After taking more than a year to respond to a tea health claim petition as a cancer preventative, the FDA in June 2005 came back with a real stinker of a decision to deny the request and state further that it was “highly unlikely” that tea had any cancer preventive effect. No one expected the FDA to categorically state that tea definitely prevents cancer, but they should have acknowledged by allowing a limited claim that there is substantial evidence of tea’s anti-cancer effect.
The FDA took an excessively hard line by eliminating as evidence research that was done outside the US, and by ignoring high quality studies that had not yet been replicated. In addition, the FDA decided to discount studies done in subjects already having cancer. They also decided not to allow meta-analyses, since they said they could not evaluate the methods of the individual studies upon which those meta-analyses were based (I guess they did not feel like looking up the original studies). They also decided to totally ignore animal and in vitro studies that are crucial to support the believability of human studies. As well they ignored all observational studies, saying that they could not identify the activity of a tea substance (EGCG) mentioned in the petition.
Overall the FDA chose to ignore large bodies of evidence in favor of a health benefit for tea. I cannot speculate as to why they felt they wanted to deprive the American public of its endorsement, but the reason was certainly not based on the preponderance of evidence. To read the FDA’s decision go here.
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