There's nothing like a cup of hot cocoa on a blustery day. According to one study, some kinds of cocoa could not only taste good, but be good for you, too.

Cocoa contains chemical compounds called flavanols. Scientists think that flavanols boost the level of nitric oxide in the blood, which in turn makes arteries more flexible. The more flexible an artery, the better able it is to expand as it fills with blood and contract as it pushes blood farther down the line.

Some compelling evidence for the arterial benefits of flavanols comes from the San Blas islands near Panama. The Kuna Indians who live there drink a kind of cocoa high in flavanols. Kuna who live on mainland Panama, though, don't drink the cocoa. Researchers found that the island-dwelling Kuna have much lower rates of cardiovascular disease and cancer than the mainland dwellers.

This doesn't mean that flavanols are the only reason why island-dwelling Kuna tend to be healthier, but researchers think it's an important part of the mix. Add in several other studies showing the benefits of flavanols for blood flow, and they begin to seem pretty attractive. One study showed that flavanols can reverse arterial damage caused by smoking. Another found that when study participants over 50 drank flavanol-rich cocoa for several weeks, blood flow to their brains increased significantly.

Don't go out and stock up on hot chocolate mix just yet. Flavanol has a bitter taste, so most cocoa in stores is low in flavanols. However, if the health benefits of flavanols continue to pan out, you can bet that flavanol-rich cocoa mix will soon be appearing on supermarket shelves.