5-Hydroxytryptophan for Weight Control

Also known as: 5-HTP

What is it?

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 gastro-intestinal 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 a few over-the-counter 5-HTP preparations. Some researchers think this substance may be linked² ³ ⁴ to toxicity previously reported⁵ ⁶ ⁷ 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.⁸ ⁹ ¹⁰ ¹¹ ¹² ¹³ ¹⁴ ¹⁵ Although two articles reported possible associations between 5-HTP consumption and toxicity symptoms similar to those attributed to contaminated L-tryprophan,¹⁶ ¹⁷ 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 diarrhoea 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 auto-immune 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.

Resources

See a list of books, periodicals, and other resources for this and related topics.

*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

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.

10. Reinauer S, Plewig G. [Eosinophilia-myalgia syndrome]. Hautarzt 1991;42(3):137–9 [in German].

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.

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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 chemist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires September 2008.

2007-09-01

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