Dietary supplements of vitamin D3 may boost visual function in lab mice, suggests a new study from the UK with potential implications for the eye health market.
The sunshine vitamin was associated with a reduction in the accumulation of amyloid beta, said to be a risk factor for age-related macular degeneration (AMD), the leading cause of blindness in the over 50s, report researchers from University College London’s Institute of Ophthalmology.
“Given the small size of the mouse cone population, the effect of vitamin D3 on their response is surprisingly large,” they wrote in Neurobiology of Aging .
“In humans, the central retina, which represents the region of greatest visual acuity, is populated purely by cones and is the targeted region in age related macular degeneration (AMD). Hence, in this respect, vitamin D3 treatment may have a more significant impact on the aging human retina and its visual function than that in rodents.”
The macula is a yellow spot of about five millimeters diameter on the retina. As we age, levels of the pigments in the macula decrease naturally, thereby increasing the risk of age-related macular degeneration (AMD). The yellow color is due to the content of the carotenoids lutein and zeaxanthin, which we derive from the diet.
These compounds are the only carotenoids capable of filtering the harmful blue light than can damage cells in the eye, the rods and the cones.
A thin macular pigment can allow the blue light through and destroy the cells. Maintaining high levels of both carotenoids, and therefore the macular pigment, is a valid approach to maintaining eye health and reducing the risk of AMD.
According to the researchers from University College London: “The outer retina has the highest metabolic demand in the body. With age, the interface between the outer retina and its blood supply becomes less permeable due to the development of deposits including amyloid beta.”
In order to investigate if vitamin D may benefit retinal health, the researchers supplemented the diets of lab-mice for six weeks and found that the vitamin was associated with a significant reduction in inflammation in the retina and reductions in the levels of amyloid beta.
The vitamin was also associated with significant reductions in the number of macrophages in the retina, a mark of chronic inflammation, said the researchers.
“Given the positive results presented here it is probably that vitamin D3 supplementation in early disease stages may prove a very simple and effective route to limit disease progression,” they added.
Source: Neurobiology of Aging
Volume 33, Issue 10, Pages 2382-2389, doi: 10.1016/j.neurobiolaging.2011.12.002
“Vitamin D rejuvenates aging eyes by reducing inflammation, clearing amyloid beta and improving visual function”
Authors: V. Lee, E. Rekhi, J. Hoh Kam, G. Jeffery