Long-term intake of vitamins and carotenoids and odds of early age-related cortical and posterior subcapsular lens opacities.

Background: Proper nutrition appears to protect against cataracts. Few studies have related nutrition to the odds of developing cortical or posterior subcapsular (PSC) cataracts.
Objective: We assessed the relation between usual nutrient intakes and age-related cortical and PSC lens opacities.
Design: We studied 492 nondiabetic women aged 53-73 y from the Nurses' Health Study cohort who were without previously diagnosed cataracts. Usual nutrient intake was calculated as the average intake from 5 food-frequency questionnaires collected over a 13-15-y period before the eye examination. Duration of vitamin supplement use was determined from 7 questionnaires collected during this same period. We defined cortical opacities as grade > or = 0.5 and subcapsular opacities as grade > or =0.3 of the Lens Opacities Classification System III.
Results: Some lenses had more than one opacity. No nutrient measure was related to prevalence of opacities in the full sample, but significant interactions were seen between age and vitamin C intake (P = 0.02) for odds of cortical opacities and between smoking status and folate (P = 0.02), alpha-carotene (P = 0.02), beta-carotene (P = 0.005), and total carotenoids (P = 0.02) for odds of PSC opacities. For women aged <60 y, a vitamin C intake > or = 362 mg/d was associated with a 57% lower odds ratio (0.43; 95% CI: 0.2, 0.93) of developing a cortical cataract than was an intake <140 mg/d, and use of vitamin C supplements for > or = 10 y was associated with a 60% lower odds ratio (0.40; 0.18, 0.87) than was no vitamin C supplement use. Prevalence of PSC opacities was related to total carotenoid intake in women who never smoked (P = 0.02).
Conclusions: Our results support a role for vitamin C in diminishing the risk of cortical cataracts in women aged <60 y and for carotenoids in diminishing the risk of PSC cataracts in women who have never smoked.