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Multi Use & Cataract Risk; Nutrients & Genetic Risk of AMD

2013 Findings for Nutrition & Ocular Health

Several studies with positive findings mark the end of 2013, emphasizing that dietary choices and smart supplementation can support our visual health.

The December issue of Staying Healthy covered two new studies: a meta-analysis suggesting the importance of consuming lutein and zeaxanthin to help forestall nuclear cataract (the most common type of age-related cataract), and a clinical trial which found that supplemental lutein, zeaxanthin and docosa-hexaenoic acid (DHA) improved macular pigment density in patients with early age-related macular degeneration (AMD).

This issue highlights two additional studies published late last year that are worthy of mention. One examines the role of certain nutrients in people who inherit a high genetic risk of developing AMD (1), while the other is a large-scale trial of multivitamin use and cataract risk (2).

Fish, Lutein-Rich Foods Protective for AMD

In the first study, a team of researchers from Australia, the Netherlands and the US combined data from two large population studies, the Rotterdam Study and the Blue Mountains Eye Study – large studies where people were followed for 15 years. The team wanted to examine whether nutrients could influence AMD development or progression in people with a high genetic risk of AMD based on two major genes (CFH and ARMS2).

Looking at the interplay between nature (one’s genetic make-up) and nurture (diet and lifestyle choices) may provide a better understanding of why some people with genetic risk for AMD develop the condition, while others don’t.

The results of their analysis suggest that greater consumption of lutein / zeaxanthin-rich foods and fish is protective against AMD in people with high genetic risk. Those with 2 or more risk alleles (different forms of a gene) who ate fish weekly were 46% less likely to have late AMD.

The high-risk group also benefited from regular consumption of lutein and zeaxanthin rich foods. Those eating the most of these two carotenoids had a 22% to 25% lower risk for early AMD and any AMD, compared with those eating the least. These dietary associations were not seen in low risk groups – those with no risk allele or only one risk allele.

Even if you’re dealt a poor genetic hand, there are steps you can take to reduce your chance of developing AMD: include fish and green leafy vegetables in your diet, exercise and watch your weight, don’t smoke, and get regular eye exams.

A Daily Multi Lowers Cataract Risk

Harvard researchers have reported the final results for cataract and AMD from the multivitamin part of the Physicians’ Health Study II (PHS II). PHS II was a long- term trial that included over 14,000 healthy middle-aged men, all physicians.

The multivitamin portion of the trial ended in 2011, and the researchers reported that taking a daily multi lowers the risk of cancer, though not cardiovascular disease. The trial also evaluated the effects of a multi on the prevention of eye disease (cataract and AMD), and cognitive function.

The results showed that the multivitamin group had a significant 9% lower risk of cataract over the 11-year course of treatment. Although the risk reduction is modest, cataract is so common that even a modest reduction in risk would have a large public health impact. There was no significant benefit or harm of multivitamin supplementation on visually significant (later stage) AMD.  Still to be reported are the results for cognitive function and daily multi supplementation.

References

1. Wang Jie Jin, et al. Genetic susceptibility, dietary antioxidants, and long-term incidence of age-related macular degeneration in two populations. Ophthalmology Nov 28, 2013 [Epub ahead of print].
2. Christen WG, et al. A multivitamin supplement and cataract and age-related macular degeneration in a randomized trial of male physicians. Ophthalmology Nov 20, 2013 [Epub ahead of print].