Tuesday, April 18th, 2017

The January 2017 issue of the Journal of Epidemiology published an analysis of two ongoing prospective studies conducted in China which found an association between regular consumption of green tea and a lower risk of cardiovascular and all-cause mortality during a median follow-up period of 8.3 years for men and 14.2 years for women.

The current analysis included 51,920 men enrolled in the Shanghai Men's Health Study, established in 2002 to 2006, and 64,034 participants in the Shanghai Women's Health Study, established from 1997 to 2000. Subjects were between the ages of 40 and 70 years upon enrollment. Interviews conducted at the beginning of the study provided information concerning whether the subjects consumed tea regularly, at what age they started consuming the beverage, and type and amount of tea consumed each month.

During the follow-up periods examined, 2,741 deaths were documented among the men and 3,776 fatalities occurred among the women. Compared to subjects who were not green tea drinkers, there was a 5% lower adjusted risk of mortality from any cause over follow-up in association with drinking green tea regularly, and an 11% lower risk among green tea drinkers who never smoked. When deaths from cardiovascular disease were examined, the reduction in risk was 14% lower for regular consumers of green tea.

The results were most impressive in men who were nonsmokers. Among nonsmokers, men who were green tea drinkers experienced a 19% lower adjusted risk of dying over follow-up. This group also experienced an increased benefit from drinking a greater quantity of green tea, which was associated with a 20% lower risk of mortality from any cause compared to men who were not green tea consumers.

The authors, from Shanghai Jiaotong University School of Medicine in China and Vanderbilt University School of Medicine in the U.S., remarked that green tea's health-promoting effects have been attributed primarily to its polyphenols, which mainly consist of catechins. Catechin intake may favorably impact endothelial and overall vascular function by inhibiting oxidation and inflammation, and improving blood lipids. Experimental research findings indicate that green tea could have an antitumorigenic effect, and may help lower blood pressure and glucose.

"Consequently, green tea consumption could be related to longevity, given its protective effects in reducing risk factors of various chronic medical conditions, especially cardiovascular disease," Long-Gang Zhao and colleagues conclude.