Swedish Study Suggests Drinking Coffee Associated with Lower Stroke Risk

A new study analyzing data collected from 34,670 Swedish women, aged 49 to 83, found that those who reported drinking from 1 to 5 cups of coffee daily had a 22 to 25 percent lower risk of stroke than those who drank less than 1 cup per day.  “Even small amounts of coffee may reduce the risk of stroke,” said Dr. Susanna Larsson, the study’s lead researcher.  And those who don’t drink coffee at all actually may be increasing their risk for stroke, the researchers reported.

The study was conducted by a team led by Susanna Larsson, PhD, from the Division of Nutritional Epidemiology, National Institute of Environmental Medicine, Karolinska Institutet in Stockholm, Sweden, and including other researchers from the Department of Chronic Disease Prevention, National Institute for Health and Welfare, Helsinki, Finland. It is published in the March 1, 2011 issue of Stroke.

The team collected data on 34,670 women, aged 49 to 83, without a history of cardiovascular disease or cancer at the beginning of the study in 1997, who took part in the Swedish Mammography Cohort, the purpose of which was to measure associations between diet, lifestyle and disease. Researchers followed the study population for an average of 10.4 years. During this period, from 1998 to 2008, 1,680 women among the study population had a stroke. The researchers found, however, that the coffee drinkers had a 22 percent to 25 percent lowered risk of stroke.

The risk levels were similar for those who reported drinking 1-2 cups per day, 3-4 cups per day, or 5 or more cups per day.  All had between 22 percent and 25 percent lower risk of stroke than those who drank less than one cup of coffee per day.

The results remained unchanged even after taking into account smoking status, body mass index (weight), history of diabetes or hypertension, and alcohol consumption

As to why coffee may lower stroke risk, the study’s authors postulated that perhaps coffee reduces inflammation.  Or, it may lower oxidative stress and improve insulin resistance.  These biological effects may explain why drinking coffee appears to correlate with lowered risk of stroke.  However, the researchers cautioned, that their findings are preliminary, and further research is needed before the apparent correlation between coffee drinking and stroke can be deemed established and the reasons for such apparent correlation can be understood.

At least one other expert has been quoted as raising doubts about the study, claiming that other uncontrolled and unmeasured factors, such as medication use or whether the subjects changed their coffee consumption behavior over time, may have affected the study’s findings and accounted for some or all of the correlation found. This expert also questioned whether findings based on the homogeneous Scandinavian population can be extrapolated to other more diverse populations in other parts of the world.

Yet, other studies conducted on other populations have also found a link between regular coffee drinking and reduced risk of stroke. In one such study reported at the American Stroke Association’s annual stroke conference in 2010, British researchers at the University of Cambridge studied 23,000 men and women who were followed for an average of 12 years, and found that those who reported any intake of coffee had a 27 percent lower risk of stroke than those who said they never drank coffee.

Similarly, in another study published online in Arteriosclerosis, Thrombosis and Vascular Biology on June 18, 2010, researchers at the University Medical Center Utrecht studied 37,514 residents of The Netherlands for 13 years. They found that those who drank two to four cups of coffee per day had a 20 percent lower risk of heart disease than those who drank less than two or more than four cups per day.

See the website of the American Heart Association for its current view on the extent of links between caffeine and coronary heart disease.

For more information on stroke, see MedlinePlus Stroke Page, the health information site of the U.S. National Library of Medicine, National Institutes of Health, under the U.S. Department of Health & Human Services.

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