As Joyce Hendley reported in EatingWell Magazine, a large study out of Harvard, published in 2010, found that women who ate one or two ounces of chocolate a week had a 32 percent lower risk of heart failure than women who ate no chocolate. It’s possible that compounds in cocoa called flavanols help activate enzymes that release nitric oxide—a substance that helps widen and relax blood vessels. That allows blood to flow through the vessels more freely, reducing blood pressure. Nitric oxide is also involved in thinning blood and reducing its tendency to clot—lowering, potentially, the risk of stroke. Not only that, some of the key flavanols in cocoa, catechins and epicatechins (also found in red wine and green tea), are known to have heart-healthy, antioxidant effects—such as helping to prevent artery-threatening LDL cholesterol from converting to a more lethal, oxidized form.