WASHINGTON, March 14 (Xinhua) -- Green tea and coffee may help lower the risk of stroke, especially when both are taken as a regular part of the diet, according to a research published on Thursday in Stroke: Journal of the American Heart Association.
"This is the first large-scale study to examine the combined effects of both green tea and coffee on stroke risks," said Yoshihiro Kokubo, lead author of the study at Japan's National Cerebral and Cardiovascular Center. "You may make a small but positive lifestyle change to help lower the risk of stroke by adding daily green tea to your diet."
Researchers asked 83,269 Japanese adults about their green tea and coffee drinking habits, following them for an average span of 13 years. They found that the more green tea or coffee people drink, the lower their stroke risks.
People who drank at least one cup of coffee daily had about a 20-percent lower risk of stroke compared to those who rarely drank it. People who drank two to three cups of green tea daily had a 14- percent lower risk of stroke and those who had at least four cups had a 20-percent lower risk, compared to those who rarely drank it.
And people who drank at least one cup of coffee or two cups of green tea daily had a 32-percent lower risk of intracerebral hemorrhage, compared to those who rarely drank either beverage.
Intracerebral hemorrhage happens when a blood vessel bursts and bleeds inside the brain. About 13 percent of strokes are hemorrhagic.
Participants in the study were 45 to 74 years old, almost evenly divided in gender, and were free from cancer and cardiovascular disease. During the 13 years of follow-up, researchers reviewed the participants' hospital medical records and death certificates, collecting data about heart disease, strokes and causes of death. They adjusted their findings to account for age, sex and lifestyle factors like smoking, alcohol, weight, diet and exercise.
Tea and coffee are the most popular drinks in the world after water, which suggests that these results may also apply in America and other countries, the researchers said.
It's unclear how green tea affects stroke risks. A compound group known as catechins may provide some protection, according to the researchers.
Catechins have an antioxidant anti-inflammatory effect, increasing plasma antioxidant capacity and anti-thrombogenic effects.