The secret to dark chocolate’s health benefits may be in our guts. New research has found that bacteria in our stomachs feast on an indigestible part of cocoa, fermenting it into anti-inflammatory compounds that are good for the heart, the Los Angeles Times reports. The key lies in anti-oxidants called polyphenols, which are found in dark chocolate and cocoa powder as well as dark berries and black tea. The molecules in many polyphenols are too large to be absorbed through the stomach wall into the blood to be used as nutrients—which is where intestinal microbes lend a hand. In an experimental setting in the lab, researchers found that Bifidobacterium and lactic acid bacteria broke the polyphenols down into smaller molecules capable of making it into the blood. “When these compounds are absorbed by the body, they lessen the inflammation of cardiovascular tissue, reducing the long-term risk of stroke,” Louisiana State University food science professor John Finley says. The amount of cocoa powder needed to produce benefits is about two tablespoons per day.