Regularly drinking antioxidant-rich green tea may halve the risk of colon and rectal cancer, suggests a new study based in China.
The results add to an ever-growing body of science linking consumption to a wide range of health benefits, including lower risk of certain cancers, increased weight loss, improved heart health, and protection against Alzheimer's.
Green tea contains between 30 and 40 per cent of water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3 and 10 per cent.
The four primary polyphenols found in fresh tealeaves are epigallocatechin gallate (EGCG), epigallocatechin, epicatechin gallate, and epicatechin.
The new study, published in the journal Cancer Epidemiology Biomarkers & Prevention, looked at the link between green tea consumption and the risk of colorectal cancer (CRC) among 69,710 Chinese women aged between 40 and 70.
There are 363,000 new cases of colorectal cancer every year in Europe, with an estimated 945,000 globally. About 492,000 deaths occur from the cancer each year.
Lead author Gong Yang from Vanderbilt University School of Medicine and co-workers from Shanghai Cancer Institute, and National Cancer Institute, National Institutes of Health, followed the subjects for six years and identified 256 incident cases of CRC.
Regularly drinking tea at baseline was associated with a 37 per cent risk reduction, compared to irregular tea consumption.
The researchers found the reduction in risk to be related to the dose of tea regularly consumed, and the duration of lifetime tea consumption.
"The reduction in risk was most evident among those who consistently reported to drink tea regularly at both the baseline and follow-up surveys (risk reduction of 57 per cent)," wrote Yang and co-workers.
"This study suggests that regular consumption of green tea may reduce CRC risk in women," they concluded.
European demand for tea extracts is currently surging, and this has seen companies such as DSM, with its Teavigo boasting 95 per cent purity of EGCG, and Taiyo International, with its Sunphenon claiming more than 90 per cent purity, position themselves firmly in specific catechin markets.
Source: Cancer Epidemiology Biomarkers & Prevention
Volume 16, Pages 1219-1223, doi: 10.1158/1055-9965.EPI-07-0097
"Prospective Cohort Study of Green Tea Consumption and Colorectal Cancer Risk in Women"
Authors: G. Yang, X.-O. Shu, H. Li, W.-H. Chow, B.-T. Ji, X. Zhang, Y.-T. Gao and W. Zheng