Chocolate Linked to Lower Stroke and Stroke Mortality Risk

Results of 2 prospective cohort studies showed, respectively, a 22% reduction in stroke risk for those who had 1 serving of chocolate per week and a 46% reduction in stroke mortality from weekly consumption of flavonoids in 50 g of chocolate vs no consumption. A third study showed no association between chocolate intake and stroke or death.

Chocolate contains cocoa butter, flavonoids, carbohydrates, and vitamins. Previous studies, most of them epidemiological, have shown varying effects of chocolate consumption on the risk for cardiovascular disease, the researchers, with first author Sarah Sahib, BScCA, from McMaster University in Hamilton, Ontario, Canada, write. "Less is known about the risk of stroke in association with flavonoid intake," they note.

To examine this association, the authors carried out a systematic review of studies published between 2001 and 2009, using search terms including flavonoids, flavanols, isoflavones, and anthocyanidins, as well as stroke and mortality.

"We found 88 publications, among them 3 prospective studies, and another retrospective study providing some information on the effect of chocolate consumption on the incident risk of stroke," Dr. Gustavo Saposnik (St Michael's Hospital and the University of Toronto, ON) said. "Two of these studies show a reduction in the incident risk of stroke, and the other two didn't show any substantial difference."

However, although more data on this link would be helpful, Dr. Saposnik pointed to several challenges to doing these kinds of studies. First, it is important to document the actual content of flavonoids or other substances thought to be active in the chocolate being consumed.

"There are some studies that compare the content of flavonoids for different food elements and antioxidant capacity," he said. Dark chocolate is one with the highest flavonoids and procyanidins, which have been associated with lower cardiovascular risk, and in addition, dark chocolate has the highest antioxidant capacity.

Still, there are varying types of chocolate, and the amounts that are required to affect stroke risk may bring a load of sugar and fats that may work counter to the beneficial effects. "50g of chocolate per day is a significant amount," Dr. Saposnik notes.

American Academy of Neurology 62nd Annual Meeting. April 10-17, 2010. Published online February 11, 2009.