A recent systematic review from The Cochrane Library summarises all of the published evidence for green tea in preventing cancer.

A systematic review is a rigorous attempt to find, evaluate and combine all of the research on a topic.  The great thing about systematic reviews is that they can, potentially, find a definitive answer to a question, where individual studies often prove inconclusive.

The main limitation of this particular systematic review is its very broad scope, encompassing all types of cancer.  It is questionable whether any summarised answer would be applicable to individual cancer types.

The reviews only found one clinical trial on prostate cancer, and it was focused on men with prostatic intraepithelial neoplasia (PIN).  It found that only one of the men in the study who took green tea went on to develop prostate cancer compared with nine of the men who were in the control group.  In spite of the small samples size (60), this was a statistically significant benefit.

The reviewers concluded:  "The evidence that the consumption of green tea might reduce the risk of cancer was conflicting. This means, that drinking green tea remains unproven in cancer prevention, but appears to be safe at moderate, regular and habitual use."

Links:

• Green tea (Camellia sinensis) for the prevention of cancer (Cochrane Library)
• Information about prostatic intraepithelial neoplasia (PIN) from UK Prostate Link
• Information about preventing prostate cancer from UK Prostate Link