SMH, September 14, 2006

Those who drink a lot of green tea live longer, a study of more than 40,000 men and women in Japan has found.
The investigation in Sendai, Japan, found the beverage was particularly effective in fighting heart disease but did not reduce the death rate due to cancer, as some earlier animal studies had suggested.
Polyphenols - plant compounds known to be antioxidants - found in green tea may explain the life prolonging benefit it confers, said the study published in the Journal of the American Medical Association.
The 11-year study was conducted in northeastern Japan, a region where 80 percent of the population drinks green tea and more than half drink three or more cups daily.
Those involved in the study ranged in age from 40 to 79 and had no history of stroke, heart disease or cancer when the study began in 1994.
Those who drank five or more cups of green tea a day had a death rate overall and from heart disease in particular that was 16 percent lower than those who drank less than one cup daily, over the course of 11 years.
Over the first seven years of the study the death rate of the heavy tea drinkers was 26 percent lower.
Where heart disease was concerned the effect was stronger among women than men in the study, perhaps because men were more likely to be cigarette smokers, the authors reported.
Tea of all kinds is the most consumed beverage in the world aside from water, while heart disease and cancer are the two leading causes of death worldwide.
The study said the apparent protective effect found was not likely to be the result of tea drinkers somehow being more health conscious, since almost all Japanese consume green tea as one of their favorite beverages regardless of their other health habits.


REUTERS

Green Tea Consumption and Mortality
In vitro and animal data suggest that green tea consumption may protect against cardiovascular disease (CVD) and cancer, but data from human studies are lacking. Kuriyama and colleagues report results of a prospective cohort study of Japanese adults who had no history of CVD or cancer at baseline. During 11 years of follow-up, the authors found significant inverse associations of green tea consumption with reduced all-cause and CVD mortality, particularly among women, but found no association with cancer mortality.

Green Tea Consumption and Mortality Due to Cardiovascular Disease, Cancer, and All Causes in Japan
The Ohsaki Study

Shinichi Kuriyama, MD, PhD; Taichi Shimazu, MD; Kaori Ohmori, MD, PhD; Nobutaka Kikuchi, MD; Naoki Nakaya, PhD; Yoshikazu Nishino, MD, PhD; Yoshitaka Tsubono, MD, PhD; Ichiro Tsuji, MD, PhD
JAMA. 2006;296:1255-1265.

Context  Green tea polyphenols have been extensively studied as cardiovascular disease and cancer chemopreventive agents in vitro and in animal studies. However, the effects of green tea consumption in humans remain unclear.

Objective  To investigate the associations between green tea consumption and all-cause and cause-specific mortality.

Design, Setting, and Participants  The Ohsaki National Health Insurance Cohort Study, a population-based, prospective cohort study initiated in 1994 among 40 530 Japanese adults aged 40 to 79 years without history of stroke, coronary heart disease, or cancer at baseline. Participants were followed up for up to 11 years (1995-2005) for all-cause mortality and for up to 7 years (1995-2001) for cause-specific mortality.

Main Outcome Measures  Mortality due to cardiovascular disease, cancer, and all causes.

Results  Over 11 years of follow-up (follow-up rate, 86.1%), 4209 participants died, and over 7 years of follow-up (follow-up rate, 89.6%), 892 participants died of cardiovascular disease and 1134 participants died of cancer. Green tea consumption was inversely associated with mortality due to all causes and due to cardiovascular disease. The inverse association with all-cause mortality was stronger in women (P = .03 for interaction with sex). In men, the multivariate hazard ratios of mortality due to all causes associated with different green tea consumption frequencies were 1.00 (reference) for less than 1 cup/d, 0.93 (95% confidence interval [CI], 0.83-1.05) for 1 to 2 cups/d, 0.95 (95% CI, 0.85-1.06) for 3 to 4 cups/d, and 0.88 (95% CI, 0.79-0.98) for 5 or more cups/d, respectively (P = .03 for trend). The corresponding data for women were 1.00, 0.98 (95% CI, 0.84-1.15), 0.82 (95% CI, 0.70-0.95), and 0.77 (95% CI, 0.67-0.89), respectively (P<.001 for trend). The inverse association with cardiovascular disease mortality was stronger than that with all-cause mortality. This inverse association was also stronger in women (P = .08 for interaction with sex). In women, the multivariate hazard ratios of cardiovascular disease mortality across increasing green tea consumption categories were 1.00, 0.84 (95% CI, 0.63-1.12), 0.69 (95% CI, 0.52-0.93), and 0.69 (95% CI, 0.53-0.90), respectively (P = .004 for trend). Among the types of cardiovascular disease mortality, the strongest inverse association was observed for stroke mortality. In contrast, the hazard ratios of cancer mortality were not significantly different from 1.00 in all green tea categories compared with the lowest-consumption category.

Conclusion  Green tea consumption is associated with reduced mortality due to all causes and due to cardiovascular disease but not with reduced mortality due to cancer.

Author Affiliations: Division of Epidemiology, Department of Public Health and Forensic Medicine, Tohoku University Graduate School of Medicine (Drs Kuriyama, Shimazu, Ohmori, Kikuchi, Nakaya, and Tsuji), and Division of Health Policy, Tohoku University School of Public Policy (Dr Tsubono), Sendai, Japan; Division of Epidemiology, Miyagi Cancer Center Research Institute, Natori, Japan (Dr Nishino).