Supplementation of Eurycoma longifolia Jack Extract for 6 Weeks Does Not Affect Urinary Testosterone: Epitestosterone Ratio, Liver and Renal Functions in Male Recreational Athletes

Background: Eurycoma longifolia Jack (ElJ) has been shown to elevate serum testosterone and increased muscle strength in humans. This study investigated the effects of Physta(®) a standardized water extract of ElJ (400 mg/day for 6 weeks) on testosterone: epitestosterone (T:E) ratio, liver and renal functions in male recreational athletes.

Methods: A total of 13 healthy male recreational athletes were recruited in this double blind, placebo-controlled, cross-over study. The participants were required to consume either 400 mg of ElJ or placebo daily for 6 weeks in the first supplementation regimen. Following a 3 week wash-out period, the participants were requested to consume the other supplement for another 6 weeks. Mid-stream urine samples and blood samples were collected prior to and after 6 weeks of supplementation with either ElJ or placebo. The urine samples were subsequently analyzed for T:E ratio while the blood samples were analyzed for liver and renal functions.

Results: T:E ratio was not significantly different following 6 weeks supplementation of either ElJ or placebo compared with their respective baseline values. Similarly, there were no significant changes in both the liver and renal functions tests following the supplementation of ElJ.

Conclusions: Supplementation of ElJ i.e. Physta(®) at a dosage of 400 mg/day for 6 weeks did not affect the urinary T:E ratio and hence will not breach any doping policies of the International Olympic Committee for administration of exogenous testosterone or its precursor. In addition, the supplementation of ElJ at this dosage and duration was safe as it did adversely affect the liver and renal functions.

Keywords: Doping; Eurycoma longifolia Jack; liver function; renal function; testosterone: epitestosterone ratio.