A/Prof Amy Millen’ team found women who are deficient in vitamin D and have a specific high-risk genotype are 6.7X more likely to develop AMD than women with sufficient vitamin D status and no high risk genotype.
“This is not a study that can, alone, prove a causal association, but it does suggest that if you’re at high genetic risk for AMD, having a sufficient vitamin D status might help reduce your risk.”
Macular degeneration is characterized by the deterioration of the macula, a small part of the central retina where the eye’s photoreceptors (rods and cones) are most highly concentrated. The leading cause of legal blindness, macular degeneration affects more than 10 million Americans—more than cataracts and glaucoma combined—according to the American Macular Degeneration Foundation. The disease affects a person’s central vision, which is needed for common tasks such as reading and driving.
METHOD: Researchers analyzed data compiled on 1,230 women ages 54 to 74 who participated in the Carotenoids in Age-related Eye Disease Study (CAREDS), which is an ancillary study of the Women’s Health Initiative (WHI) Observational Study (OS). The WHI OS is a major National Institutes of Health-funded research program aimed at addressing the most common causes of death, disability and poor quality of life in postmenopausal women. Vitamin D status was analyzed via serum samples for a vitamin D biomarker, 25-hydroxyvitamin D [25(OH)D], which provided a glimpse into vitamin D intake through all sources: diet, supplements and sunlight.
“Macular degeneration has been found to be strongly associated with genetic risk,” Millen says. Among many genes linked to AMD, one of the strongest is a specific genetic variant (Y402H) in the complement factor H gene, called CFH for short. This gene codes for the CFH protein that is involved in the body’s immune response to destroy bacteria and viruses.
Inflammation is believed to be involved in the development of macular degeneration.
“People who have early stage AMD develop drusen, lipid and protein deposits that build up in the eye. Your body sees this drusen as a foreign substance and attacks it, in part via the complement cascade response,” explains Millen. “CFH is one of the proteins involved in this response. We see more AMD in people who have certain variants in the gene which encodes a form of this CFH protein that is associated with a more aggressive immune response.”
MOA: Vitamin D shows promise for protecting against macular degeneration because of its anti-inflammatory and antiangiogenic (new blood vessels, often seen in late stages of AMD) properties; .
>>Although the odds of having AMD was higher in women who were deficient for vitamin D, with 25(OH)D levels below 12 ng/mL (30 nmol/L), increasing vitamin D levels beyond 12 ng/mL did not further lower the odds of AMD to any meaningful extent. http://www.buffalo.edu/news/releases/2015/08/032.html
Amy Millen, associate professor of epidemiology and environmental health in the University at Buffalo’s School of Public Health and Health Professions, is lead author on a paper published Aug. 27 in JAMA Ophthalmology. – See more at: http://www.buffalo.edu/news/releases/2015/08/032.html#sthash.KA49srdH.dpuf
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