Short-term improvements in vision may be possible through the consumption of dark chocolate, compared with milk chocolate, according to a study published in JAMA Ophthalmology.

Jeff C. Rabin, OD, MS, PhD, of the University of Incarnate Word Rosenberg School of Optometry in San Antonio, and colleagues conducted a small, randomized clinical trial with 30 participants to assess the short-term effects of consuming certain chocolates on visual acuity and large- and small-letter contrast sensitivity (primary outcomes).

Individuals without pathologic eye diseases were eligible to participate. Each volunteer consumed dark and milk chocolate at different points in the analysis. Visual acuity and large- and small-letter contrast sensitivities were recorded 1.75 hours post-consumption.

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Of the 30 participants, 21 were women (9 men) and the average reported age was 26 years. For small-letter contrast sensitivity, dark chocolate consumption was significantly better than milk chocolate (average improvement, 0.15) and large-letter contrast sensitivity was insignificantly higher after dark chocolate intake (average improvement, 0.05). Slight enhancements in visual acuity were also observed after dark chocolate consumption, compared with milk chocolate (average improvement, 0.04). Statistical combination of all visual fields analyzed resulted in an overall significant improvement after dark chocolate intake (average improvement, 0.20).

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“Contrast sensitivity and visual acuity were significantly higher 2 hours after consumption of a dark chocolate bar compared with a milk chocolate bar, but the duration of these effects and their influence in real-world performance await further testing,” reported the authors.


Rabin JC, Karunathilake N, Patrizi K. Effects of milk vs dark chocolate consumption on visual acuity and contrast sensitivity within 2 hours: a randomized clinical trial. [published online April 26, 2018]. JAMA Ophthalmol. doi:10.1001/jamaophthalmol.2018.0978