LOS ANGELES, CALIFORNIA. Several studies have shown that habitual consumption of green tea is protective against cardiovascular disease, breast cancer, and prostate cancer. Now researchers at the UCLA School of Medicine report that habitual tea (green or black) drinking is also associated with a reduced risk of stroke.
The researchers performed a meta-analysis of 10 studies from 6 different countries (China, Japan, Finland, the Netherlands, Australia and the USA). Mortality from stroke (ischemic and hemorrhagic) among 35- to 74-year-old men in these countries ranged from 3 per 10,000 in Australia to 24 per 10,000 in rural China. The 10 studies covered 4378 strokes (fatal and non-fatal) that occurred in a total population of 194,965 men and women. The annual incidence of stroke in a subgroup of 162,700 individuals was 0.7% a year. The researchers pooled the results of the 10 studies and arrived at the conclusion that individuals drinking 3 or more cups of green or black tea every day had a 21% lower risk of stroke than did those consuming less than one cup a day. They speculate that the protective effect of tea may be due to its ability to improve endothelial function and thereby increase blood flow to the brain, or to the ability of one of its components (theanine) to reduce the size of the area impacted by a stroke. They also point out that the protective effect of tea is primarily evident in the case of ischemic stroke and is likely to be considerably less important, if important at all, in the prevention of hemorrhagic stroke.
Arab, L, et al. Green and black tea consumption and risk of stroke: a meta-analysis. Stroke, Vol. 40, May 2009, pp. 1786-92
Editor's comment: Although there is, as yet, no conclusive evidence that green tea extract in capsule from provides the same benefits as green tea itself, it may be advisable for those who do not drink tea to supplement with a green tea extract containing its two most important components epigallocatechin and gallate (EGCG) and theanine.