Foods rich in cocoa may improve performance on challenging mental tasks like arithmetic. This is the finding of a study presented as part of a symposium highlighting the potential of plant-based treatments presented at the British Psychological Society Annual Conference 2009 in Brighton.

Crystal Haskell from the Brain, Performance and Nutrition Research Centre at Northumbria University said: "Foods containing high levels of cocoa flavanols, found in chocolate, have been shown to increase cerebral blood flow, 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.

In the study, 30 healthy adults consumed cocoa drinks on different days containing 520 mg of cocoa flavanols, 993 mg of cocoa flavanols or a control drink. The participants were given a number of mentally demanding tasks to complete, such as counting backwards from 999 in threes.

On the days the participants drank the beverages containing 520mg or 993mg of cocoa flavanols they performed significantly better at the arithmetic task. They also reported being less mentally tired during the task.

Crystal said: "The drink rich in cocoa flavanols significantly improved aspects of cognitive performance and levels of fatigue during this mentally demanding task."

Commenting on the findings David Kennedy says: "Many prescribed drugs were originally derived directly from plants, and we're used to the notion that chemicals from plants, in the form of most social drugs, can affect the functioning of our brains. The results presented in the symposium show that medicinal herbal extracts and plant-derived chemical compounds from common foodstuffs can also improve cognitive performance and mood."