This is not the first study to tout chocolate's potential benefits: in 2008, Italian researchers found that eating dark chocolate regularly may help lower levels of inflammation, which is strongly associated with heart and blood vessel disease. The previous year, another study showed that foods rich in antioxidants known as flavonoids - including dark chocolate and apples and red wine -- may help shield postmenopausal women from coronary heart disease, cardiovascular disease and stroke. Flavonoids are thought to reduce the risk of heart disease, the leading cause of death in many industrialized countries, by helping to increase nitric oxide, which in turn helps boost the functioning of blood vessels and lower blood pressure.
To investigate further, the authors reviewed data collected from 1216 older women, who estimated how often they ate chocolate, and the amount. One serving consisted of the equivalent amount of cocoa in 1 cup of hot cocoa. The authors tracked the women for almost a decade, noting who was hospitalized or died from heart disease. Roughly half of the women said they ate less than one serving of chocolate per week. Nearly 90 of those who ate chocolate rarely were hospitalized or died from heart disease during the study period, versus 65 women who ate chocolate more frequently. Another 35 of the infrequent consumers experienced heart failure, while only 18 women who reported eating chocolate at least once per week were hospitalized or died from the same condition, the authors report in the Archives of Internal Medicine. Although they grouped women who ate chocolate daily and weekly together, the authors also looked at each separately, and found that both appeared to fare equally well, suggesting that only one serving per week might suffice to get heart benefits.
The study's nature means researchers can't prove any cause-effect relationship. Given the growing body of evidence suggesting the benefits of chocolate, the next step should be a large clinical trial that vigorously tests chocolate's benefits, Lewis said in an e-mail. Buijsse agreed that more research is needed, in part because other factors in the current study may explain its results. For instance, he said in an e-mail, elderly women with early signs of heart disease may have reduced their chocolate intake, perhaps because their doctors told them to adopt a healthy diet. "For now, I would say that if people want to eat chocolate to improve their health, they should keep it to low amounts and replace it for other energy-dense snacks," Buijsse said.