In our review of cocoa health science published to date, we found that the most compelling (and best-studied) effect has to do with cocoas effects on blood pressure.
Theres promising evidence showing cocoa flavanols can increase the synthesis of nitric oxide in the blood vessels, which boosts blood flow (or vasodilation) and reduces blood pressure. Lower blood pressure has been linked with a lower risk of cardiovascular events like heart attack, stroke, and cardiovascular mortality. According to a Cochrane systematic review of the cocoa research on blood pressure, flavanol-rich chocolate and cocoa products cause a small (2 mmHg) blood pressure-lowering effect in mainly healthy adults in the short term.
Chocolates heart health benefits are extremely appealing at a time when heart disease is still the leading cause of death in America. When researchers have run big, high-quality observational studies, following many peoples diets, theyve found associations between chocolate eating and a lower risk of cardiovascular problems and many of these studies werent funded by the industry.
Heres the hitch, though: Cocoas effects on blood flow have never been directly linked to a lowered risk of cardiovascular events. So cocoa may impact blood pressure in the short term, but its never been proven to reduce the risk of heart disease or heart attacks. And observational studies can only show correlations between phenomena not that eating chocolate caused the reductions in heart problems. It may be that chocolate eaters are wealthier or have other characteristics, aside from their chocolate-eating habit, that protect them from disease.
Whats more, while fresh cacao beans are rich in flavanols, the nutrient can get destroyed during chocolate processing, so most candy bars dontdeliver the potentially blood-boosting stuff. (Mars now markets its CocoaVia products as being made with gently handled cocoa beans that preserve and protect the cocoa flavanols inside.)
Researchers are now trying to sort out whether the promising smaller trials and observational studies on cocoa and heart health translate into fewer clinical events like heart attacks through a major randomized controlled trial called COSMOS, run by researchers at Brigham and Womens Hospital, an affiliate of Harvard Medical School, and the Fred Hutchinson Cancer Research Center in Seattle.
Interestingly, that study focuses on the effects of cocoa supplements, not chocolate, since supplements are a better flavanol delivery vehicle. COSMOS and its ancillary studies also happen to be funded by Mars Symbioscience, as well as Pfizer Inc. and the National Institutes of Health the culmination of its decades-long investment in searching for chocolates health attributes.
