More Evidence Chocolate Lowers Stroke Risk

Allison Gandey

October 27, 2011

October 27, 2011 — Chocolate lovers may have another reason to indulge. A new study shows that consuming chocolate on a regular basis may decrease stroke risk by 20%.

New data on women studied in the Swedish Mammography Cohort found an inverse association between chocolate consumption and total stroke, as well as a trend to reduction in both hemorrhagic stroke and cerebral infarction subtypes.

"Even consuming a relatively small amount of chocolate had quite a large impact on stroke risk," lead investigator Susanna Larsson, PhD, from the National Institute of Environmental Medicine in Stockholm, Sweden, said in a news release. "But women reporting the highest amount of chocolate consumption [66.5 g] — equivalent to about 2 chocolate bars a week — had a significantly reduced risk of stroke, suggesting that higher intakes are necessary for a potentially protective effect."

The results appear in the October 18 issue of the Journal of the American College of Cardiology.

Asked by Medscape Medical News to comment on the findings, Philip Gorelick, MD, from the University of Illinois College of Medicine in Chicago, called the work "provocative."

"Interestingly, women with hypertension had a reduction of stroke risk with chocolate consumption that was not statistically significant, whereas those without hypertension had a statistically significant risk reduction for stroke," he noted. "Higher chocolate consumption seemed to be most beneficial in relation to stroke reduction."

The study included 33,372 women enrolled in the population-based Swedish Mammography Cohort. Using a validated food-frequency questionnaire, the researchers asked participants to disclose how often on average they consumed chocolate and a variety of other foods during the previous year.

Investigators then stratified the women into categories ranging from never eating chocolate to those who indulged 3 or more times a week and examined the risk for stroke during a mean follow-up of 10 years, adjusting for major risk factors associated with stroke.

The researchers identified 1549 strokes. Of these, 1200 were cerebral infarctions, 224 were hemorrhagic strokes, and 125 were unspecified. Chocolate consumption was inversely associated with risk for total stroke, cerebral infarction, and hemorrhagic stroke.

Table. Multivariable Stroke Risk for a 50 g per Week Increase in Chocolate

Stroke Relative Risk 95% Confidence Interval
Total 0.86 0.77 - 0.96
Cerebral infarction 0.88 0.77 - 0.99
Hemorrhagic 0.73 0.54 - 0.99

The difference in risk estimates for cerebral infarction and hemorrhagic stroke was not significant (P = .28).

"The difference between stroke subtypes was not significant, and deserves further study," Dr. Larsson said. "It does appear from the data that the association between chocolate consumption and stroke is expected to be stronger with higher concentration of cocoa in the chocolate."

Chocolate is thought to have cardiovascular benefits resulting from the flavonoids in cocoa that have antioxidant properties. Antioxidants protect the body from damage caused by free radicals and can suppress oxidation of low-density lipoprotein. Dark chocolate consumption has also been shown to reduce blood pressure, which is a strong risk factor for stroke, as well as improve endothelial and platelet function and heighten insulin resistance.

Indulgence in chocolate in moderation remains a reasonable approach.

Still, Dr. Larsson cautions that chocolate, and especially chocolate bars, are high in sugar, fat, and calories and should therefore be consumed in moderation. "Choose dark chocolate," she said, "which is usually lower in sugar and has higher flavonoid content."

On the surface, the results may be good news for women who are chocolate lovers, as they may be protected from stroke, Dr. Gorelick noted.

"One must keep in mind, however, that food-frequency studies focus on individual food components and provide useful information, but may not account for the totality of dietary experience." Overall, scores reflecting many dietary components may be a better indicator of risk for cardiovascular disease and other chronic disease, he suggests.

"For the time being, it is prudent to eat a heart-healthy diet, such as that recommended by the American Heart Association, and not get caught up in overeating chocolates in hopes of warding off strokes," he added. "Diets rich in fruits and vegetables and low in fats such as saturated fats are likely to be the best bet. Indulgence in chocolate in moderation remains a reasonable approach."

This study was supported by the Swedish Council for Working Life and Social Research, the Swedish Research Committee for Infrastructure, and a research fellow grant from the Karolinska Institutet. The investigators and outside commentators have disclosed no relevant financial relationships.

J Am Coll Cardiol. 2011;58:1828-1829. Full text

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