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Testosterone doping can easily be masked with green tea
Last reviewed: 01.07.2025
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Green tea suppresses the excretion of testosterone in the urine, making its ratio with the precursor hormone completely legal from the point of view of anti-doping rules.
An athlete can improve his own results by injecting himself with the hormone testosterone. The World Anti-Doping Agency has known about this for a long time and constantly conducts tests, measuring the level of testosterone and epitestosterone in urine. Epitestosterone is a precursor of testosterone, and if there is little of the precursor in the urine, and a lot of testosterone itself, then this indicates one thing: the hormone was injected artificially. Doctors confirm the use of doping, and the athlete is disqualified.
But testosterone doping, as it turns out, can be easily masked with green tea.
Researchers from Kingston University (UK) have discovered that catechin flavonoids contained in green tea inhibit the activity of the enzyme UDP-glucuronosyltransferase (UGT2B17). This enzyme attaches a glucuronic acid residue to the testosterone molecule, and the hormone, supplied with a glucuronic appendage, is excreted from the body in the urine more quickly. If the enzyme is inhibited, the amount of testosterone in the urine will drop, and the ratio of testosterone to its precursor will become normal.
Catechins are present in green and white tea, but not in black tea. According to scientists, no superdoses are needed: drinking a relatively large cup of green tea is enough to significantly reduce the level of testosterone in the urine. So athletes can easily lock testosterone in the body, receiving all the bonuses from the hormone and not worrying about being caught doping.
The scientists published the results of their experiments in the journal Steroids, and also specifically notified the World Anti-Doping Agency of their discovery. Obviously, now the anti-doping police will have to quickly modify their methods to learn how to detect illegal amounts of testosterone even against the background of green tea.