SAN FRANCISCO - A nice cup of the right kind of cocoa could hold the promise of promoting brain function as people age.

In an increasingly aging world, medical researchers are seeing more cases of dementia and are looking for ways to make brains work better.

One potential source of help may be flavanols, an antioxidant found in cocoa beans that can increase blood flow to the brain, researchers said Sunday at the annual meeting of the American Association for the Advancement of Science.

Ian MacDonald of England's University of Nottingham reported on tests given to young women who were asked to do a complex task while their brains were being studied with magnetic resonance imaging.

Among the women given drinks of cocoa high in flavanols, there was a significant increase in blood flow to the brain compared with subjects who did not drink the cocoa, he said.

This raises the prospect of using flavanols in the treatment of dementia, marked by decreased blood flow in the brain, and in maintaining overall cardiovascular health, he said.

The next step, MacDonald said, is to move from healthy subjects to people who have "compromised" blood flow to the brain.

Norman Hollenberg of Harvard Medical School said he found similar health benefits in the Cuna Indian tribe in Panama. They drink cocoa exclusively.

Don't overdo it
But the cocoa typically sold in markets is low in flavanols, which usually are removed because they impart a bitter taste, Hollenberg said. He also said the findings do not mean people should indulge in chocolate.

"Chocolate is a delight. It can never be a health food because we have a calorie problem," Hollenberg said.

But, he added, in cocoa a lot of fat is removed from the chocolate. "I see a bright future for cocoa," he said.

Hollenberg, an expert in blood pressure, studied the Cuna because those who live on native islands do not have high blood pressure.

He said he found that when tribe members move to cities, their blood pressure rises. A major difference is the consumption of their own prepared cocoa, which is high in flavanols. In native areas, that is all they drink; in cities they adopt the local diet.

In addition to having low blood pressure, Hollenberg said, there are no reports of dementia among the native Cuna.

Henriette van Praag of the Salk Institute for Biological Studies discussed the effects of a specific flavanol, Epichatechin, in tests in mice.

She said when that chemical was added to their food, the mice showed improved ability to solve a maze and remembered it longer than mice without the flavanol. She said Epichatechin affected the hippocampus, the brain area important in memory.

In a study reported a year ago, older men in the Netherlands who ate the equivalent of one-third of a chocolate bar every day had lower blood pressure and a reduced risk of death.

The researchers said, however, it was too early to conclude that chocolate led to better health. The men who ate more cocoa products could have shared other qualities that made them healthier.

Hagen Schroeter of Mars Inc., the candy company that paid for some of the research reported Sunday, said that cocoa long has been studied for potential medical benefits. He noted that in addition to cocoa, flavanols occur in other foods such as fruits, tea and wine that have been associated with dilation of the arteries.

Mars last year announced plans to market a line of products under the name CocoaVia which is high in flavanols. Other major chocolate companies, including Hershey's, have started promoting the flavanol content of their dark chocolates.