The results showed a lower risk associated especially with cancers of the stomach/esophagus and colorectum.
The study by lead author Sarah Nechuta, Ph.D., MPH, assistant professor of Medicine, was published online in advance of the Nov. 1 edition of the American Journal of Clinical Nutrition. Wei Zheng, M.D., Ph.D., MPH, professor of Medicine, chief of the Division of Epidemiology and director of the Vanderbilt Epidemiology Center, was the principal investigator for the study.
Large Population Survey
Researchers surveyed women enrolled in the Shanghai Women’s Health Study. The survey included a population-based of about 75,000 middle-aged and older Chinese women. Most of the Chinese women reported drinking primarily green tea.
“For all digestive system cancers combined, the risk was reduced by 27 percent among women who had been drinking tea regularly for at least 20 years,” said lead author Sarah Nechuta, Ph.D., MPH, assistant professor of Medicine. “For colorectal cancer, risk was reduced by 29 percent among the long-term tea drinkers. These results suggest long-term cumulative exposure may be particularly important.”
Tea contains polyphenols or natural chemicals that include catechins like EGCG and ECG. Catechins have antioxidant properties and may inhibit cancer by reducing DNA damage and blocking tumor cell growth and invasion.
Regular tea drinkers in the study were younger, had higher education, exercised more and consumed more fruits and vegetables. While the researchers adjusted for these factors, they could not rule out an effect from these and other unmeasured lifestyle habits.
Also, the study surveyed only nonsmoking and non drinking Chinese women to minimize the potential influence of these two risk factors on the results for tea consumption and digestive system cancer risk.