According to an article by Stephen Daniells on foodnavigator.com, researchers have linked chocolate high in flavanols to increased blood flow in the brain. A recent study was performed on 34 healthy elderly volunteers to find the effects of regular intakes of flavanol-rich cocoa (FRC) and flavanol-poor cocoa (FPC).
The volunteers were split into two groups: The first group of 13 people consumed FRC (900 mg per day, Cocoapro, Mars) regularly for two weeks while the second group of 21 people consumed either daily FRC or FPC for one week in a double-masked, placebo-controlled, parallel-arm study.
The blood flow in all volunteers was measured by using ultrasound methods to measure blood flow in the middle cerebral artery. When the first group was measured, researchers found a 10% increase in blood flow. The other group found an increase in blood flow of at least 10% in 55% of the volunteers who had been consuming FRC for one week. FPC resulted in a blood flow increase in just 10% of the volunteers. Because there was a large variation among the test subjects, researchers have not found the results to be statistically significant.