Can fruits, vegetables lower cataract risk?

A diet rich in antioxidant-laden fruits and vegetables may lessen the risk of cataracts according to the latest research that reinforces how proper nutrition may hedge against age-related eye disease risk.

"For ocular nutrition, the rules don’t really change—more fruit and veggies, and the more raw, or non-prepared, the better."

Published in the American Journal of Clinical Nutrition, a meta-analysis of 20 clinical studies determined that most vitamins and carotenoids were significantly associated with reduced risk of age-related cataracts and there appeared greater dose responses for lutein and zeaxanthin, vitamin C and vitamin A. Such findings add to the current body of evidence that antioxidant vitamins may decrease the progression of cataracts or age-related macular degeneration (AMD).

By age 80, more than half of all Americans either have a cataract or have had cataract surgery. Caused by proteins that clump together over time, cataracts gradually cloud the normally clear lens and reduce visual clarity. While symptoms of early cataract may be improved with new glasses or lenses, surgery is warranted when vision loss interferes with daily activities.

With an increasingly aging population, the number of people awaiting cataract surgery has risen dramatically with more than 2 million procedures each year, researchers say. That said, even a 10-year delay in cataract onset could reduce the number of people requiring surgery by half, which is why researchers from China and the University of South Australia investigated oxidative damage and nutrition's mitigating effect.

Per the study, researchers performed a meta-analysis of 20 randomized control trial or cohort studies to assess individual dietary vitamin or carotenoid intake and cataract risk in subjects 40 years or older. Their findings suggested "significant inverse associations between intakes of most dietary vitamins and carotenoids" and cataract risk in cohort studies, while randomized control trials determined that vitamin E and beta-carotene supplementation did not significantly reduce cataract risk.

"Although we found that increasing vitamin and carotenoid intake could lead to a lower risk of (age-related cataract), it was estimated that the current consumption of antioxidants in the United States and many European countries was still below the recommended level for the prevention of age-related eye diseases," the study concluded.

Researchers suggested clinicians might continue efforts to educate patients on the importance of proper nutrition, such as the consumption of citrus fruits and dark-green leafy vegetables, to address the public health threat.

Eating for your eyes

Nutrition is one promising means of preventing or delaying the progression of age-related eye diseases. In fact, the large-scale Age-Related Eye Disease Studies (AREDS and AREDS2) conducted by the National Eye Institute (NEI) concluded that antioxidant vitamins and minerals reduced the risk of developing advanced AMD by about 25 percent and reduced risk of vision loss by 19 percent. Moreover, numerous studies found that higher intakes of vitamin C reduced risk for nuclear and cortical cataracts.

Given these associations, doctors of optometry may want to consider discussing healthy nutrition options with their patients. The National Cancer Institute and U.S. Department of Agriculture recommend five servings of fruits and vegetables daily to provide more than 100 mg of vitamin C. However, most Americans aren't meeting these recommendations. Those recommended daily allowances, include:

Vitamin C
90 mg/day for men
75 mg/day for women
Additional 35 mg/day for smokers

Vitamin E

22 IU (15 mg)/day from nutrition
33 IU (30mg)/day from synthetic sources

"For ocular nutrition, the rules don't really change-more fruit and veggies, and the more raw, or non-prepared, the better," said Daniel Bintz, O.D., AOA Health Promotions Committee member. But, proper nutrition is only one part of a healthy eyes equation. Regular, in-person comprehensive eye exams are still the most important part of preventive eye health care.

Want cataract resources? Access AOA's clinical practice guideline, Care of the Adult Patient with Cataract and its easy-to-use, 6-page quick-reference guide to navigate patient care options, while also reinforcing the beneficial role doctors of optometry play in the multidisciplinary care of cataract patients.

April 9, 2019

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