Cocoa Flavanols May Improve Visual Sensitivity and Cognitive Function


Do you have a test or an important meeting coming up? You might want to indulge in a little dark chocolate a couple of hours before your “performance.” A study from the University of Reading in the UK finds that the consumption of cocoa flavanols may improve aspects of cognitive function as well as improve visual contrast sensitivity.

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A research team led by David T. Field recruited 30 healthy adults between the ages of 18 and 25 years. Each was instructed to consume 35 grams of dark chocolate and a matched quantity of white chocolate, with a one week interval between testing sessions. Both vision and brain functions were tested and compared. The testing lasted approximately 45 minutes.

Visual contrast sensitivity was assessed by reading numbers that became progressively more similar in luminance. Motion sensitivity was assessed by first detecting a signal dot against a background of random motion and next by determining the minimum time required to detect motion in a particular display.
Cognitive performance was assessed using a visual spatial working memory for location task and a choice reaction time task designed to engage processes of sustained attention and inhibition.

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Cocoa flavanols (CF) almost immediately improved visual function. The team noted benefits in just 2.5 hours after eating the chocolate. The team noted improved visual contrast sensitivity and the time required to detect motion direction was reduced. Eating the darker chocolate also improved spatial memory and performance on some of the aspects of the choice reaction time task.

The researchers propose that increased blood flow to the retina and brain explained the improvements in function. Theobromine, a naturally occurring compound in cocoa, has previously been found to improve blood vessel function. The caffeine content may also act as an antioxidant.

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“A reduction in the time required to integrate visual motion could be beneficial in time critical everyday tasks, such as driving. The effect on the simpler early phase of the choice reaction time task suggests that CF can increase response speed in simple tasks,” conclude the authors.

Journal Reference:
David T. Field, Claire M. Williams, Laurie T. Butler. “Consumption of cocoa flavanols results in an acute improvement in visual and cognitive functions.” Physiology & Behavior, Volume 103, Issues 3-4, Pages 255-260, 1 June 2011.