Drinking two or more cups of coffee a day may actually lower a woman's chances of having a stroke, according to a study of more than 80,000 female health professionals published in the March 3 issue of Circulation. The benefit appears to be specific to coffee: other caffeinated drinks such as tea and soft drinks did not reduce the risk of stroke.
These results are surprising because some previous studies have linked coffee drinking with high blood pressure and high cholesterol, both of which raise a woman's stroke risk. However, recent research has also found that coffee does not increase your risk of developing heart disease, and may even protect against type 2 diabetes (an important heart disease risk factor). This is the first study to look specifically at the connection between coffee and stroke in women. Studies in men have had conflicting results, with some finding higher risk and others lower risk the more coffee you drink.
This study looked at the coffee habits of 83,076 women in the Nurse's Health Study. Every few years between 1980 and 2004, the women were asked about their consumption of coffee and other drinks and monitored for health outcomes. Researchers found that women who drank two or more cups of coffee each day had a 20% lower risk of stroke than coffee abstainers. This was true even after other health conditions like high blood pressure, high cholesterol, and diabetes were taken into account.
Even decaf coffee appeared to have benefits: women who drank two or more cups a day experienced an 11% decrease in stroke risk, although the total number of women who drank decaf was too small to be sure this result was not due to chance. Another important finding was that women who smoked appeared to miss out on the stroke benefits of coffee.
While the results of this study are interesting, the researchers stopped short of recommending that women drink coffee to prevent a stroke. They noted that the reduction in stroke risk was small, and that the biological basis for coffee's apparent benefits is not yet known. Further studies will be needed to investigate what ingredients in coffee are protective against stroke, and to see whether the benefits apply to women who are already at increased risk.
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Source: Lopez-Garcia E, Rodriguez-Artalejo F, et al. Coffee Consumption and Risk of Stroke in Women. Circulation. 2009;119:1116-1123