The 30 subjects who participated in the study consumed three different drinks on different days – one a cocoa drink with 520 milligrams of flavanols, another cocoa concoction with 993 milligrams of flavanols and a third drink with no flavanols. Each subject was asked to perform a mentally demanding task, such as counting backward by threes from 999.
It was found that when the participants took the flavanol drinks, they performed considerably better on the mental tasks than when they consumed the dummy drink. Moreover, the flavanols appeared to counteract the weariness from the strenuous mental exertion.
“We asked them about their mental fatigue, and that increased, but the cocoa offset that increase,” said researcher Crystal Haskell.
“Foods containing high levels of cocoa flavanols … have been shown to increase cerebral blood flow,” she said, “and it has also been proven that consumption of plants that have these properties improves performance on mentally demanding tasks. We wanted to discover whether cocoa flavanols produced the same effect.”
The researchers found that the 520-milligram flavanol drink worked best. But this is the amount contained in fully five bars of chocolate – a very high dose. The scientists are now trying to find whether lower doses are also effective.
“The amounts we were giving them were more than you would get from eating small amounts in diet,” said co-researcher David Kennedy. “But there is quite a bit of evidence showing that general consumption over time is protective against neurodegenerative disease and decline in cognitive function.”