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Will Carrots Help You See Better? No, but Chocolate Might

The views expressed are those of the author and are not necessarily those of Scientific American.


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Bunches of carrotsI can’t count the number of times I have been asked by patients if carrots really can improve their eyesight. I think some are looking for carrots to be a magical cure for their refractive error. They want to eliminate their need for glasses and want carrots to give them perfect 20/20 vision. While proper nutrition is necessary to maintain healthy eyes and can even help slow the progression of certain eye conditions and illnesses such as cataracts and macular degeneration, consuming a certain type of food cannot "cure" your need for glasses. In recent studies, however, it has been shown that what you eat can temporarily enhance the sharpness of your vision and can even improve cognition.

New Studies on Cocoa Flavanols

In May, researchers at the University of Reading in England measured the visual awareness and motion detection skills of 30 healthy young adults two hours after they consumed either dark or white chocolate. Dark chocolate contains antioxidants from cacao beans called cocoa flavanols or CFs, whereas white chocolate contains only trace amounts. The study set out to examine the effects of cocoa flavanols on vision and cognition. Last year a group in Australia and England—including two researchers from Mars UK—had revealed that cocoa flavanols acutely “improve aspects of cognitive function in young healthy adults,” but this new study was the first to focus primarily on the possibility of an enhanced visual performance. (It’s worth noting that the most recent study "was not supported by any cocoa or chocolate companies," according to lead author David T. Field of the University of Reading.)

Stacks of dark chocolareA study about chocolate? Mmmm, where do I sign up?

All kidding aside, the experiment at the University of Reading went like this: 30 people were divided into two groups. One group consumed dark chocolate (containing 720 mg CF), and the other consumed white. Then they were given a series of tests two hours later, when the CFs would be producing their physiological effects. The effects on vision were measured by testing the subjects’ visual contrast sensitivity, motion sensitivity and direction detection time. Cognitive performance was also noted through testing visual spatial memory of locations and choice reaction time tasks. The researchers recorded the results and then, a week later, they actually repeated the same experiment with the same 30 subjects, only this time they swapped sides and switched who consumed what. The 15 white chocolate subjects now consumed dark chocolate instead, and vice versa.

The Influence of Cocoa Flavanols on Vision

What they found, both weeks, was an improvement in visual and cognitive performances of the subjects who consumed the dark chocolate. The subjects who consumed the white chocolate had no real enhancement in their testing performance. This hinted that CFs might temporarily improve certain aspects of vision and cognition in as little as two hours. Researchers think that CFs increase blood flow to the eyes and brain and that this is what leads to enhanced functioning of those structures. The study’s authors wrote that “the results of the current study demonstrate for the first time that performance on tests of visual system function in healthy young adults can be improved by the acute consumption of CF.”

More studies need to be done in this area to find out what this all means and how we could benefit from this knowledge, but oh what fun that research will be! Mmmmmm!

[Editor's note: An earlier version of this article appeared on the author's blog.]

Cheryl G Murphy, ODAbout the author: Cheryl G. Murphy is an optometrist whose passion for vision science and the eye began as an research assistant in undergraduate school at SUNY Albany, where she studied the development of the visual cortex in the brain. She then attended SUNY College of Optometry where she again assisted in vision research, this time on chromatic aberration and its effect on accommodation of the eye. She attained her bachelor of science degree in biology from SUNY Albany in 2000 and her O.D. degree from SUNY Optometry in Manhattan in 2004. Murphy began blogging about eye health and the science of sight in 2008 and now enjoys science writing in her free time. She practices optometry on Long Island, N.Y., where she resides with her husband and four-year-old triplets. Follow her on Twitter at @murphyod

The views expressed are those of the author and are not necessarily those of Scientific American.

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Photo credits: © Forest Woodward/iStockphoto (carrots); © stocksnapper/iStockphoto (chocolate); Erica Angiolillo (author)






Comments 6 Comments

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  1. 1. hungry doggy 2:48 pm 08/3/2011

    Love it! So eating dark chocolates gives you sharper vision and makes you smarter! Next time I munch on a Hersey bar just call me a man of vision.

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  2. 2. tlmorrison 3:19 pm 08/4/2011

    I don’t know about what causes the improved sight, but the cognitive improvement could be coming from the fact that there is only a trace of caffeine in white chocolate, while there is significantly more caffeine in dark chocolate.

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  3. 3. dtfield 5:15 am 08/9/2011

    As the study author, I can say that the caffeine point is a good one. But we have now carried out a new study where the caffeine level is matched in the control condition, and the visual performance is still higher in the dark chocolate condition than the control condition. So caffeine levels in dark chocolate do not explain the visual result. (We did not measure the same cognitive performance measures in the new study, so I can’t comment on that.) We will publish the new study soon.

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  4. 4. dtfield 5:19 am 08/9/2011

    As the study author, I’d also like to emphasise that most dark chocolate contains much lower levels of cocoa flavanol than the chocolate we used in our study. The chocolate we used was deliberately produced in a way that maximises the flavanol level. Most dark chocolates have much lower flavanol levels, but they do of course contain a lot of calories and that’s unhealthy if you eat too much of it. It is hard to give advice about eating dark chocolate because nearly all manufacturers do not state the falvanol level on the packaging, and we know that the falvanol level varies a lot between different cocoa beans, different methods of production etc

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  5. 5. murphyod 1:12 pm 08/9/2011

    Thanks for the info, David! Can’t wait for the new study, I had a lot of fun writing up this topic. Your work is gaining a lot of admirers! Best of luck to you! =) Cheryl G. Murphy

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  6. 6. Neosteo 12:37 pm 08/12/2011

    Chocolate has over 300 chemicals compounds in it. Maybe just maybe this has something to do with the temporary heightened awareness of the senses that the subjects where experiencing.

    Its bad science if you ask me and no doubt the author is a chocolate fan!

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