Impact of Tribulus terrestris supplementation on urinary steroid profiles: A short term pilot study

Steroid metabolism is a complex biochemical process susceptible to modulation by exogenous compounds. Tribulus terrestris (TT) is a widely used herbal supplement marketed for its purported ergogenic and anabolic effects. This preliminary investigation aimed to assess the impact of short-term TT supplementation on urinary steroid profiles. Urine samples were obtained over a two-month period from eight male and seven female recreational athletes declaring to daily consume a TT extract. 5α-androstane-3α,17β-diol, 5β-androstane-3α,17β-diol, androsterone, etiocholanolone, 11β-hydroxyandrosterone, 11β-hydroxyetiocholanolone, dihidrotestosterone, 5alpha-Androstane-3,17-dione, epitestosterone, testosterone, 4-androstene-3,17-dione concentrations, along with metabolic ratios, were quantified using a validated gas chromatography–tandem mass spectrometry (GC–MS/MS) methodology. In male recreational athletes, time-dependent increases in 4-androstene-3,17-dione, epitestosterone and testosterone were observed; however, no statistically significant differences were detected between urine samples collected before and during TT extract supplementation. In female participants, an initial increase followed by a subsequent decrease in all measured steroid profile markers was detected, but similarly to the male cohort, no statistically significant differences were identified between samples collected before and during TT supplementation. Despite considerable inter-individual variability in urinary steroid concentrations, no statistically significant alterations in steroid profiles and ratios were observed pre-versus post-supplementation. Although derived from a small sample size, these pilot data suggest that short–term TT supplementation does not elicit measurable changes in urinary steroid hormone profiles under the conditions of this study and is unlikely to interfere with endogenous steroid hormones turnover. Consequently, these findings raise questions the efficacy of TT as a performance-enhancing agent and underscore the necessity for further mechanistic studies on a broader cohort of TT consumers for a larger period of time.