Several recent large-scale research reviews have provided the best evidence yet that chocolate, derived from the seeds of the cocoa tree (Theobroma cacao), is good for your heart.
In one review, published in the British journalBMJin August, 2011,researchers analyzed data from seven observational studies, which included more than 100,000 people. Those who ate the most chocolate had a 37 percent lower risk of heart disease, compared to those eating the least, after controlling for weight, physical activity, education and other dietary factors that could influence the results. They were also 29 percent less likely to have a stroke.
In a second review, in theEuropean Journal of Clinical Nutrition,also in August, 2011, Harvard researchers looked at 10 clinical studies from the last decade, with a total of 320 people. Consuming dark chocolate or cocoa products for twoto 12 weeks modestly lowered cholesterol. And another review of clinical trials, inBMC Medicine,found that cocoa-rich products had a small blood-pressure-lowering effect in people with hypertension and prehypertension.
Behind the benefits
Chocolate’s health benefits are largely attributed to polyphenol compounds called flavonoids—the same family of substances that are in tea, red wine, grape juice and other plant foods—which have antioxidant, anti-inflammatory and anti-clotting properties.
In particular, flavonoids increase production of nitric oxide, which helps relax and dilate blood vessels, and this may help lower blood pressure and have other cardiovascular effects. Cocoa flavonoids may also inhibit cholesterol absorption as well as oxidation of LDL (“bad”) cholesterol, making it less harmful.
But before you reach for a chocolate bar, there are some caveats. First, not all studies have had positive results. And many—including all of those in the recent BMJ analysis—are observational studies. This means the studies don’t prove cause and effect, that chocolate, rather than something else about chocolate eaters, is responsible for the benefits seen.
In addition, no one knows what type or amount of chocolate is optimal. Studies have used different formulations (with widely varying flavonoid levels) and intakes (from tiny daily amounts to impractically large quantities). Some have not distinguished between milk and dark chocolate. Chocolate may affect different people differently, too, depending on a variety of factors.
Keep in mind also that the chocolate confections that Americans love most are loaded with sugar, fat and calories (235 in a typical 1.5-ounce bar). Many have caramel, nougat and other unhealthy fillings and ingredients. Eat too much of any kind of chocolate and you can gain weight, which would likely cancel out the heart benefits.