5-Hydroxytryptophan (5-HTP) is a biochemical compound synthesized in the conversion pathway from the amino acid, tryptophan, to serotonin. Tryptophan undergoes a chemical reaction known as hydroxylation, whereby a hydroxyl group is added, resulting in the product, 5-hydroxytryptophan (5-HTP). This reaction is catalyzed by the enzyme hydroxylase. Hydroxylase is also coupled in the conversion of tetrahydrobiopterin to dihydrobiopterin, aiding in the release of one molecule of water.

5-HTP undergoes its conversion to serotonin via the chemical reaction, decarboxylation. It is catalyzed by a decarboxylase enzyme, thereby releasing one molecule of carbon dioxide. [1] Conversion of 5-HTP to serotonin is greater than that of Tryptophan to serotonin. Actually, over 70% of 5-HTP is converted to serotonin, while only 3% of tryptophan results in serotonin production. [2] However, tryptophan remains important, serving as a precursor to other significant biochemical compounds.

Interest in 5-HTP is primarily linked to its effect on serotonin production. Serotonin is also called 5-hydroxytryptamine and is widely recognized as one of the most critical neurotransmitters in human physiology. Neurotransmitters are chemicals that transmit impulses from one neuron (nerve cell) to another. The largest amount of serotonin is actually found in the cells of the intestinal mucosa. Other sites where serotonin exists are the platelets and other areas of the central nervous system. Serotonin is important for regulation of blood pressure, respiration, and mental/emotional function.

Contrary to popular belief, tryptophan and 5-HTP are not interchangeable when taken as a dietary supplement. Unlike tryptophan, 5-HTP is not a precursor to niacin (vitamin B3) and picolinic acid. Furthermore, 5-HTP does not cross the blood brain barrier very readily because it cannot be converted to kynurenine, like tryptophan. Kynurenine is a biochemical compound that is formed when tryptophan is acted on by the enzyme, tryptophan oxygenase.

It is worthy to mention a controversy regarding L-tryptophan which occurred in 1989. Some people may confuse this with 5-HTP because of their chemical similarity, however it had nothing to do with 5-HTP. A contaminated batch of L-tryptophan supplements entered the marketplace from a manufacturing facility in Japan. [3] A number of consumers became ill and 38 people died from a disorder called eosinophilia-myalgia syndrome (EMS). The causative agent was not L-tryptophan itself, but from a particular strain of bacteria that was used to synthesize L-tryptophan. Following this unfortunate incident, L-tryptophan-containing supplements were banned in the United States. It was not until 1996 that the ban was partially lifted, allowing only physicians prescribe the synthetic supplement.

The contamination problem that were associated with L-tryptophan did not apply to 5-HTP-containing products.

Products Containing 5-HTP
Name Price Rating Serving Price # of Servings Manufacturer Health Condition
Amoryn $27.89
$0.46 60 BioNeurix Corporation
Moderex Gaba $27.00
$0.90 30 Progressive Health
Neu-Becalmd $37.50
$0.42 90 Neurogenesis ADHD


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