CAM Type: biologically based

Common Names: 5-HTP

Introduction to 5-HTP:

5-Hydroxytryptophan is a precursor to the neurotransmitter serotonin and an intermediate in tryptophan metabolism. It is marketed in the US and other countries as a dietary supplement for use as an appetite suppressant, antidepressant and a sleep aid.

5-HTP has been shown useful in some conditions characterized, in part, by serotonin deficits, especially depression. It has also been shown to be useful in some people with insomnia, obesity, chronic tension headache and fibromyalgia.

Intestinal absorption of 5-HTP does not require a transport molecule, and is not affected by the presence of other amino acids; therefore it can be taken with food without reducing its effectiveness. Unlike L-tryptophan, 5-HTP cannot be shunted into niacin or protein production.

CAM therapy practitioners often recommend 5-HTP instead of standard SSRIs or MAOIs, as 5-HTP is believed to accomplish the same goal without resorting to disturbing the brain’s natural metabolic procedures, as many drugs do.

Preparation Methods:

5-HTP is found in infinitesimal amounts in numerous foods like turkey and dairy products, and is often sold as an over-the-counter (OTC) supplement. In this case it is usually derived from the seeds of the Griffonia simplicifolia plant. Production of 5-HTP soared when L-tryptophan, a similar serotonin-altering supplement, was banned in the United States after a tainted batch caused severe adverse effects in users.

Pharmacology:

5-HTP’s psychoactive action is believed to derive from its effect on serotonin synthesis. It is believed that an artificially high level of 5-HTP causes the brain’s serotonin-producing neurons to increase production. Increased serotonin production leads to increased release.

Some clinicians suggest that 5-HTP be administered with a peripheral decarboxylase inhibitor (such as carbidopa) to prevent elevated serotonin levels in the bloodstream (and the subsequent side effects).

Mechanisms of Action:

The mechanism of the possible antidepressant effects of 5-HTP is accounted for by its conversion to the neurotransmitter serotonin which plays a key role in the affective state. Antidepressants may work by either binding to one or more of the 5-HT receptors or by inhibiting serotonin reuptake. Some evidence suggests that 5-HTP has some analgesic activity with fibromyalgia, and in one study, it was found to have some benefits in those with chronic tension headache. This may be accounted for, in part, by its conversion to serotonin.

Safety, Side Effects and Warnings:

5-HTP should not be used by those hypersensitive to any component of a 5-HTP-containing product. It is also contraindicated in people with carcinoid tumors, and during or within 2 weeks after discontinuation of an MAOI.

Large doses of 5-HTP can trigger excess of serotonin formation in tissues other than the target organ and cause significant adverse effects. It should not be used concurrently with any antidepressant, including SSRIS, tricyclics, or MAOIs. Concurrent 5-HTP use with an antidepressant may increase the risk of adverse reactions. 5-HTP should not be used by those with ischemic heart disease, coronary artery spasm, uncontrolled hypertension and any other significant cardiovascular disease.

Some people taking 5-HTP have reported experiencing eosinophilia and eosinophilia-myalgia syndrome (EMS). EMS is similar to that caused by L-tryptophan and was linked to contaminants in 5-HTP’s preparation, rather than 5-HTP itself. Changing the 5-HTP resolved the EMS in one group of patients. In some people taking 5-HTP in conjunction with carbidopa, a scleroderma-like skin condition has been reported.

 Other side effects reported include appetite loss, vomiting, difficulty breathing, diarrhea, and nausea. Neurological side effects, including dilation of the pupils, loss of muscle coordination, blurring of vision and abnormally sensitive reflexes, have been reported in those taking large doses. Cardiac dysrhythmias have also been reported by some.

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