Последние исследования на молодых людях показали, что Трибулус террестрис не влияет на уровень тестостерона, лютеинизирующего гормона и не воздействует на андрогенные рецепторы мышц.<ref>Neychev VK, & Mitev VI. (2005). "The aphrodisiac herb Tribulus terrestris does not influence the androgen production in young men". Journal of Ethnopharmacology 101 (1-3): 319–23</ref> Также существует исследование, которое показало, что данная добавка бесполезна для увеличения силы и мышечной массы.<ref>Rogerson S, Riches CJ, Jennings C, Weatherby RP, Meir RA, Marshall-Gradisnik SM. (2007). "The Effect of Five Weeks of Tribulus terrestris Supplementation on Muscle Strength and Body Composition During Preseason Training in Elite Rugby League Players". The Journal of Strength & Conditioning Research 21 (2): 348–53</ref> Tribulus terrestrisis a nutritional supplement highly debated regarding its physiological and actual effects on the organism. The main claimed effect is an increase of testosterone anabolic and androgenic action through the activation of endogenous testosterone production. Even if this biological pathway is not entirely proven,T. terrestrisis regularly used by athletes. Recently, the analysis of two female urine samples by GC/C/IRMS (gas chromatography/combustion/isotope-ratio-mass-spectrometry) conclusively revealed the administration of exogenous testosterone or its precursors, even if the testosterone glucuronide/epitestosterone glucuronide (T/E) ratio and steroid marker concentrations were below the cut-off values defined by World Anti-Doping Agency (WADA). To argue against this adverse analytical finding, the athletes recognized having usedT. terrestris in their diet. In order to test this hypothesis, two female volunteers ingested 500 mg of T. terrestris, three times a day and for two consecutive days. All spot urines were collected during 48 h after the first intake. The 13C/12C ratio of ketosteroids was determined by GC/C/IRMS, the T/E ratio and DHEA concentrations were measured by GC/MS and LH concentrations by radioimmunoassay. None of these parameters revealed a significant variation or increased above the WADA cut-off limits. Hence, the short-term treatment withT. terrestrisshowed no impact on the endogenous testosterone metabolism of the two subjects. Results and discussionT. terrestrisis an herbal plant that has been extensively used in Chinese and Indian traditional medicine for the treatment ofvarious disorders [10]. It contains protodioscin, a steroidal saponin, that was found to increase the level of testosterone,dehydroepiandrosterone (DHEA) and luteinizing hormone. Based on significant increase of DHEA sulphate levels in theserum of a patient suffering from erectile dysfunction and treated withT. terrestris, it was hypothezised that protodioscinwas converted into DHEA sulphate into the body[11]. However, well-controlled clinical trial regarding the effect ofDHEA or potential precursor of DHEA are actually missing [12]. DHEA is a steroid precursor of testosterone, produced bothin the free (DHEA) and sulphated form (DHEA-S), with an interconversion equilibrium between both forms. In a study, ithas been shown that about 1.5% DHEA is metabolized into testosterone and that the intake of a single oral dose of DHEAdoes not increase the T/E ratio in a group of nine healthy subjects [13]. Following guidance given by the WADA, athreshold for corrected concentrations of DHEA glucuronide at 100 ng/mL is used for identification of samples containing exogenous DHEA[1]. Beyond GC/C/IRMS analysis for directdetermination of exogenous application of DHEA, theconcentration level of DHEA glucuronide appears to be themost sensitive indirect parameter in the urinary steroid profileto ascertain intake of the substance <ref>Saudan C, Baume N, Emery C, Strahm E, Saugy M. Short term impact of Tribulus terrestris intake on doping control analysis of endogenous steroids. Forensic Science International 178 (2008) e7–e10</ref>