The amino acid 5-hydroxytryptophan, or 5-HTP, remains available despite safety concerns. That's because this precursor of melatonin and serotonin has medical uses including a supplemental role in treating mental retardation. Yet, scientists must conduct more research before the potential of 5-HTP can be realized. In their 2003 book "Dietary Supplements," M. J. Cupp and T. S. Tracy point out that the scientific reports investigating 5-HTP have produced mixed results.
Impairs Decision Making
As a precursor of melatonin, 5-HTP impacts daytime alertness and nighttime sleepiness. A report by M. H. Gendle and A. C. Golding published in the August 2010 edition of the medical journal "Human Psychopharmacology" looked at gambling performance during high risk, and no risk, games. Two comparable groups of college students participated in the study. One set received 5-HTP capsules and the other set received placebo pills. Testing took place soon after a single dose of either substance. Results indicated that 5-HTP intake had no effect when high risk was involved. The amino acid, however, caused bad decisions when no risk was involved. This data is comparable to that found in sleep-deprivation studies. Such experiments typically show that high levels of motivation can overcome large amounts of deprivation.
Causes Drug Interactions
Serotonin plays an important role throughout the human body. Chemicals, therefore, that affect serotonin levels impact many systems and alter other substances. A paper by M. Larson and his co-workers in Copenhagen, Denmark evaluated the concurrent intake of 5-HTP and gaboxadol. The latter drug promotes sleep. This study tested rats following one dose of each substance. A control group received only gaboxadol. The findings, presented in the Jan. 31, 2010 issue of "European Journal of Pharmaceutical Sciences," showed that 5-HTP and gaboxadol interacted. The serotonin precursor first reduced absorption, and then delayed elimination, of the sleeping pill. This data suggests that 5-HTP may interact with other drugs, as well, and such interactions can become dangerous.
Alters Diagnostic Markers
Taking 5-HTP can affect other medical treatments. An investigation by T. Joy and associates published in the January 2008 edition of "Canadian Journal of Gastroenterology" assessed the effect of 5-HTP on the urinary excretion of 5-hydroxyindoleacetic acid, or 5-HIAA. This chemical, used to detect endocrine tumors, plays a role in aggression and suicide. For this experiment, the scientists tested one group of subjects on two different occasions. The patients received either 5-HTP or placebo in a randomized order. The data showed that 5-HTP use enhanced the diagnostic marker. The authors speculated that such increases could be interpreted as signs of a tumor and lead to additional, unwarranted testing. Such procedures would likely cause depression and anxiety in the patients who, unknowingly, received the false report. In addition, the large increases in 5-HIAA observed in this study could cause unknown side effects. The latter notion becomes more likely if such high levels were maintained for extended periods of time due to repeated 5-HTP intake.
References
- "Dietary Supplements"; M. J. Cupp & T. S. Tracy; 2003
- "Human Psychopharmacology"; Oral Administration of 5-Hydroxytryptophan (5-HTP) Impairs Decision Making under Ambiguity but not under Risk: Evidence from the Iowa Gambling Task; M. H. Gendle & A. C. Golding; August 2010
- "European Journal of Pharmaceutical Sciences"; 5-Hydroxy-L-tryptophan Alters Gaboxadol Pharmacokinetics in Rats: Involvement of PAT1 and rOat1 in Gaboxadol Absorption and Elimination; M. Larsen et al.; Jan. 31, 2010
- PubMed.gov: Increase of Urinary 5-Hydroxyindoleacetic Acid Excretion but not Serum Chromogranin A following Over-the-Counter 5-Hydroxytryptophan Intake
- Drugs.com: 5-hydroxytryptophan
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