Small Study Investigated the Effect of Pure Cocoa Ingestion on Photopic Visual Acuity

Article: 2.5 grammes of pure cocoa found to improve visual acuity in daylight
Source: Universidad Complutense de Madrid (Spain)
Published: May13, 2021
Article: Eating Pure Cocoa May Improve Vision in Daylight
Source: Technology Networks
Published: June 25, 2021

Researchers in Spain explored the effect of two dietary polyphenols—cocoa flavanols and red berry anthocyanins—on visual acuity and cone-mediated dark adaptation in healthy eyes. The study involved 37 healthy volunteers who drank a glass of milk with 2.5 grams of pure cocoa, 10 grams of freeze-dried berry powder, or just milk (control) on three separate visits. Interestingly, this study explored the effect of these polyphenols in acute doses, as compared to longer term dietary routines. Levels of polyphenols in their urine were measured after three hours. Visual acuity was tested in both photopic ("daylight") and mesopic (low light) conditions. Tests of dark adaptation were also performed. Results of the study showed improvement in photopic visual acuity in the group that ingested pure cocoa. This effect was not seen in mesopic conditions with either cocoa or red berry ingestion, and the trend toward improvement in photopic conditions with red berry ingestion was not statistically significant. The investigators hypothesized that the flavanols and theobromine, both alkaloids that stimulate the central nervous system and found in cocoa, increase visual acuity by improving attention or processing of visual information. The authors emphasized that questionnaires and eye examinations were conducted to demonstrate the absence of dietary factors or prior pathology that could influence the analysis of results. However, they also acknowledged that the effect of caffeine, which is also present in pure cocoa, is unknown and could also contribute to the results. Overall, studies into diet potentially have many confounding variables, and a small sample size limits how far results can be extrapolated. The authors conclude, "This work highlights the need for new research that delves deeper into the effect of flavanols, anthocyanins and methylxanthines on visual acuity and attention, both in acute and chronic interventions."

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Puella MC and Pascual-Teresa S. "The acute effect of cocoa and red-berries on visual acuity and cone-mediated dark adaptation in healthy eyes." Journal of Functional Foods.  81:104435. 10 April 2021. https://doi.org/10.1016/j.jff.2021.104435