Dark chocolate consumption improves the ability to see low- and high-contrast targets, possibly owing to increased blood flow, suggests a small new study from the University of the Incarnate Word Rosenberg School of Optometry in San Antonio, Texas.
Rabin et al found slight improvement in vision after eating dark chocolate. Image credit: © Sci-News.com.
Consumption of dark chocolate can improve blood flow, mood, and cognition in the short term, but little is known about its possible effects on vision.
In a randomized crossover clinical trial, University of the Incarnate Word researcher Jeff Rabin and colleagues compared the short-term effects of consumption of dark chocolate with those of milk chocolate on visual acuity and large- and small-letter contrast sensitivity.
The study involved 30 participants (9 men and 21 women, mean age – 26 years) without pathologic eye disease.
Each participant consumed dark and milk chocolate in separate sessions, and within-participant paired comparisons were used to assess outcomes.
Contrast sensitivity and visual acuity were significantly higher two hours after consumption of a dark chocolate bar compared with a milk chocolate bar.
“Among 30 participants, small-letter contrast sensitivity was significantly higher after consumption of dark chocolate vs milk chocolate,” Dr. Rabin and co-authors explained.
“Large-letter contrast sensitivity was slightly higher after consumption of dark chocolate. Visual acuity improved slightly after consumption of dark and milk chocolate.”
“Composite scores combining results from all tests showed significant improvement after consumption of dark compared with milk chocolate.”
“Randomized clinical trials allow for the strongest inferences to be made about the true effect of an intervention such as a medication or a procedure,” they said.
“However, not all results can be replicated in real-world settings because patient characteristics or other variables may differ from those that were studied in the randomized clinical trial.”
The findings are published in the journal JAMA Ophthalmology.
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Jeff C. Rabin et al. Effects of Milk vs Dark Chocolate Consumption on Visual Acuity and Contrast Sensitivity within 2 Hours: a Randomized Clinical Trial. JAMA Ophthalmology, published online April 26, 2018; doi: 10.1001/jamaophthalmol.2018.0978
