Almost all cases for which information was available involved tryptophan manufactured
by Showu Denko, a company that had recently changed both its manufacturing process
and the strain of bacillus used to manufacture tryptophan. Fugh-Berman cautions that
absent testing, tryptophan cannot be presumed to be safe. Lake and Spiegel report one
case of EMS in 5-HTP, for which the contaminant was found. Brown and Gerbarg
respond that prescription tryptophan and 5-HTP dispensed in the United States is free
from contamination, but consumers should be careful about purchasing non-
prescription supplements.
Because of its chemical and biochemical relationship to tryptophan, the safety of 5-HTP
has been questioned. However, excluding the one established contamination case,
according to a 2004 review by Das et al., no definitive case of toxicity had emerged
despite the worldwide usage of 5-HTP for last 20 years, with the possible exception of
one unresolved case of a Canadian woman.^10
According to Iovieno et al., writing in 2010, several other cases of EMS-like syndromes
have since been reported in people taking 5-HTP, but the substance was not analyzed.
According to the Das et al. and Iovieno, et al. reviews, extensive analyses of several
sources of 5-HTP have shown no toxic contaminants similar to those associated with
tryptophan nor the presence of any other significant impurities, with the exception of a
single study that showed very small amount of toxic chemical in 5-HTP in lab analysis.
But the quality control issue remains. Thus, there is some risk of contamination with
both tryptophan and 5-HTP, and consumers should buy these supplements only from
reputable sources.
- DOSAGE: Because the half-life of 5-HTP is just 2-5 hours, it should be taken in divided
dosages throughout the day, at least 20 minutes before meals. The “average” dose of 5 -
HTP cited by Brown et al. is 200 - 300 mg. per day, in divided dosages. Iovieno et al. agree.
Lake and Spiegel recommend a maximum of 150 mg. Brown et al. found that the doses of
5 - HTP used in the reviewed studies ranged from 20 to 3250 mg per day, more often from
