Dark Chocolate Can Improve Contrast Sensitivity, Visual Acuity

Composite score combining results from all tests showed improvement after dark vs. milk chocolate
Composite score combining results from all tests showed improvement after dark vs. milk chocolate

HealthDay News — Compared with milk chocolate, consumption of dark chocolate is associated with higher contrast sensitivity and visual acuity within 2 hours, according to a study published online April 26 in JAMA Ophthalmology.

Jeff C. Rabin, OD, PhD, from the University of the Incarnate Word Rosenberg School of Optometry in San Antonio, and colleagues compared the short-term effects of dark and milk chocolate consumption on visual acuity in a randomized study. Thirty participants without pathologic eye disease consumed dark and milk chocolate in separate sessions; outcomes were assessed in within-participant paired comparisons. 

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The researchers found that small-letter contrast sensitivity was significantly higher after consumption of dark versus milk chocolate (mean improvement, 0.15 logCS; 95% confidence interval, 0.08 to 0.22 logCS; P<.001). Slightly higher large-letter contrast sensitivity was seen after dark versus milk chocolate consumption (mean improvement, 0.05 logCS; 95% confidence interval, 0 to 0.1 logCS; P=.07). Visual acuity improved slightly more after consumption of dark vs milk chocolate (mean improvement, 0.04 logMAR; 95% confidence interval, 0.02 to 0.06 logMAR; P=.05). In composite scores combining results from all tests, there was significant improvement after consumption of dark versus milk chocolate (mean improvement, 0.2 log U; 95% confidence interval, 0.1 to 0.3 log U; P<.001).

"The duration of these effects and their influence in real-world performance await further testing," the authors write.

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