5-HTP is used by the human body to make serotonin, an important substance for normal nerve
and brain function. Serotonin appears to play significant roles in sleep, emotional moods,
pain control, inflammation, intestinal peristalsis, and other body functions.1
Where is it found?
5-HTP is not present in significant amounts in a typical diet. The human body manufactures
5-HTP from L-tryptophan, a natural amino acid
found in most dietary proteins. However, eating food that contains L-tryptophan does not
significantly increase 5-HTP levels. Supplemental 5-HTP is naturally derived from the seeds of
Griffonia simplicifolia, a West African medicinal plant.
Why do dieters use it?*
Some dieters say that 5-HTP
helps suppress appetite.
helps promote weight loss.
What do the advocates say?*
Known for its ability to promote weight loss, 5-HTP has been shown to reduce appetite. It
appears to do this by stimulating serotonin production in the brain. While 5-HTP has not yet
been extensively researched, some human and double-blind studies have shown that 5-HTP
promotes weight loss.
How much is usually taken by dieters?
Appetite reduction and weight loss (averaging 11 pounds in 12 weeks) has occurred with
amounts of 600 to 900 mg daily. In another clinical trial, 750 mg per day has been shown to be
effective at decreasing carbohydrate and fat intake and promoting weight loss.
Are there any side effects or interactions?
During the clinical trials described above, some people taking large amounts of 5-HTP
experienced gastrointestinal upset (e.g. nausea) or, less often, headache, sleepiness, muscle
pain, or anxiety.
A substance known as “Peak X” has been found in low concentrations in several
over-the-counter 5-HTP preparations. Some researchers think this substance may be
linked234 to toxicity previously reported5
67 in a 1989 L-tryptophan contamination incident. However, there is serious
question about whether Peak X is actually the toxic agent and it may be unrelated to the
problems previously associated with L-tryptophan.8910
1112131415 Although two articles
reported possible associations between 5-HTP consumption and toxicity symptoms similar to
those attributed to contaminated L-tryprophan,1617 evidence linking
5-HTP or Peak X with any toxicity symptoms remains speculative. Although the structure of Peak
X has recently been identified, there is no firm evidence that this substance has caused or
contributed to any toxicity or disease.18
Very high intakes of 5-HTP have caused muscle jerks in guinea pigs19 and both
muscle jerks20 and diarrhea in mice.21 Injected 5-HTP has also caused
kidney damage in rats.22 To date, these problems have not been reported in humans.
“Serotonin syndrome,” a serious but uncommon condition caused by excessive amounts
of serotonin, has not been reported to result from supplementation with 5-HTP; in theory it
could be triggered by the supplement.23 However, the level of intake at which this
toxic effect might potentially occur remains unknown.
5-HTP should not be taken with
antidepressants, weight-control drugs, other serotonin-modifying agents, or substances
known to cause liver damage, because in these cases 5-HTP may have excessive effects. People
with liver disease may not be able to regulate 5-HTP adequately and those suffering from
autoimmune diseases such as scleroderma may be more sensitive than others, to
5-HTP.24 These people should not take 5-HTP without consulting a knowledgeable
healthcare professional. The safety of taking 5-HTP during pregnancy and breast-feeding is not known at this
time.
Are there any drug
interactions?
Certain medicines may interact with 5-hydroxytryptophan. Refer to drug interactions for a list of those medicines.
*Dieters and weight-management advocates may claim benefits for 5-HTP
based on their personal or professional experience. These are individual opinions and
testimonials that may or may not be supported by controlled clinical studies or published
scientific articles on 5-HTP. For more complete and detailed information, including references
and safety information, see 5-HTP as a nutritional
supplement.
References (To view, roll mouse over the "References" heading; to hide, click on the heading)
1. Guyton AC, Hall JE. Textbook of Medical Physiology, 9th ed.
Philadelphia: W. B. Saunders, 1996.
2. Williamson BL, Benson LM, Tomlinson AJ, et al. On-line HPLC-tandem
mass spectrometry analysis of contaminants of L-tryptophan associated with the onset of the
eosinophilia-myalgia syndrome. Toxicol Lett 1997;92:139–48.
3. Williamson BL, Klarskov K, Tomlinson AJ, et al. Problems with
over-the-counter 5-hydroxy-L-tryptophan. Nat Med 1998;4:983.
4. Williamson BL, Tomlinson AJ, Mishra PK, et al. Structural
characterization of contaminants found in commercial preparations of melatonin: similarities
to case-related compounds from L-tryptophan associated with eosinophilia-myalgia syndrome.
Chem Res Toxicol 1998;11:234–40.
5. Belongia EA, Hedberg CW, Gleich GJ, et al. An investigation of the
cause of the eosinophilia-myalgia syndrome associated with tryptophan use. N Engl J
Med 1990;323:357–65.
6. Martin RW, Duffy J, Engel AG, et al. The clinical spectrum of the
eosinophilia-myalgia syndrome associated with L-tryptophan ingestion. Clinical features in 20
patients and aspects of pathophysiology. Ann Intern Med 1990;113:124–34.
7. Mayeno AN, Lin F, Foote CS, et al. Characterization of “peak
E,” a novel amino acid associated with eosinophilia-myalgia syndrome. Science
1990;250:1707–8.
8. Belongia EA, Hedberg CW, Gleich GJ, et al. An investigation of the
cause of the eosinophilia-myalgia syndrome associated with tryptophan use. N Engl J
Med 1990;323:357–65.
9. Mayeno AN, Lin F, Foote CS, et al. Characterization of “peak
E,” a novel amino acid associated with eosinophilia-myalgia syndrome. Science
1990;250:1707–8.
11. Toyo’oka T, Yamazaki T, Tanimoto T, et al. Characterization of
contaminants in EMS-associated L-tryptophan samples by high-performance liquid chromatography.
Chem Pharm Bull (Tokyo) 1991;39(3):820–2.
12. Trucksess MW, Thomas FS, Page SW. High-performance liquid
chromatographic determination of 1,1’-ethylidenebis(L-tryptophan) in L-tryptophan
preparations. J Pharm Sci 1994;83(5):720–2.
13. Trucksess MW. Separation and isolation of trace impurities in
L-tryptophan by high-performance liquid chromatography. J Chromatogr
1993;630(1–2):147–50.
14. Ito J, Hosaki Y, Torigoe Y, Sakimoto K. Identification of substances
formed by decomposition of peak E substance in tryptophan. Food Chem Toxicol
1992;30(1):71–81.
15. Castot A, Bidault I, Bournerias I, et al.
[“Eosinophilia-myalgia” syndrome due to L-tryptophan containing products.
Cooperative evaluation of French Regional Centers of Pharmacovigilance. Analysis of 24 cases].
Therapie 1991;46(5):355–65 [in French].
16. Michelson D, Page SW, Casey R, et al. An eosinophilia-myalgia
syndrome related disorder associated with exposure to L-5-hydroxytryptophan. J
Rheumatol 1994;21:2261–5.
17. Sternberg EM, Van Woert MH, Young SN, et al. Development of a
scleroderma-like illness during therapy with L-5-hydroxytryptophan and carbidopa. N Engl J
Med 1980;303(14):782–7.
18. Johnson KL, Klarskov K, Benson LM, et al. Presence of peak X and
related compounds: the reported contaminant in case related 5-Hydroxy-L-tryptophan associated
with eosinophilia-myalgia syndrome. J Rheumatol 1999;26(12):2714–7.
19. Hagan JJ, Hatcher JP, Slade PD. The role of 5-HT1D and 5-HT1A
receptors in mediating 5-hydroxytryptophan induced myoclonic jerks in guinea pigs. Eur J
Pharmacol 1995;294:743–51.
20. Green AR, Johnson P, Mountford JA, Nimgaonkar VL. Some anticonvulsant
drugs alter monoamine mediated behaviour in mice in ways similar to electroconvulsive shock;
implications for antidepressant therapy. Br J Pharmacol 1985;84:337–46.
21. Bourin M, Hascoet M, Deguiral P. 5-HTP induced diarrhea as a
carcinoid syndrome model in mice? Fundam Clin Pharmacol 1996;10:450–7.
22. Hirai M, Nakajima T. Biochemical studies on the mechanism of
difference in the renal toxicity of 5-hydroxy-L-tryptophan between Sprague Dawley and Wistar
rats. J Biochem (Tokyo) 1979;86:907–13.
23. Martin TG. Serotonin syndrome. Ann Emerg Med
1996;28:520–6.
24. Sternberg EM, Van Woert MH, Young SN, et al. Development of a
scleroderma-like illness during therapy with L-5-hydroxytryptophan and carbidopa. N Engl J
Med 1980;303:782–7.
The information presented in Healthnotes is for informational purposes
only. It is based on scientific studies (human, animal, or in vitro), clinical
experience, or traditional usage as cited in each article. The results reported may not
necessarily occur in all individuals. For many of the conditions discussed, treatment with
prescription or over the counter medication is also available. Consult your doctor,
practitioner, and/or pharmacist for any health problem and before using any supplements or
before making any changes in prescribed medications. Information expires June 2009.
