5-Hydroxytryptophan

5-Hydroxytryptophan

5-Hydroxytryptophan or 5-HTP is a naturally-occurring amino acid, a precursor to the neurotransmitter serotonin and an intermediate in tryptophan metabolism. It is marketed in the United States and other countries as a dietary supplement for use as an antidepressant, appetite suppressant, and sleep aid.

Metabolism

5-Hydroxytryptophan is decarboxylated to serotonin (5-hydroxytryptamine or 5-HT) by the enzyme aromatic-L-amino-acid decarboxylase with the help of Vitamin B6.

This reaction occurs both in nervous tissue and in the liver. 5-HTP crosses the blood-brain barrier, while 5-HT does not. Excess 5-HTP, especially when administered with Vitamin B6, is thought to be metabolized and excreted.

Pharmacology

The psychoactive action of 5-HTP is thought to derive from its effect on serotonin synthesis in central nervous system tissue. It is believed that an artificially high supply of 5-HTP causes the brain's serotonin-producing neurons to increase production. Increased serotonin production then leads to increased serotonin release.

Research shows that co-administration with carbidopa greatly increases plasma 5-HTP levels. However, several studies have reported that 5-HTP is effective even without a peripheral decarboxylase inhibitor (e.g. carbidopa). Other studies have indicated the risk of a scleroderma-like condition resulting from the combination of 5-HTP and carbidopa.

As a therapeutic supplement

5-HTP, which is found in minute amounts in certain foods like turkey and cheese, is often sold as an over-the-counter therapeutic supplement. In this case, it is usually sourced from the seeds of Griffonia simplicifolia. 5-HTP in supplement form is typically sold in 50 mg or 100 mg gelatin or vegetarian capsules.

Research

A review article suggests that 5-HTP and other neurotrasmitter precursors might be effective for the treatment of depression.

Current research shows promise in using 5-HTP for treating children with night terrors. After six months of use 83.9% of the children treated with 5-HTP were free from their persistent sleep terrors.

Some persons with fibromyalgia find that 5-HTP improves their symptoms. Fibromyalgia sufferers report improvement in sleep, depression, pain and all major complaints related to fibromyalgia. Studies are continuing to refine dosage and continued use.

It is also used as a prophylactic against chronic daily headache. 5-HTP may also be useful in treatment for migraines, since studies have shown that migraines occur when serotonin levels are low.

Dosage

Most supplement providers recommend 50 mg or 100 mg 5-HTP, one to three times per day. Most clinical studies have tested doses of 200-300 mg/day, although one study tested doses as large as 3250 mg/day. In some clinical studies 5-HTP is administered with carbidopa, which substantially changes 5-HTP's pharmacology. Consumption with other proteins or amino acids will decrease absorption in the digestive tract.

Serotonin syndrome was not observed in several studies that augmented traditional antidepressant therapy with 5-HTP, even though the combination therapy was expected to increase the risk of serotonin syndrome above 5-HTP alone. Some users report high doses (300 mg and over) can produce nausea and vomiting.

See also

References

Further reading

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