The effect of tea consumption on the steroid profile.

Green tea (GT), along with its flavonol epigallocatechin-3-gallate (EGCG), has shown to inhibit the UGT2B17 isoenzyme, which is highly involved in the glucuronidation of testosterone (T) and its metabolites. Since the steroid profile (SP) is composed of urinary concentrations of T and related metabolites excreted in both the free and the glucuronide fractions, GT consumption could alter the SP, leading to misunderstanding in doping controls. The aim of the present work was to study the effect of GT consumption on the SP. This study was performed with 29 male volunteers, which could be classified in 2 arms depending on their T/E values (0.12 ± 0.02, n = 12; 1.64 ± 0.90, n = 17). The clinical protocol was designed to evaluate the effect of GT administration on the SP biomarkers. Participants were asked to consume GT with a high content of EGCG for 7 days (5 GT beverages along the whole day for days 1-6 and 9 GT beverages on day 7, corresponding to 520 and 936 mg/day of EGCG, respectively). Urine samples were collected before and during GT consumption at different time periods. The SP was measured using gas chromatography-mass spectrometry. The excretion rates of the SP metabolites did not change after GT consumption. Moreover, the individual evaluation of the subject's steroidal biological passport resulted in normal sequences. The results obtained show that GT consumption does not distort the establishment of normal ranges of SP parameters. Therefore, GT consumption does not need to be considered a confounding factor in the SP evaluation.