Cocoa flavanols rescue stress-induced declines in endothelial function after a high-fat meal, but do not affect cerebral oxygenation during stress in young, healthy adults.

Food choices during stressful periods often worsen, which can influence the impact of stress on vascular health. For instance, fat consumption impairs the recovery of endothelial function following mental stress, while flavanols have been shown to enhance recovery. This randomised, counterbalanced, double-blinded, crossover, postprandial intervention study examined whether flavanols consumed in combination with fat can mitigate the negative impact of fat on stress-induced impairments in endothelial function. Twenty-three young, healthy males and females ingested a high-fat meal (56.5 g fat) with high-flavanol (150 mg (-)-epicatechin) or low-flavanol (<6 mg (-)-epicatechin) cocoa 1.5 hours before an 8-minute mental stress task. The primary outcome, brachial flow-mediated dilatation (FMD), was assessed at pre-intervention baseline and 30 and 90 minutes post-stress. Pre-frontal cortical oxygenation was assessed post-meal at rest and during stress. Forearm blood flow (FBF), blood pressure (BP), cardiovascular activity, common carotid artery (CCA) diameter and blood flow and mood were assessed before, during and/or after stress. FMD was impaired at 30 and 90 minutes post-stress after the low-flavanol cocoa. High-flavanol cocoa attenuated FMD impairments at 30 minutes and improved FMD at 90 minutes post-stress. Mental stress induced similar increases in cortical oxygenation, FBF, BP, cardiovascular activity, and disruptions to mood, in both conditions. CCA diameter increased and CCA retrograde blood flow decreased post-stress, with no difference between conditions. In summary, flavanols can counteract declines in endothelial function induced by consuming fat in the context of stress, but do not impact cerebral oxygenation. These findings can have important implications for flavanol-rich dietary choices to protect the vasculature from stress.