Two recent Harvard systematic reviews, including a meta-analysis with 2,575 participants published in the Journal of Nutrition, found that cocoa consumption is associated with decreased blood pressure, improved blood vessel health, and improved cholesterol levels, among other benefits.

According to lead researcher, Harvard epidemiologist and nutritionist Eric Ding, Ph.D., consumption of flavonoid-rich cocoa was also linked to reductions in risk factors for diabetes, a major contributor to cardiovascular disease.Resistance to the hormone insulin, which helps regulate blood sugar, favorably dropped among people who consumed cocoa compared to controls.  
 
“Diabetics are insulin resistant, which means their body’s cells grow deaf and unresponsive to this vitally important hormone. Our research found that high-flavanol cocoa both lowers insulin and insulin resistance – thereby improving sensitivity. The body gets better at pulling dangerous sugar out of the blood stream quicker, which is good for fighting against diabetes,” Dr. Ding explained. His research and another Harvard study published in the spring of 2012 together showed that cocoa counters the effects of obesity connected to insulin resistance.
 
“High flavanol cocoa improves blood flow via endothelial function (as measured by improved flow-mediated dilation)—which benefits the entire body. Good circulation is the key to heart and brain health, and diabetes risk is increased by poor endothelial blood flow. Diabetes prevention is also key to preventing kidney problems, blindness, and related nerve damage—all major side effects of diabetes,” he said. “Interestingly, erectile dysfunction is also fundamentally a circulation problem—Viagra® is also shown to improve flow-mediated dilation, similar to cocoa.”