Abstracted by Greg Arnold, DC, CSCS, January 16, 2012, from “Vitamin D rejuvenates aging eyes by reducing inflammation, clearing amyloid beta and improving visual function” printed online ahead of printed January 2, 2012 in Neurobiology of Aging. Posted June 19, 2012. r/km
No organ in the body has a higher rate of cell activity (metabolism) than the eye, specifically the retina (1). But this high rate of cell activity comes with a high risk of damage to the retina in the form of a buildup of amyloid beta proteins. The protein buildup decreases blood supply to the retina and leads to eye diseases like macular degeneration. This condition affects 11 million Americans at a cost of $51 billion per year. In addition, 733 million people worldwide experiencing “low vision” at a cost of $3 trillion per year (2).
Along with decreased blood supply in the eye comes increased levels of inflammation (3) that can decrease the number of cells in the eye by as much as 30% (4). As a result, ways to help minimize damage to the retina while decreasing inflammation are of primary importance to eye health. Now a new study in mice (8) suggests that vitamin D may benefit eye health.
In the study, 14 one-year old mice were injected every 3 days with either vitamin D (0.9 micrograms in 0.1 mL safflower oil) or placebo (just safflower oil) for 6 weeks (a total of 14 injections)*. By the end of the 6 weeks of injections, those in the vitamin D group had 39% lower levels of amyloid beta protein compared to the control group (2.3 vs. 3.2 x 106 integrated density) while levels of the inflammatory C3 protein (9) were 46% lower in the vitamin D group compared to the control group (3.4 vs. 2.3 x 106 integrated density).
The decreased amyloid beta and C3 protein levels also resulted in improved vision in the mice measured with an electroretinogram (10). By the end of the 6 weeks of injections, the mice in the vitamin D group had a 35% higher a-wave than the control group (25 vs. 18.5 microVolts), a sign of greater visual acuity in the vitamin D group.
For the researchers, “These results clearly demonstrate that vitamin D has a marked impact on aged eyes even when given for short periods” and recommend vitamin D supplementation in Americans due to research suggesting a vitamin D deficiency epidemic in the United States (11).
However studies need to be done at lower doses to assure that these improvements in mice are achievable in humans using reasonable amounts.
*Converting from injections in mice to orallly in humans involves several estimations. However using 0.025 micrograms of Vit D per IU and dividing by a conversion factor of 12.3 (See Understanding Nutrition- Extrapolation to Human Dose) and assuming absorption of 90%, and mouse weight of 20 grams compared to human weight of 80 Kg, the dose given is equivalent to 532,000IU per day compared to the RDA of 400 for human adults.
- Graymore, C., 1969. The Eye. Academic Press, New York, NY.
- “Facts on Macular Degeneration” – http://www.ahaf.org/macular/about/understanding/facts.html
- Chen, M. Immune activation in retinal aging: a gene expression study. Invest. Ophthalmol. Vis. Sci. 2010; 51, 5888–5896.
- Cunea, A. The ageing photoreceptor. Vis. Neurosci. 2007; 24,151–155.
- Seddon JM, Ajani UA, Sperduto RD, et al. Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. JAMA. 1994;272:1413-1420.
- Progression of age-related macular degeneration: association with dietary fat, transunsaturated fat, nuts, and fish intake. Arch Ophthalmol. 2003 Dec;121(12):1728-37.
- Reddy VN. SOD2 Protects against Oxidation-Induced Apoptosis in Mouse Retinal Pigment Epithelium: Implications for Age-Related Macular Degeneration. Invest. Ophthalmol. Vis. Sci. 2005 46: 3426-3434.
- Lee V. Vitamin D rejuvenates aging eyes by reducing inflammation, clearing amyloid beta and improving visual function. Neurobiol Aging 2011; online ahead of print 1/2/12.
- Anderson, D.H. A role for local inflammation in the formation of drusen in the aging eye. Am. J. Ophthalmol. 134, 411–431.
- “The Electroretinogram” – http://www.ncbi.nlm.nih.gov/books/NBK11554/
- Holick, M.F., 2005. The vitamin D epidemic and its health consequences. J. Nutr. 135, 2739S–2748S.