Blueberries are super stars among health food advocates, who tout the fruit for not only promoting heart health, better memory and digestion, but also for improving night vision. Scientists have taken a closer look at this latter claim and have found reason to doubt that the popular berry helps most healthy people see better in the dark. Their report appears in ACS' Journal of Agricultural & Food Chemistry.
Wilhelmina Kalt and colleagues note that studies published decades ago provided the first hints that blueberries might improve people's night vision. Later lab experiments appeared to shore up these early findings. For example, anthocyanins, which are pigment molecules in blueberries and other plants, encourage the regeneration of key molecules in the eye involved in perceiving light. But reviews of the earlier clinical research that tested the effect of blueberries on night vision in human subjects revealed that the studies were poorly controlled. Kalt's team wanted to revisit the matter with a new set of carefully designed experiments.
The researchers found that a blueberry-supplemented diet did not improve sight in the dark, but they did help subjects recover normal vision after exposure to a bright light. The enhancement, however, was small and not likely noticeable to most healthy people, the researchers concluded. But they added that anthocyanins might improve visual health among people who have existing eye disorders, though this remains to be demonstrated with well-designed studies.
The authors acknowledge funding from Agriculture & Agri-Food Canada and the U.S. Highbush Blueberry Council.
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