Dark chocolate may help guard against brain injury after a stroke, U. S. researchers have concluded.

Modest amounts of a compound in dark chocolate, epicatechin, helped protect up to 3.5 hours against the brain damage caused when blood supply was cut off to the brains of mice, researchers Johns Hopkins Medical Institutions have found.

Published in the Journal of Cerebral Blood Flow and Metabolism, the study suggested epicatechin helped jump start two previously well-established pathways known to shield brain nerve cells from damage. In mice lacking these pathways, the epicatechin did not prevent brain cells from dying.

His research was not a free pass to eat large amounts of chocolate, which is high in calories and fat, and reminded people to eat a healthy diet with a variety of fruits and vegetables, study leader Sylvian Dore said.

The epicatechin in dark chocolate is extremely sensitive to changes in heat and light, Dore also said.

Dore said in a statement, "In the process of making chocolate, you have to make sure you don't destroy it. Only few chocolates have the active ingredient. The fact that it says 'dark chocolate' is not sufficient." (With Inputs from Agencies)