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Data show benefit for reducing cataract risk

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Vitamin supplements may indeed reduce the risk for developing cataracts, suggests recent findings from the Physicians’ Health Study, a large long-term research project.

The study randomised 14,641 US male physicians aged 50 years or older to daily use of a multivitamin/mineral supplement (“MVI”; Centrum Silver) or placebo. After a mean follow-up of 11.2 years, the risk of cataract was significantly reduced in the supplement group compared with the controls (p=.04). There were 872 cataracts in the multivitamin group and 945 cataracts in the placebo group (hazard ratio [HR], 0.91; 95 per cent confidence interval [CI], 0.83-0.99; P = 0.04). More cases of visually significant AMD occurred in the vitamin group, but the between-group difference was not statistically significant.

Emily Chew MD, deputy clinical director, National Eye Institute, and lead investigator of the Age-Related Eye Disease Study (AREDS) and AREDS2, spoke to EuroTimes about the data.

She emphasised the need to consider the randomised-controlled clinical trial design of the Physicians’ Health Study.

“The nine per cent reduction in cataract risk may seem small, but it would be important for reducing the burden from this common condition. However, the impact of this particular multivitamin on cataract and visually significant AMD needs further verification prior to implementation because such analyses are often thought of as hypotheses generating,” said Dr Chew.

In addition, she noted the benefit on cataract risk is consistent with other published data. The placebo-controlled Italian-American Clinical Trial of Nutritional Supplements and Age-Related Cataract, which investigated the effect of multivitamin treatment on cataract development or progression as a primary objective, found their use significantly decreased lens events. Because the results were mixed, nuclear cataract events were significantly decreased but posterior subcapsular cataract risk was significantly increased, the investigators made no treatment recommendations.

AREDS observational data also support multivitamin prevention of cataract. In a logistic regression analysis adjusting for propensity score and other variables, Centrum significantly reduced lens opacity. Again, the benefit was mostly for nuclear cataract.

Dr Chew said the absence of benefit of vitamin supplement treatment on risk of visually significant AMD in the Physicians’ Health Study is not surprising considering the supplement’s ingredients. Compared with the AREDS formulation, which significantly reduced the risk for progression to advanced AMD in those at high risk, the current study’s supplements contain much lower levels of antioxidant and neither copper or zinc, she explained.

“In the interest of optimising ocular and general health and until more information is available, it is important to recommend that patients have a healthy diet that is replete with fish and green vegetables,” said Dr Chew.

“For patients at risk for developing AMD, based on the results of AREDS and AREDS2, we would suggest using the AREDS formulation and considering using lutein/zeaxanthin in place of beta-carotene.”

The study results appeared recently in the journal Ophthalmology. (2014;121(2):525-34].

Emily Chew: echew@nei.nih.gov

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