TOKYO--A prospective study published in the March 1 New England Journal of Medicine (344, 9:632-6, 2001) reported that green tea may not prevent gastric cancer as previously believed. According to researchers led by Dr. Takeshi Sano from the National Cancer Center Hospital based here, these results question whether polyphenols in green tea have antimutagenic, anticarcinogenc and anti-inflammatory effects.

In January 1984, approximately 26,000 men and women ages 40 and over in northern Japan were asked to complete a questionnaire that included questions concerning the frequency of green tea consumption. Results were adjusted for sex, age and history of peptic ulcer, smoking and alcohol intake. In a follow-up in the 1990s, researchers identified 419 cases of gastric cancer. It was pointed out that although green tea did not lead to gastric cancer, it did not prevent this sometimes-fatal disease, either.

Gastic cancer is the most common cancer for both men and women in Japan, responsible for almost 20 percent of all cancer-related deaths. In the case of this study, the subjects' gastric cancer was caused by low socioeconomic status and a high-salt diet. From the questionnaires, it was found that drinking five (500 mL) or fewer cups of tea per day did not affect cancer risk. Researchers did note that that the more tea that was consumed, the higher the risk for cancer. However, it was also found that the heavy tea drinkers were also heavy cigarette smokers. "These confounding factors complicate the interpretation of the role of green-tea consumption, even with a multivariate analysis," the researchers stated in an editorial accompanying the study.

In the meantime, large cohort studies and intervention trials are underway in Japan in order to further examine the relationship between green tea and cancer. "In the interim, those who enjoy green tea as a beverage can continue to drink it, but there should be no expectation that this practice will reduce the risk of gastric cancer," the researchers concluded. For more information, visit www.nejm.org.