The acute effect of cocoa and red-berries on visual acuity and cone-mediated dark adaptation in healthy eyes

The retina is a highly vascularized tissue with high metabolic and oxygen demand responsible for human vision. Considering that the polyphenolic flavanols anthocyanins have been shown to be beneficial endothelial function cerebral blood-flow, an acute randomized controlled crossover trial two different sources of polyphenols, from red-berries cocoa, was designed better understand effect polyphenols on visual acuity (VA) cone-mediated dark adaptation (DA). Thirty-seven healthy subjects (22.1 ± 2.0 years old) participated in intervention three times (red-berries, cocoa or vehicle-control) washout period weeks in-between. VA under photopic low luminance (mesopic) conditions, DA dynamic recovery contrast threshold (CT) following near-total photopigment bleach 5 min, urine total theobromine antioxidant power were measured study-arms after 2-hours ingestion study-food. 3-hours postprandial showed higher levels comparison vehicle-control only group. There increase did not reach statistical significance. Both, red berries, failed improve mesopic cone time constant final CT DA.