A recent study that found vitamin C and carotenoids to be protective against certain types of cataracts adds to the growing body of data on the relationship between nutrition and eye health. The results are published in the American Journal of Clinical Nutrition.

Evidence from the Nurses' Health Study

Researchers in Boston studied almost 500 women from the Nurses' Health Study cohort. The women were between the ages of 53 and 73, did not have diabetes, and were without previously diagnosed cataracts.

Nutrient intake was assessed using five food-frequency questionnaires collected during the 13- to 15-year period before eye examination, with the average intake from these five surveys used to define usual nutrient intake. Vitamin supplement use was also quantified, using seven questionnaires administered during this same time period.

Lens opacities were classified using the Lens Opacities Classification System III, with cortical opacities defined as grade >/= 0.5 and subcapsular opacities as grade >/= 0.3.

No significant associations between specific nutrients and odds of developing cataracts were identified in the full sample. However, associations were found between age and vitamin C, and between carotenoids and smoking status.

Vitamin C and age

In women younger than 60, a vitamin C intake of >/= 362 mg/day was associated with a 57% lower odds ratio of developing a cortical cataract than was an intake of < 140 mg/day (OR=0.43, 95% CI 0.2-0.93).

Vitamin C supplement use was also a factor, with longer duration of supplement use (>/= 10 years) associated with lower odds of developing cortical cataracts than with no supplement use (OR=0.40, 95% CI 0.18-0.87).

Carotenoids and smoking

In women who never smoked, total carotenoid intake in the highest intake quintile was associated with lower odds of developing posterior subcapsular cataracts compared with the lowest intake quintile (OR=0.19, 95% CI 0.05-0.68).

Applying the results

While the results of this study add to existing evidence that good nutrition, particularly with regard to antioxidant nutrients, may play a role in eye health, further studies are necessary to corroborate the results in larger groups of women, as well as in men.

The results of this study alone do not warrant recommendations for antioxidant supplementation to protect against cataracts, but they do suggest that eating a diet high in antioxidants, such as those found in brightly colored fruits and vegetables, may help prevent or delay age-related lens opacities.