Recent Research on Diet, Antioxidants & Cataract

Diet & Antioxidants 'Eyed' for Cataract

A cataract is a clouding of the eye's lens that eventually interferes with vision, and requires surgical removal for vision to be restored. Age, genetics and the environment - as well as injury, trauma and medications such as corticosteroids - are all factors that may contribute to cataract development, a common condition in people over age 65. Results from recent studies suggest that your intake of antioxidant nutrients, as well as the type of carbohydrates that you eat, may also play a role.

Antioxidants Reduce Cataract Risk over Time

Antioxidants may help prevent age-related cataracts, according to a new study published in the American Journal of Clinical Nutrition (1).

The Blue Mountains Eye Study included 3,654 people over 48 years old. Initially, each participant had an eye exam and their dietary intake and antioxidant supplement use including beta-carotene; zinc; and vitamins A, C and, E was assessed.

People with the highest vitamin C intake from diet and supplements had a significantly reduced cataract risk after 10 years compared with those consuming less.

Those with above-average intakes of combined antioxidants, including vitamins C and E, beta-carotene, and zinc, also had a reduced cataract risk compared with those consuming fewer antioxidants.

The authors point out that the study participants overall ate lots of fruits and vegetables and had "fairly healthy diet habits." Around 1/3 of the people were taking vitamin supplements at the baseline exam, with a median vitamin C intake of 500 mg among supplement users."

Lutein and Zeaxanthin are Important Too

Results of a prospective study from Harvard Medical School add to the body of evidence suggesting that lutein, zeaxanthin and vitamin E may also help delay cataract formation (2). Lutein and zeaxanthin are present in the human lens, where they filter out harmful blue light. In this study, dietary intake was assessed in over 35,000 women health professionals who were free of cataract. Information was gathered on the women's antioxidant intake from food and supplements, and they were followed for about 10 yrs. Women with the highest daily intake of lutein and zeaxanthin (6.7 mg, on average), cut their risk of developing cataract by 18% compared to those eating the least (about 1.2 mg a day).

For vitamin E, a 14% risk reduction was noted in the group with the highest intake overall. Those in the highest group consumed a mean of about 260 IU daily from food and supplements, while those in the lowest group got an average of 4-5 IU a day.

Make Your Carbohydrates the Complex Type

The glycemic index (GI) is a measure of how quickly carbohydrates raise blood sugar levels. In general, complex carbs like whole grains, brown rice and cereals raise blood sugar levels more slowly than sugary and processed foods like white breads. Several studies indicate that high GI diets raise the risk for early AMD, and that low GI patterns might be protective for nuclear cataracts, the most common cataract type (3,4).

Researchers from Tufts think that eating too many of the "fast" carbs can cause 'double trouble'. First, proteins that are directly needed for the visual function of the lens and retina may be damaged. Secondly, this eating pattern may also cause indirect damage by compromising pathways that usually identify and remove those damaged proteins.

The take-home message from all of this research is to make your diet high in antioxidant-rich produce and to eat sugary and processed foods infrequently.

References

1. Tan AG, et al. Antioxidant nutrient intake and the long-term incidence of age-related cataract: the Blue Mountains Eye Study. Am J Clin Nutr 87:1899-905, 2008.
2. Christen WG, et al. Dietary carotenoids, vitamins C and E, and risk of cataract in women: A prospective study. Arch of Ophthalmol 126:102-109, 2008.
3. Chiu C-J, et al. Long-term dietary carbohydrate intake, glycemic index and odds for early nuclear and cortical lens opacities. Am J Clin Nutr 81:1411-6, 2005.
4. 4. Chiu C-J, et al. Association between dietary glycemic index and age-related macular degeneration in nondiabetic participants in the Age-Related Eye Disease Study. Am J Clin Nutr 86:180-88, 2007.