Overview

L-Tryptophan is an essential amino acid that is necessary for making proteins. It is naturally found in red meat, poultry, eggs, and dairy.

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.

Uses & Effectiveness

Possibly Ineffective for

  • Depression. Taking L-tryptophan by mouth doesn't seem to be beneficial in patients with depression. Also, it may increase the risk of side effects of some medications.
There is interest in using L-tryptophan for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.

Side Effects

When taken by mouth: L-tryptophan occurs naturally in many foods, and is consumed as part of the diet. L-tryptophan supplements are possibly safe when taken for up to 3 weeks. L-tryptophan can cause some side effects such as drowsiness, stomach pain, vomiting, diarrhea, headache, blurry vision, and others.

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 and Warnings

When taken by mouth: L-tryptophan occurs naturally in many foods, and is consumed as part of the diet. L-tryptophan supplements are possibly safe when taken for up to 3 weeks. L-tryptophan can cause some side effects such as drowsiness, stomach pain, vomiting, diarrhea, headache, blurry vision, and others.

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.
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.

Interactions

    Major Interaction

    Do not take this combination

  • Sedative medications (CNS depressants) interacts with L-TRYPTOPHAN

    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.

    Moderate Interaction

    Be cautious with this combination

  • Serotonergic drugs interacts with L-TRYPTOPHAN

    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.

Dosing

L-tryptophan supplements have most often been used by adults in doses of 60 mg by mouth daily for 16 weeks. Speak with a healthcare provider to find out what dose might be best for a specific condition.

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.
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