Does tea prevent cancer? The evidence isn't there

Over the past decade or so, many claims have been made about the ability of tea to reduce the risk for developing a number of diseases, including cancer. But promising stud-ies in animals haven’t been extended to solid evidence that tea drinking has similar benefits for people.

Evidence from animal studies

The talk of tea as a cancer-fighting food first hit the headlines in the 1990s. According to one early investigator, tea had no equal when it came to achieving “remarkable effects.” Studies in animals showed the positive impact of tea on various tumors. Unfortunately, the same impact has not been seen in people.

The tea bubble burst

In Japan (a big tea-drinking country), a study of 40,000 adults found that people who drank 5 or more cups of green tea a day had death rates from cancer comparable to those of people who drank less than one cup a day.

Studies of specific cancers have shown similarly disappointing results. A host of studies have indicated that indi-viduals who consume the most tea are just as likely to develop colon cancer as those who consume the least.

Tea apparently offers no protection against prostate cancer either. In a study of 19,000 Japanese men, those who drank 5 or more cups of green tea daily were just as likely to die of prostate cancer as men who drank less than one cup daily.

Moreover, according to 13 studies involving more than 160,000 women, tea consumption did not affect breast cancer rates. Heavy consumers of black tea (4 cups or more a day) had suffered the same level of breast cancer as those who drank little tea.

Beyond tea drinking

The quantity of tea used in animal studies may explain the effects found in animals versus the lack of effect in humans. Still, say researchers, the infor-mation gleaned from animal studies may guide development of new drugs. For example, in a study of 42 people, con-centrated chemicals derived from green tea boosted levels of key detoxifying enzymes. This could help protect against cancer-causing substances.

From Nutrition Action Healthletter