What is it?
L-tryptophan is important for many organs in the body. L-tryptophan is not made by the body and must be consumed from the diet. After absorbing L-tryptophan from food, the body converts some of it to 5-HTP and then to serotonin. Serotonin is a hormone that transmits signals between nerve cells. Changes in serotonin levels in the brain can affect mood.
People use L-tryptophan for severe PMS symptoms, depression, insomnia, and many other conditions, but there is no good scientific evidence to support any of these uses.
How effective is it?
Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
The effectiveness ratings for L-TRYPTOPHAN are as follows:
Possibly ineffective for...
- Teeth grinding (bruxism). Taking L-tryptophan by mouth doesn't help reduce nighttime teeth grinding.
How does it work?
Are there safety concerns?
In 1989, L-tryptophan was linked to cases of a neurological condition called eosinophilia-myalgia syndrome (EMS). But these cases might be due to contamination. About 95% of all EMS cases have been traced to L-tryptophan produced by a single manufacturer in Japan.
There isn't enough reliable information to know if L-tryptophan is safe when taken for more than 3 weeks.
Special precautions & warnings:Pregnancy: It is possibly unsafe to take L-tryptophan in amounts greater than those found in foods during pregnancy. It might harm the unborn child.
Breast-feeding: There isn't enough reliable information to know if L-tryptophan is safe to use when breast-feeding. Stay on the safe side and stick to food amounts.
Are there interactions with medications?
- Sedative medications (CNS depressants)
- L-tryptophan might cause sleepiness and slowed breathing. Some medications, called sedatives, can also cause sleepiness and slowed breathing. Taking L-tryptophan with sedative medications might cause breathing problems and/or too much sleepiness.
- Serotonergic drugs
- L-tryptophan might increase a brain chemical called serotonin. Some medications also have this effect. Taking L-tryptophan along with these medications might increase serotonin too much. This might cause serious side effects including heart problems, seizures, and vomiting.
Are there interactions with herbs and supplements?
- Herbs and supplements with sedative properties
- L-tryptophan might cause sleepiness and slowed breathing. Taking it along with other supplements with similar effects might cause too much sleepiness and/or slowed breathing in some people. Examples of supplements with this effect include hops, kava, melatonin, and valerian.
- Herbs and supplements with serotonergic properties
- L-tryptophan increases a brain chemical called serotonin. Taking it along with other supplements that have this effect might cause serious side effects, including heart problems, seizures, and vomiting. Examples of supplements with this effect include 5-HTP, black seed, SAMe, and St. John's wort.
Are there interactions with foods?
- There are no known interactions with foods.
What dose is used?
Keep in mind that some dietary supplement products might not list L-tryptophan separately on the label. Instead, it might be listed under niacin. Niacin is measured in niacin equivalents (NE). 60 mg of L-tryptophan is the same as 1 mg NE.
To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.
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