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Eating dark chocolate improved visual acuity...for nearly two hours, an unusual study in JAMA Ophthalmology found. Researchers evaluated 30 patients without pathologic eye disease for visual acuity and large- and small-letter contrast sensitivity 1.75 hours after they consumed either dark or milk chocolate.

Results showed that contrast sensitivity was higher after consumption of dark chocolate compared with milk chocolate...and visual acuity improved slightly after consumption of both dark and milk chocolate. Overall, combined results from the tests showed a significantly higher improvement in patients who ate dark chocolate than those who ate milk chocolate. The researchers attribute the differential to the higher amount of flavanols in dark chocolate...that lead to increased blood flow to the macula. However, the authors caution, “The duration of these effects and their influence in real-world performance await further testing.”