Vitamin D has been studied extensively in relation to bone health as well as cancer. Now, a team from the University at Buffalo has discovered that vitamin D may play a significant role in eye health, specifically in the possible prevention of age-related macular degeneration, or AMD, among women who are more genetically prone to developing the sight-damaging disease.
The research team found that women who are deficient in vitamin D and have a specific high-risk genotype are 6.7 times more likely to develop AMD than women with sufficient vitamin D status and no high risk genotype.
This study does not prove cause and effect 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 a chronic disease that attacks the central part of the retina called the macula, which controls fine, detailed vision. The condition results in progressive loss of visual sharpness making it difficult to drive a car, read a book and recognize faces.
The exact cause of AMD is unclear, but factors such as genetics, family history, cigarette smoking, high blood pressure, excessive sunlight exposure, and a diet low in antioxidants are linked with a greater risk. (Antioxidants are thought to protect cells in the retina from the harmful effects of free radicals, unstable molecules formed from cigarette smoke, pollution and ultraviolet light.)
Researchers analyzed data compiled on 1,230 women ages 54 to 74 that participated in the Carotenoids in Age-related Eye Disease Study (CAREDS). CAREDS was conducted among participants at three of the centers: University of Wisconsin (Madison), the University of Iowa (Iowa City) and the Kaiser Center for Health Research (Portland, Oregon).
Macular degeneration has been found to be strongly associated with genetic risk. 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, fat and protein deposits that build up in the eye. The body sees this drusen as a foreign substance and attacks it. 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”, said the researcher.
Vitamin D shows promise for protecting against macular degeneration because of its anti-inflammatory and antiangiogenic properties. (Antiangiogenic refers to slowing the growth of new blood vessels, often seen in late stages of AMD.)
"Our study suggests that being deficient for vitamin D may increase one's risk for AMD, and that this increased risk may be most profound in those with the highest genetic risk for this specific variant in the CFH protein."
The study results, however, don’t mean people should run to the nearest drugstore to buy vitamin D supplements.
The message is not that achieving really high levels of vitamin D is good for the eye, but rather that having a deficient vitamin D level may be unhealthy for the eyes.
Although the odds of having AMD was higher in women who were deficient for vitamin D (below 12 ng/mL or 30 nmol/L), increasing vitamin D levels beyond 12 ng/mL did not further lower the odds of AMD.
Source: JAMA Ophthalmology, August 27, 2015.
All research on this web site is the property of Leslie Beck Nutrition Consulting Inc. and is protected by copyright. Keep in mind that research on these matters continues daily and is subject to change. The information presented is not intended as a substitute for medical treatment. It is intended to provide ongoing support of your healthy lifestyle practices.