A recent study published in Scientific Reports reveals that consuming dark chocolate can improve retinal vessel function in healthy adults. The prospective, randomized, blind, crossover clinical trial, conducted at the University Vita-Salute, San Raffaele Hospital in Milan, Italy, investigated the effects of dark chocolate on retinal microcirculation.
The study enrolled healthy volunteers between April and July 2021. Participants underwent a comprehensive ophthalmologic evaluation, including spectral-domain optical coherence tomography (SD-OCT), OCT-A, and DVA, before and two hours after consuming either dark chocolate (20g containing 400mg of flavanols) or milk chocolate (7.5g). The primary outcome measures were changes in retinal perfusion, assessed by OCT-A, and changes in retinal vascular response to flicker stimulation, measured by DVA.
The results indicated that dark chocolate intake led to significant improvements in retinal vascular function compared to milk chocolate. Specifically, the study observed positive changes in retinal perfusion and vascular reactivity following dark chocolate consumption. The quantity of chocolate was based on a previous study. To maintain blinding, the examiner and patients were not informed of the type of chocolate administered, although subjects could identify the chocolate by taste.
Methodology
The study included healthy individuals aged 18 years or older, excluding those with ocular pathologies, systemic hypertension, or significant refractive errors (myopia greater than -8.0 diopters, hyperopia greater than 5.0D, or astigmatism greater than 3.0D). Participants were instructed to avoid smoking, caffeine, alcohol, and milk products 24 hours prior to the examinations. All tests were conducted between 9 and 11 a.m. by a single trained grader to minimize variability.
OCT-A was used to measure perfusion density (PD) in the superficial capillary plexus (SCP), deep vascular complex (DVC), and choriocapillaris (CC). DVA assessed the degree of arterial and venous dilation upon stimulation with flicker light. Static vessel analysis was performed using a retinal camera and dedicated software to calculate the central retinal artery equivalent (CRAE) and central retinal vein equivalent (CRVE).
Key Findings
The primary outcomes of the study focused on retinal perfusion changes via OCT-A and vascular response to flicker stimulation via DVA. Statistical analysis, using repeated measures ANOVA with LSD post hoc analysis, revealed significant differences between the effects of dark chocolate and milk chocolate on these parameters. A sample size of 20 eyes was determined to provide sufficient statistical power (greater than 80%) to detect a 5% variation in PD with an alpha error of 0.05.
Clinical Significance
These findings suggest that dark chocolate, rich in flavanols, may have a beneficial impact on ocular health by enhancing retinal microcirculation. Improved retinal vessel function could potentially reduce the risk or slow the progression of various ocular diseases, such as diabetic retinopathy and age-related macular degeneration. However, further research is needed to confirm these benefits and determine the optimal dosage and duration of dark chocolate consumption for improving retinal health.
