Dark Chocolate Could Improve Vision
Researchers of the University of the Incarnate Word Rosenberg School of Optometry in San Antonio, US, discovered that adults who ate a bar of dark chocolate saw a significant increase in visual clarity and contrast sensitivity in the 2 hours after consumption.
Several studies suggest that dark chocolate from favanol-rich cacao beans may enhance blood flow to central and peripheral nervous systems, improve cardiovascular function, and retard memory loss and other signs and symptoms of degenerative diseases, including Alzheimer and Parkinson diseases. The cacao flavanols in dark chocolate have antioxidant effects that retard and partially reverse degenerative changes in various diseases. Dark chocolate consumption also has been associated with enhanced mood and cognition. Short-term improvement in contrast sensitivity was observed after consumption of dark chocolate and attributed to increased blood flow, although direct evidence is lacking. Moreover, the effect of dark chocolate on other visual functions remains unknown.
The scientists conducted a randomized, masked crossover clinical study to assess effects of dark chocolate vs milk chocolate within 2 hours of consumption on multiple aspects of vision, including contrast and color perception, distraction effects, marksmanship, and visual electrodiagnosis.
A total of 30 adults participated in the study. Two-way, repeated-measures analysis of variance across chocolate type (dark vs milk) and vision test (visual acuity vs large- vs small-letter contrast sensitivity) showed an overall improvement after consumption of dark vs milk chocolate.
The researchers concluded that enhancements in visual acuity and large-letter contrast sensitivity after dark chocolate ingestion were small, and the functional relevance is unclear. However, a more substantial improvement occurred in small-letter contrast sensitivity, a visually challenging task that can reveal decrements and increments in visual performance despite normal high-contrast visual acuity. The highly vascularized retina, particularly the macula with its substantial projection to the visual cortex, may be most susceptible to enhanced blood flow and increased metabolic supply afforded by polyphenol flavanols in dark chocolate. The findings reported suggest that a single dose of dark chocolate improves visibility of small, low-contrast targets within 2 hours compared with milk chocolate, but the duration of this difference and clinical relevance remains uncertain.
The research findings are reported in JAMA Ophthalmology.
