Glyco Harmony and SeroBurn list L-tryptophan, but none prints its individual amount. The first three include it in a 200 mg proprietary blend per 1 ml serving. SeroBurn includes it in an 843.5 mg proprietary blend per serving of 2 capsules.
Also in these products
- ChromiumIn 4 of the same products
- Green tea extractIn 4 of the same products
- African mangoIn 3 of the same products
- AstragalusIn 3 of the same products
- Beta-alanineIn 3 of the same products
- Cayenne pepper (capsicum)In 3 of the same products
- Coleus forskohliiIn 3 of the same products
- EleutheroIn 3 of the same products
Sources
The products, amounts and prices come from each product's label and checkout, as its review shows them. AI drafts our pages from listed sources, figures are checked against them, and we have not tried the products.
- 1NIH National Library of Medicine, MedlinePlus, Medical Encyclopedia: Tryptophanmedlineplus.gov/encychecked
- 2NIH Office of Dietary Supplements, Niacin Fact Sheet for Health Professionalsods.od.nih.gov/factsheetschecked
- 3NIH National Center for Complementary and Integrative Health, Sleep Disorders and Complementary Health Approaches: Usefulness and Safetynccih.nih.gov/healthchecked