Black and green tea consumption and the risk of coronary artery disease: a meta-analysis

Background: Epidemiologic studies are inconsistent regarding the association between tea consumption and the risk of coronary artery disease (CAD). Objective: The objective was to perform a meta-analysis to determine whether an association exists between tea consumption and total CAD endpoints in observational studies. Design: We searched PUBMED and EMBASE databases for studies conducted from 1966 through November 2009. Study-specific risk estimates were combined by using a random-effects model. Results: A total of 18 studies were included in the meta-analysis: 13 studies on black tea and 5 studies on green tea. For black tea, no significant association was found through the meta-analysis [ highest compared with lowest, summary relative risk (RR): 0.92; 95% CI: 0.82, 1.04; an increment of 1 cup/d, summary RR: 0.98; 95% CI: 0.94, 1.02]. For green tea, the summary RR indicated a significant association between the highest green tea consumption and reduced risk of CAD (summary RR: 0.72; 95% CI: 0.58, 0.89). Furthermore, an increase in green tea consumption of 1 cup/d was associated with a 10% decrease in the risk of developing CAD (summary RR: 0.90; 95% CI: 0.82, 0.99). Conclusions: Our data do not support a protective role of black tea against CAD. The limited data available on green tea support a tentative association of green tea consumption with a reduced risk of CAD. However, additional studies are needed to make a convincing case for this association. Am J Clin Nutr 2011;93:506-15.