Men may be able to reduce their risk of having a stroke by about one-sixth, simply by eating one chocolate bar per week.
That's the appetizing conclusion of a large new study from Sweden, the first in a long line of recent studies on the potential heart and vascular benefits of chocolate to look specifically at men.
Researchers at Stockholm's Karolinska Institute followed more than 37,000 men between the ages of 45 and 79 for about 10 years. Compared to those who ate little or no chocolate, men who ate the most—about 2.2 ounces per week—had a 17% lower risk of having a stroke during than timespan.
To bolster these findings, the researchers pooled their data with that from four previous studies, including a near-identical 2011 study they conducted in women. A re-analysis of the combined data produced similar results: Men and women who ate the most chocolate had a 19% lower risk of stroke compared to those who ate the least.
"This was a meaningful reduction in stroke risk, and the results seem to be valid given the high number of patients," says Jonathan Friedman, M.D., a neurosurgeon at the Texas A&M Health Science Center College of Medicine, in Bryan–College Station. Friedman was not involved in the research.
The study, which was funded by a Swedish research council and published today in the journal Neurology, adds to the growing evidence that chocolate, or rather cocoa, has some heart-healthy properties.
Cocoa contains flavonoids, compounds that have been shown to lower blood pressure, increase "good" cholesterol (HDL), and improve the function of arteries. Flavonoids, a type of antioxidant, also may thin the blood and prevent clotting, which could help stave off heart attacks and strokes.
As the authors note, however, other substances in chocolate—or, more likely, certain traits associated with chocolate lovers—could just as easily explain the findings.
The study participants who ate more chocolate tended as a group to be better educated and healthier than their peers. They were less likely to smoke or have high blood pressure, for instance, and they were also less likely to have the heart-rate abnormality known as atrial fibrillation, a major risk factor for stroke.
Although the researchers carefully controlled for these and other health measures (such as diet, body mass index, and physical activity), it's possible that the link between chocolate consumption and strokes can be explained by health or lifestyle differences that went undetected, says Pierre Fayad, M.D., a professor of neurological sciences at the University of Nebraska Medical Center, in Omaha.
"This association could also be due to the fact that [chocolate eaters] are healthier people," Fayad says.
This possibility is made more likely by the fact that the study participants' chocolate consumption and overall health were assessed at a single point in time, at the very beginning of the study.
Nor did the researchers have any information on the type of chocolate the men ate—an important consideration, since cocoa content varies widely by variety, from as little as 30% in milk chocolate to 90% and up in dark chocolate. However, the study does note that 90% of the chocolate consumed in Sweden is milk chocolate.
Even though they jibe with previous research, the new findings aren't likely to dramatically change the advice that doctors give patients about cardiovascular health. Following a healthy diet, exercising regularly, and treating known risk factors such as high blood pressure will all have a bigger impact on stroke risk than chocolate consumption, Fayad says.
And when it comes to chocolate, moderation is key. As Friedman puts it, "Eating five chocolate bars a week might be worse for you in terms of obesity than it is good for you in terms of stroke risk."