No evidence of acute effects of cocoa flavanols on overt and covert attention: a randomised, double-blind crossover trial

Abstract Acute consumption of cocoa flavanols (CF) has been reported to enhance cognitive functions, primarily through nitric oxide synthesis within blood vessels. These effects include improved performance in sustained attention, spatial attention and attentional control. However, its effect on covert attention remains unclear. The current study aimed to explore the acute effects of CF on overt and covert attention, using visual attention tasks. In a randomised, double-blind, placebo-controlled crossover study with a counterbalanced design, forty-eight undergraduate students completed the visual search task (VST) and the spatial cueing task across three conditions. A flavanol-rich cocoa beverage (710 mg), a flavanol-free cocoa beverage (placebo) and sugar water (control) were administered in separate testing sessions with a 1-week washout interval. Three-way repeated measures ANOVA revealed that the acute CF intake did not improve accuracy ( F 2,94 = .33, p = .72, η p 2 = .01) or reaction time ( F 2,94 = .67, p = .51, η p 2 = .01) in the VST. Similarly, the main effect of acute CF intake was not significant for accuracy ( F 1·83,85·85 = 1, p = .37, η p 2 = .02) or reaction time ( F 2,94 = .57, p = .57, η p 2 = .01) in the spatial cueing task. Overall, the findings provide no evidence that a single 710 mg dose of CF improves overt or covert attention in healthy young adults. A single acute dose of CF may not be sufficient to improve visual attention performance in the current sample.