Healthy Eating Lowers Cataract Risk in Women

Dietary Components and Cataract Risk

Individual components of the diet have been associated with cataract risk over the past few decades. Antioxidants, for example, may lower risk for nuclear cataract by lowering oxidative stress or systemic inflammation (which can lead to oxidative stress). Having high intakes or blood levels of lutein and zeaxanthin and the use of multivitamin supplements have been most consistently related to lower risk for cataract. Less consistently, high dietary intake or blood levels of vitamins C and/or E have been associated with reduced risk.

A few studies have also associated other dietary components with lower risk for nuclear cataract or cataract extraction, including high intake of long-chain omega-3 fatty acids or low intake of refined carbohydrates (as indicated by a low glycemic index score). Only one previous study has directly evaluated the overall impact of a healthy diet on the occurrence of cataract. In that study, adherence to a Healthy Eating Index over a 10-year period was linked to a lower risk for early nuclear lens opacities (1).

The Carotenoids in Age-Related Eye Disease Study (CAREDS), part of the Women’s Health Initiative (WHI), previously found that high intake and blood levels of lutein and zeaxanthin lowered the risk for nuclear cataract in this cohort. CAREDS researchers now report that an overall healthy dietary pattern is related to a low prevalence of nuclear cataract (2).

Study Design

Presence of nuclear cataract was determined from slit-lamp photographs and self-reports of cataract extractions were assessed in 1,808 CAREDS participants. Scores on the 1995 Healthy Eating Index, which reflect adherence to 1990 guidelines, were assigned from responses to food frequency questionnaires at the WHI baseline.

Results

Having a high Healthy Eating Index score was the strongest predictor of low prevalence of nuclear cataract among numerous risk factors examined. The multivariate-adjusted odds ratio for high vs. low quintile for diet score was 0.63 (95% confidence interval, 0.43-0.91).

Higher prevalence of nuclear cataract was also associated with other modifiable factors (smoking and marked obesity) and non-modifiable factors (having brown eyes, myopia, and high pulse pressure).

Comments

Healthy Eating Index scores in the highest quintile were associated with a 37% lower risk for nuclear cataract after adjusting for non-dietary risk factors. These women ate diets that were lower in fat, saturated fat and sodium, and higher in lutein and zeaxanthin, vitamins C and E, and all other vitamins and minerals compared with women whose overall scores were in the lowest quintile. The authors conclude that “eating foods rich in a variety of vitamins and minerals may contribute to postponing the occurrence of the most common type of cataract in the U.S”.

While there is a large body of observational studies linking multivitamin use with lower risk of nuclear cataract, no association was found in the present study. The lack of a protective association could have resulted from the relatively healthy diets of the women sampled, according to the authors. It is also possible that multi-vitamins may protect against nuclear cataract only in people who have poor diets.

If that is the case, many Americans could potentially benefit from a multi-vitamin supplement to ensure adequate micronutrient intake. A newly published study (3) which examined the dietary habits of over 16,000 individuals found that more than 80% of those 70 and older, and more than 90% of all other groups of both sexes, consumed too many calories from fats, added sugars and alcohol. Nearly everyone failed to meet recommendations for dark green and orange vegetables, and whole grains.

References

1. Moeller SM, et al. Overall adherence to the dietary guidelines for Americans is associated with reduced prevalence of early age-related nuclear lens opacities in women. J Nutr 134:1812-1819, 2004.
2. Mares JA, et al. Healthy Diets and the Subsequent Prevalence of Nuclear Cataract in Women. Arch Ophthalmol128:738-749, 2010.
3. Krebs-Smith SM, et al. Americans do not meet federal dietary recommendations. J Nutr 140:1832-38, 2010.