A May 2017 study concluded that, “Consuming moderate amounts of chocolate was associated with significantly lower risk of being diagnosed with atrial fibrillation (AF)--a common and dangerous type of irregular heartbeat.”
“The benefit levelled off slightly with greater amounts of chocolate consumption, with those eating one or more servings per day having a 16% lower AF rate … Eating excessive amounts of chocolate is not recommended because many chocolate products are high in calories from sugar and fat and could lead to weight gain and other metabolic problems. But moderate intake of chocolate with high cocoa content may be a healthy choice."