Do Carbs Impact Eye Health?

A low carbohydrate diet has been associated with a host of positive outcomes related to cardiovascular and neurological health. But what few people realize is that such diets are also associated with eye health. A study published in the American Journal of Clinical Nutrition presents evidence that a lifetime of high-carbohydrate consumption significantly increases the chances of developing cataracts [1].

As the article points out, cataracts are the leading cause of blindness:

Results of a nationwide survey of middle-aged and older Americans revealed that blindness is among the most feared age-related impairments. Cataract is the leading cause of blindness worldwide. An estimated 20.5 million Americans aged 40 y (17.2% of that population) have cataract, 6.1 million (5.1%) have pseudophakia or aphakia, and it is predicted that those numbers will rise by 50% within 2 decades. Opacification, or lens clouding, begins months or even years before vision is affected. Consequently, strategies to prevent opacification hold promise for reducing this enormous public health burden.

The study showed that those women consuming on average over 200 grams of carbohydrates per day had over twice the likelihood of developing cataracts as those consuming less than 185 grams per day. 

Here is a case where if a little reduction in carb intake is good, a lot is probably better. So a low-carb diet with around 50 grams or less of carb a day would more than likely slow the development of cataracts even more.

Furthermore, a recent rodent study found a positive connection between a ketogenic diet and preventing glaucoma. Mice that were genetically destined to develop glaucoma were fed a diet of 90% fat and monitored for two months. The researchers found that the diet protected mice’s retinas from degeneration. These findings suggest that a ketogenic or low carbohydrate diet is also beneficial in the prevention and treatment of human patients with glaucoma [2].

Of particular note: in the earlier study mentioned about cataracts, the authors found that the quality of the carbohydrate, i.e., the glycemic index, had no effect on cataract development—it was simply the total amount.

The authors summarized:

In summary, carbohydrate intake was positively associated with the odds of early cortical opacities in middle-aged women. Because carbohydrate foods represent the main energy source for humans, understanding the potentially harmful effects of a high-carbohydrate diet on the lens is important and worthy of further study.

Indeed!

About Dr. Michael Eades
Dr. Michael Eades is a physician and co-author of 10 books in the fields of health, nutrition, and exercise over the last several decades—among them the New York Times bestseller Protein Power and its follow-up The Protein Power LifePlan that laid out one of the first nutritional concepts of a paleo lifestyle. Dr. Eades regularly writes articles at proteinpower.com and in his weekly email newsletter, The Arrow that incorporates his views on nutrition, medicine, critical thinking and more. Dr. Eades has appeared as a guest nutritional expert on hundreds of radio and television shows, including national segments on FOX, NBC, ABC, CBS, CNN, and MSNBC. He speaks at medical and scientific conferences, to the public, and to various lay organizations on the connection of diet and health, exercise, and the benefits of the low-carb, paleo, and keto diets. He and his wife (Mary Dan Eades, M.D.) are currently working on their next book, Protein Power 2.0, slated for publication in 2023.

References

1.  Chung-Jung Chiu, Martha S Morris, Gail Rogers, Paul F Jacques, Leo T Chylack, Jr, William Tung, Susan E Hankinson, Walter C Willett, Allen Taylor, Carbohydrate intake and glycemic index in relation to the odds of early cortical and nuclear lens opacities, The American Journal of Clinical Nutrition, Volume 81, Issue 6, June 2005, Pages 1411–1416, https://doi.org/10.1093/ajcn/81.6.1411
2. https://www.eurekalert.org/news-releases/574658