Scientists discovered that green tea can help mask the levels of testosterone in the body.
The study found extracts contained in the beverage, reduced concentrations of the hormone by up to 30%.
Olympic doping officials have now raised concerns that athletes could use tea to hide increased levels of testosterone from standard drugs tests.
Testosterone is one of the oldest illegal steroids used in sports, and it is commonly used to build muscle.
Experts say athletes taking testosterone for doping purposes typically have 200 to 300% more in their bodies than normal.
During the study, researchers added green and white tea extracts – or catechins – to the hormone and discovered that they reduced the concentration by almost a third.
The recent anomaly could now lead to a change in the tests ahead of London Olympics 2012.
Olivier Rabin, scientific director of the World Anti-Doping Agency, or WADA said: “It’s interesting that something as common as tea could have a significant influence on the steroid profile.
“We may need to adjust our steroid (test) to allow us to exclude whether a test is modified by food or training or disease, before we can say that it’s doping.”
The study was conducted in a laboratory so scientists said it was too early to tell what the effect of green tea might be in humans, but similar results have been found in rodent studies.
Other foods and beverages, such as alcohol, are also known to muddle test results and WADA has tight controls on other commonly consumed substances like caffeine.
“There’s no reason to think we just happened to pick the only food in the world that does this,” said Declan Naughton of Kingston University, who published the findings in the journal, Steroids.
Charles Yesalis, a doping expert at Pennsylvania State University, said officials needed to react quickly.
“Athletes will not wait for the clinical trials,” Charles Yesalis said.
“I’ll bet there are already lots of athletes out there drinking loads of green tea,” he added.
However, some experts said the limited effects of foods like green tea on masking illegal drug use would be too small to help doping athletes.
“You would probably need to drink the tea continuously to get any sustained but minor effect,” said Andrew Kicman, head of research and development at the Drug Control Centre at King’s College London, which is providing the anti-doping laboratory for the upcoming Olympics.
“It would be a very foolish athlete who’s thinking of doping with testosterone and thinks he could drink white or green tea to beat a drug test,” he said.
“And I personally wouldn’t want to drink nine cups of tea on the day of a race.”
