5-Hydroxytryptophan for Weight Control
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
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 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.
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.