Vitamin D associated with reduced risk of eye degeneration
Jun0820113:03 p.m.
High levels of vitamin D associated with reduced risk of developing early age-related macular degeneration
Age Related Macular Degeneration, or AMD, is the most common cause of blindness in people over the age of 50 in the UK. Previously I have written a lot about omega 3 fatty acids in relation to AMD, now a new study (1) published in the Archives of Ophthalmology has found that high levels of vitamin D in the bloodstream appear to be associated with a decreased risk of developing early age-related macular degeneration among women younger than 75 years.
A new study published in the Archives of Ophthalmology has found that high levels of vitamin D in the bloodstream appear to be associated with a decreased risk of developing AMD (3).
To recap from previous posts: The macular is the light sensitive area in the centre of the retina that controls visual field and the ability to see colours. AMD is caused by the deterioration of the macular. As this happens the peripheral, outer, vision remains intact as the centre field of vision becomes slowly blurry, grey or filled with a large black spot. Two forms of AMD exists: the dry form which develops slowly, accounting for 90% of all cases; and the wet form which causes rapid deterioration of central vision.
The exact causes of AMD are unknown although free radical damage, where unstable oxygen molecules damage the eye cells, is strongly implicated. Tobacco smoke and sun exposure can increase the level of free radicals in the body and both are a risk for AMD. High blood pressure and diabetes are also risk factors as these conditions can limit blood flow to the eyes.
The scientists (1) conducting this study wanted to look at the relationship between blood levels of vitamin D (serum 25-hydroxyvitamin D (25[OH]D)) and the prevalence of early age AMD in over 1000 women. It is noted in the research paper that “Serum 25(OH)D is the preferred biomarker for vitamin D status, as it reflects vitamin D exposure from both oral sources and sunlight.” (1)
The initial (1) analysis found that no significant relationship was found between vitamin D status and early or advanced AMD. However, when further analysis was done it was found that in the (968) women who were younger than 75 years old higher levels of serum vitamin D was associated with a significantly decreased risk of early AMD, in women 75 years and older (319), higher levels were associated with only a borderline statistically significant increased risk (1).
It was also found (1) that among women younger than 75 years, intake of vitamin D from foods and supplements was related to decreased risk of early AMD but no relationship was observed with self-reported time spent in direct sunlight. Women who consumed the most vitamin D (from food and supplements) had a 59% decreased risk of developing early AMD compared with women who consumed the least vitamin D. The top food sources of vitamin D in the sample were milk, fish, fortified margarine and fortified cereal. The authors conclude that (2)”This is the second study to present an association between AMD status and 25(OH)D, and our data support the previous observation that vitamin D status may potentially protect against development of AMD,” “More studies are needed to verify this association prospectively as well as to better understand the potential interaction between vitamin D status and genetic and lifestyle factors with respect to risk of early AMD.”
As stated this is just an association study and more research is needed before any firm conclusions can be drawn as to whether vitamin D can protect against the development of AMD. As you can see from all my previous posts on vitamin D there is no set recommendation for daily supplement use and it is likely that many people in the UK have low blood levels of this important vitamin. If you decide to take vitamin D supplements it is always best to check with your medical doctor first, especially if you are considering high doses (over 2000iu daily).
(1) Millen AE et al. 2011. Vitamin D Status and Early Age-Related Macular Degeneration in Postmenopausal Women. Archives of Ophthalmology. 129 (4): 481-489
(2) Press release. JAMA and Archives Journals (2011, April 11). High levels of vitamin D appear to lower risk of age-related macular degeneration in young women. ScienceDaily. Retrieved April 12, 2011, from http://www.sciencedaily.com¬ /releases/2011/04/110411163817.htm
(3) Image courtesy of Jeroen van Oostrom
Written by Ani Richardson
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