5-Hydroxytryptophan (5-HTP) Simply Explained

1. What Is 5-Hydroxytryptophan (5-HTP)?

5-Hydroxytryptophan is an amino acid. The body forms it from L-tryptophan and further converts it to serotonin. Serotonin is a messenger substance that plays a role in mood and sleep, among other things. As a dietary supplement, the substance is usually available as a capsule or tablet. Some preparations are mixtures with other substances, and it is also available as a drug with the name oxitriptan. There are separate studies on L-tryptophan, melatonin, and antidepressants that do not apply to 5-hydroxytryptophan.

2. Where Is It Found, and What Is It Made From?

In nature, 5-hydroxytryptophan is found mainly in the seeds of the West African legume Griffonia simplicifolia. Small amounts also occur in other plants and in animal tissues. For preparations, the substance is obtained from these seeds or produced in the laboratory. In the body, it is continuously formed as an intermediate step in the synthesis of serotonin.

3. What Does 5-Hydroxytryptophan (5-HTP) Do? What Research Shows

Depressed Mood

The findings are best studied in depressed mood. In a first depressive episode, depression scores decreased with 5-hydroxytryptophan as a pure substance 6. In Parkinson's patients with depression, the score improved more than with a placebo 9. In the study on the first depressive episode, the substance did not help better, but similarly well as a known antidepressant 6. The studies are mostly small and short, and such data are lacking for griffonia extract or delayed-release preparations.

Sleep

In older people with poor sleep, the time to fall asleep shortened under 5-hydroxytryptophan as a pure substance compared with people not taking it 10. However, the reported total sleep time decreased in the same study 10. The evidence is limited: the studies are small, short, and tested different forms.

Fibromyalgia

In fibromyalgia, that is persistent pain in muscles and connective tissue, 5-hydroxytryptophan as a pure substance improved the symptoms in a controlled study (with a comparison group) 17. In another study, the combination with another drug helped more than the substance alone 16. The evidence is weak: only one of the two studies tested the substance alone. Data on Griffonia extract, oxitriptan or delayed-release preparations are lacking for this area.

Anxiety

For anxiety, a small study in older people without a placebo group found no effect of 5-hydroxytryptophan as a pure substance 7. Another study reports an improvement in tension-anxiety, but a mixture with other substances was tested there; the result does not apply to 5-hydroxytryptophan alone 5. Overall, there are only a few studies with few participants. Whether the substance alone has any effect on anxiety at all is open.

Appetite and Body Weight

The picture is unclear for appetite and body weight. A combined evaluation of studies on L-tryptophan and 5-hydroxytryptophan found no difference in body mass index 3; nothing can be inferred from this for 5-hydroxytryptophan alone. A spread with several additives did not influence hunger and satiety 15. A single case report cannot be generalized 19, and a review classifies the role of the substance in obesity as unclear 22. Reliable statements on pure substance or Griffonia extract are lacking here.

Other Investigations

In further investigations, very different people and forms were tested. Two small studies in older people without a placebo group found a better score in a cognitive test and more serotonin in the blood under the pure substance 7 and a more favorable gut flora in poor sleepers 8. The authors of the first study advise caution due to the small group 7. The studies are predominantly small, short, and poorly comparable.

4. How Was 5-Hydroxytryptophan (5-HTP) Taken in the Studies?

In the studies, 5-hydroxytryptophan was predominantly taken as a pure substance in capsules or tablets 67891012131417. Sustained-release preparations and oxitriptan as a drug were not tested in the controlled studies on the mentioned areas. Mixed preparations with other substances or with carbidopa say nothing about 5-hydroxytryptophan alone. For each study, form, dose, and duration are important because these details cannot be transferred to other preparations.

5. Is 5-Hydroxytryptophan (5-HTP) Safe? Side Effects in the Studies

The reported side effects were predominantly mild and temporary 1117; fatigue, nausea, or vomiting were also reported 14, as well as, without assignment to a treatment group, mild stomach pain and sleep disturbances 16. In an open case series in which all participants received the substance, almost one third reported side effects. One participant had to discontinue treatment because of this 18. Many studies were small and short, and controlled data are completely lacking for some forms. A measured value in blood or urine is a laboratory finding and not a noticeable effect.

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