Eyeworld

EW RETINA 114 by Maxine Lipner EyeWorld Senior Contributing Writer with a chronic disease and changed their behavior, which made it look as if their vitamin D levels were higher than they had been during the majority of their life," she said. "For these reasons we didn't look at the older women." At increased risk In those under age 74, investiga- tors found increased risk for AMD in women who were deficient in vitamin D. "What we saw is women tended to not have increased odds of AMD until their 25-hydroxyvitamin D levels were deficient, then their odds of getting AMD increased," Dr. Millen said. Vitamin D levels of less than 30 nanomoles per liter did not seem to be good for bones or for eyes. Eyeing vitamin D levels in connection with disease development T here appears to be many ways that adequate nutri- tion can support eye health. Having sufficient vitamin D status may be one of them, according to Amy Millen, PhD, asso- ciate professor, Department of Epide- miology and Environmental Health, School of Public Health and Health Professions, University at Buffalo, Buffalo, N.Y. In a study published in the October 2015 issue of JAMA Ophthalmology, investigators found that women who were deficient in vitamin D might be more vulnerable to age-related macular degeneration (AMD). In particular, those without adequate vitamin D who also carried a high-risk genotype for comple- ment factor H had a 6.7 greater risk of developing the disease, Dr. Millen reported. This was something that Dr. Millen's group had previously con- sidered. "Our research group had done 2 previous papers in this area," Dr. Millen said. In this earlier work looking at people's vitamin D levels in conjunction with their AMD status, the group found a protective association, she noted. However, a limitation to the existing work is their cross-sectional design, investi- gating associations between vitamin D status and AMD at only 1 point in time. The impetus for this initial work came from mounting evidence suggesting that inflammation is involved in developing macular degeneration and that vitamin D has anti-inflammatory properties, Dr. Millen explained. "We know vitamin D to be related to bone health and involved in the uptake of calcium and calcium homeostasis," she said, adding that evidence has been building that vitamin D plays other roles in the body. Intrigued by vitamin D Part of what has spurred interest is the fact that vitamin D receptors have been found in other areas besides the bones, kidneys, and intestines, Dr. Millen explained. "People question why the vitamin D receptor is found in other parts of the body," she said. "Also, there has been research showing that vitamin D has anti-inflammatory effects and is involved in angiogenesis." In addition to new blood vessel forma- tion in cancer cases, such neovascu- larization plays a role in advanced macular degeneration. As part of the recent study, in- vestigators analyzed data on approx- imately 1,700 women ages 54 to 74 who took part in the Carotenoids in Age-Related Eye Disease Study (CAREDS); CAREDS is ancillary to the larger Women's Health Initiative (WHI) investigation. "[The women] came in for a study visit and we took eye photos. We also assayed stored blood drawn 6 years prior to CAREDS at a previous WHI study visit for 25-hydroxyvitamin D," Dr. Millen said. "This is a biomarker for vitamin D status, and it reflects D that's coming from sunlight and from foods and supplements." In the study, investigators de- fined deficient levels of vitamin D as those less than 30 nanomoles per li- ter. This is the level that the Institute of Medicine defines as being defi- cient with respect to bone health, Dr. Millen explained, adding that investigators went with this because they didn't have any criteria as to what would be considered deficient for macular degeneration. One group not included here was women over age 75. That's because no protective level of blood serum levels of vitamin D was seen in this older age group, Dr. Millen explained. "We think they may have had competing risks and died from other diseases or were diagnosed On the AMD plate Those who are deficient in vitamin D may be more prone to develop AMD. Source: National Eye Institute March 2016 continued on page 117

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