Contamination of nutritional supplements with prohormones

Since 1999, the same time when prohormones were entering the market, nutritional supplements became sporadically "contaminated" with prohormones. "Contamination" in this context signifies that a supplement contains substances which are not declared on the label. As the amount of "contamination" is low, less than 1 per mill of the product, it is assumed that the prohormones are not intentionally added to the supplements but "contamination" may occur due to poor quality control during the production of nutritional supplements and prohormones. Several athletes have been tested in the past with positive results for norandrosterone (main metabolite of nortestosterone and the main metabolite of the prohormones of nortestos-terone such as norandrost-4-ene-3,17-dione and norandrost-4-ene-36,176-diol), where the use of nutritional supplements which were containing low traces of prohormones led to positive results. In such a case the athlete has not intentionally applied a doping substance but the sports federations consider the presence of norandrosterone in the urine sample as a doping offence for which the athlete is fully responsible.

To what extent nutritional supplements may be contaminated has been shown in different studies and by an international study supported by the IOC (Geyer et al. 2003). The latter study investigated 630 different nutritional supplements from 13 countries including the United States, Italy, France, Germany and Great Britain. Out of the 634 samples analysed 94 (14.8%) contained prohormones not declared on the label ("positive supplements"). Of these 94 positive supplements 23 samples (24.5%) contained prohormones of nortestosterone and testosterone, 64 samples (68.1%) only contained prohormones of testosterone, 7 samples (7.5%) only contained prohormones of nortestosterone.

In relation to the total number of products purchased per country most of the positive supplements (84%) originate from companies located in the United States. The positive supplements showed anabolic androgenic steroid concentrations of 0.01 |xg/g up to 190 jxg/g. Excretion studies with application of supplements containing nortestosterone prohormones corresponding to a total uptake of more than 1 |xg resulted in urinary concentrations of the nortestosterone metabolite norandrosterone above the cut-off limit (2 ng/ml urine for male) for several hours (positive doping result). Positive doping tests caused by "contaminated" supplements with prohormones of only testosterone or dihydrotestosterone have not been proved which is explainable by the low amounts of contamination and the applied tests which have to differentiate between endogenous and exogenous origin of testosterone and which will not be influenced by ingestion of low amounts of prohormones or testosterone itself.

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