Cocoa has been linked to cardiovascular health benefits since at least the 18th century, but researchers are just beginning to collect scientific evidence for these claims, according to background information in the article. Cocoa is now known to contain chemicals called flavan-3-ols, which have been linked to lower blood pressure and improved function of the cells lining the blood vessels.
Brian Buijsse, M.Sc., National Institute for Public Health and the Environment, Bilthoven, the Netherlands, and colleagues examined cocoa's relationship to cardiovascular health in 470 Dutch men aged 65 to 84 years. The men underwent physical examinations and were interviewed about their dietary intake when they enrolled in the study in 1985 and at follow-up visits in 1990 and 1995. The researchers then placed them into three groups based on their level of cocoa consumption. Information about their subsequent illnesses and deaths were obtained from hospital or government data.
Over the next 15 years, men who consumed cocoa regularly had significantly lower blood pressure than those who did not. Over the course of the study, 314 men died, 152 due to cardiovascular diseases. Men in the group with the highest cocoa consumption were half as likely as the others to die from cardiovascular disease. Their risk remained lower even when considering other factors, such as weight, smoking habits, physical activity levels, calorie intake and alcohol consumption. The men who consumed more cocoa were also less likely to die of any cause.
Although blood pressure is usually linked with risk of cardiovascular death, that was not the case in this study. "The lower cardiovascular mortality risk associated with cocoa intake could not be attributed to the lower blood pressure observed with cocoa use," the authors write. "Our findings, therefore, suggest that the lower cardiovascular mortality risk related with cocoa intake is mediated by mechanisms other than lowering blood pressure." The benefits associated with flavan-3-ols may play a role.
The link between chocolate and overall lower risk of death suggests that other mechanisms also may be involved. "Because cocoa is a rich source of antioxidants, it may also be related to other disease that are linked to oxidative stress (e.g. pulmonary diseases, including chronic obstructive pulmonary disease, and certain types of cancer) ," the authors conclude. "However, this merits further investigation."
(Arch Intern Med. 2006; 166: 411-417. Available pre-embargo to media at www.jamamedia.org.)
Editor's Note: The Zutphen Elderly Study was supported by grants from the Netherlands Prevention Foundation, The Hague.