Nutritional Effect on Age-Related Cataract Formation and Progression

Ruti Sella; Natalie A. Afshari

Disclosures

Curr Opin Ophthalmol. 2019;30(1):63-69. 

In This Article

Interventional Studies: Contradicting Results

Many interventional randomized controlled trials (RCTs) have evaluated the efficacy of multivitamins/specific nutrient supplement on the risk of cataract in the past decade, with mixed results. Among which, the VECAT (Vitamin E, Cataract and Age-related Maculopathy Study),[22] the AREDS,[23] the AREDS2,[24] the ATBC (Alpha-Tocopherol Beta-Carotene study)[25] found no evidence that supplementary vitamins decrease the risk of ARC. The Linxian[26] and REACT (Roche European American Cataract Trial)[27] found efficacy for specific nutrition supplements in subgroups of patients. The AREDS2[24] study concluded that daily supplementation with lutein/zeaxanthin (carotenoids) had no overall effect on rates of cataract surgery or vision loss (hazard ratio 0.96, P = 0.54). The limitations of this study, however, include its relatively well nourished study population, which may mask its effect over patients with very low dietary intake of carotenoids. Moreover, in both AREDS and AREDS2, a multivitamin (Centrum) was given as a supplement at baseline for 80% of the participants, which could already have a protective effect on cataract progression. The protective effect of Centrum was indeed evaluated in the Italian-American Clinical Trial of Nutritional Supplements and Age-Related Cataract (CTNS)[28] and the Physicians' Health Study (PHS) II,[29,30] which documented a lower incidence of nuclear sclerosis cataract (34 and 13% risk reduction, respectively). The CTNS, however, found a higher risk for posterior subcapsular cataract in the multivitamin arm (hazard ratio 2.00, P = 0.001).[17,28]

It is important to remember that biochemical evidence point at difficulties in regressing the process of protein aggregation once it has already started.[19,31] The age of participant at intervention, the lens status at baseline and the length of intervention can all possibly impact these studies results. None of the above studies are, therefore, enough to issue a clear recommendation of multivitamin supplement for the prevention of cataract progression. In addition, the patient sex may be of importance. Lately, the mRNA expression of aquaporin 8 and glutathione peroxidase was shown to be different in men and women.[32] The correlation between the two is responsible for the way oxidative stress in the aqueous humor affects the lens after the intake of antioxidant supplements, as previously shown with a lutein-containing supplement.[33] Therefore, women and men's lenses may react differently to such supplements and studies should account for it.

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