Women in the study who drank more than a cup of coffee a day had a 22% to 25% lower risk of stroke than those who drank less, according to findings reported Thursday in Stroke: Journal of the American Heart Association. Stroke is the third leading cause of death in the USA, behind heart disease and cancer.
Swedish researcher Susanna Larsson of the Karolinska Institute in Stockholm followed 34,670 women ages 49-83 for an average of 10 years. The questionnaire completed by the women did not inquire whether their coffee was regular or decaffeinated, but the authors say the number of people who drink decaf in Sweden is very low.
The findings add to the growing body of research showing coffee appears to have hidden health perks. A study done by Larsson in 2008 on men who drank coffee or tea had similar results.
One of the most popular drinks in the world, coffee contains large amounts of antioxidants that improve health. Other research has suggested coffee can help prevent cognitive decline and can boost vision and heart health. It is also associated with a reduced risk of liver cancer.
"We used to worry that (coffee) raises blood pressure and causes increased heart rate, but it appears to be less risky than we thought," says physician Claudette Brooks, spokeswoman for the American Stroke Association. "We're not sure what it is in coffee that is giving women this stroke protection, though." She says more research is needed before drinking habits change.
In the new study, the women participated in the Swedish Mammography Cohort, a longterm investigation of the association between diet, lifestyle and disease development. None had cardiovascular disease or cancer at a baseline in 1997. Between January 1998 and December 2008, 1,680 strokes were reported.
The results are consistent with findings on 83,076 women in the Nurses Health Study in the USA in 2009. In that study, women who drank four or more cups of coffee a day had a 20% reduced risk of stroke, compared with women who had less than one cup per month. That study distinguished between caffeinated and decaf; the decaf group had a slightly lower risk.
"Coffee consumption was associated with a statistically significant lower risk of total stroke," Larsson says.
In the new study, current smokers saw the least amount of reduction in stroke risk, the authors say, compared with women who never smoked or had given up smoking.