A steaming hot mug of cocoa may be just what the doctor ordered.

Consuming flavonol, an antioxidant found naturally in cocoa, reduces blood pressure and improves circulation, according to a new study co-authored by Harvard Medical School (HMS) Professor of Radiology Norman K. Hollenberg.

Flavonol stimulates the body’s production of nitric oxide, which relaxes blood vessels and leads to a reduction in blood pressure, according to the study released last month.

But Hollenberg said most cocoa products on the market forsake high levels of the healthy antioxidant during processing in order to enhance their sweetness.

“Flavonols are bitter,” he said. “Virtually every cocoa tree in the world makes a high-flavonol cocoa, but human beings have intervened to make [cocoa] taste better and they’ve gotten rid of the flavonols.”

Confectionery giant Mars, a multinational corporation that produces a slew of candies including M&M’s, is already rushing to fill that niche.

Mars recently debuted a new brand of chocolate snacks called Cocoavia, which is advertised to be high in flavonols, according to the Mars website.

Mars sponsored Hollenberg’s research and its Chief Science Officer Harold Schmitz co-authored the study.

HMS Assistant Professor of Medicine Naomi D. Fisher, who has published similar research on flavonol with Hollenberg in the past, said that while flavonol is good for the heart, it is not a preferable alternative to losing weight or quitting smoking.

“None of us think it is a panacea,” Fisher said. “But I can see [flavonol] being part of a heart-healthy diet.”

Hollenberg’s team took two groups of healthy volunteers and gave them cocoa that was either high or low in flavonol, according to the study. Only the group that had taken the high-flavonol drink showed relaxed blood vessels.

The study’s authors then turned to the Kuna Indians in the San Blas islands of Panama, who consume three to four cups of flavonol-rich cocoa a day.

The Kuna Indians on the islands rarely have high blood pressure, according to Hollenberg, which is not true of those Kuna who move to the mainland and, on average, consume less than four cups a week.

—Staff writer Alexander N. Li can be reached at anli@fas.harvard.edu.