The report in the medical journal Hypertension is just the most recent to link dark chocolate with beneficial health effects. In an earlier study, consumption of the bittersweet candy reduced blood pressure and increased insulin sensitivity in healthy subjects.

To determine if this effect also applied to patients with high blood pressure, Dr. Jeffrey B. Blumberg, from Tufts University in Boston, and colleagues randomly assigned 20 subjects to receive dark or white chocolate for 15 days. The researchers assessed blood pressure, insulin sensitivity, and blood vessel function with standard tests.

White chocolate was selected for comparison because, unlike dark chocolate, it does not contain substance called flavonols, which are thought to be responsible for the apparent benefits.

Dark chocolate, but not the white variety, was associated with a significant drop in blood pressure. In addition, dark chocolate reduced LDL ("bad") cholesterol, enhanced insulin sensitivity, and improved blood vessel function.

Still, the authors caution that patients with high blood pressure shouldn't start eating tons of dark chocolate as the confection does contain high amounts of fat, which may ultimately offset the benefits seen.

"The findings do not suggest that people with high blood pressure should eat lots of dark chocolate in lieu of other important blood pressure-reduction methods, such as medication and exercise," Blumberg said in a statement. "Rather, we are identifying specific flavonoids that can have a benefit on blood pressure and insulin sensitivity."

SOURCE: Hypertension, July 18, 2005.