Researchers funded by the Biotechnology and Biological Sciences Research Council (BBSRC) have found that vitamin D reduces the effects of ageing in mouse eyes and improves the vision of older mice significantly. The researchers hope that this might mean that vitamin D supplements could provide a simple and effective way to combat age-related eye diseases, such as macular degeneration (AMD), in people.
The research was carried out by a team from the Institute of Ophthalmology at University College London and is published in the current issue of the journal Neurobiology of Ageing.
The retina's cells are very heavy energy users, heavier energy users than any other cell type in the body. I did not know that.
Professor Glen Jeffery, who led the work, explains "In the back of the eyes of mammals, like mice and humans, is a layer of tissue called the retina. Cells in the retina detect light as it comes into the eyes and then send messages to the brain, which is how we see. This is a demanding job, and the retina actually requires proportionally more energy than any other tissue in the body, so it has to have a good supply of blood. However, with ageing the high energy demand produces debris and there is progressive inflammation even in normal animals. In humans this can result in a decline of up to 30% in the numbers of light receptive cells in the eye by the time we are 70 and so lead to poorer vision."
We need cell therapies to replace tired eye blood vessels, rod cells, cone cells, and other retinal cells. The inflammation and decline in number of light receptive cells with age could be reversed and some day will be reserved. Faster please, as Glenn Reynolds likes to say.
The vitamin D reduced both inflammation and amyloid beta.
The researchers found that when old mice were given vitamin D for just six weeks, inflammation was reduced, the debris partially removed, and tests showed that their vision was improved.
The researchers identified two changes taking place in the eyes of the mice that they think accounted for this improvement. Firstly, the number of potentially damaging cells, called macrophages, were reduced considerably in the eyes of the mice given vitamin D. Macrophages are an important component of our immune systems where they work to fight off infections. However in combating threats to the aged body they can sometimes bring about damage and inflammation. Giving mice vitamin D not only led to reduced numbers of macrophages in the eye, but also triggered the remaining macrophages to change to a different configuration. Rather than damaging the eye the researchers think that in their new configuration macrophages actively worked to reduce inflammation and clear up debris.
The second change the researchers saw in the eyes of mice given vitamin D was a reduction in deposits of a toxic molecule called amyloid beta that accumulates with age. Inflammation and the accumulation of amyloid beta are known to contribute, in humans, to an increased risk of age-related macular degeneration (AMD), the largest cause of blindness in people over 50 in the developed world. The researchers think that, based on their findings in mice, giving vitamin D supplements to people who are at risk of AMD might be a simple way of helping to prevent the disease.
This result is consistent with earlier research on humans that found that higher blood vitamin D levels are associated with a lower risk of age-related macular degeneration. Also, higher vitamin D is associated with healthier blood vessels.
Some evidence exists that too much vitamin D increases risk of atrial fibrillation. But the levels associated with healthier blood vessels and lower AMD risk in humans are below those found to increase atrial fibrillation. So this makes me think there's some value in getting one's vitamin D levels tested and then supplement as necessary to keep one's blood vitamin D in the normal (41-80 ng/dl) range.
|Share |||Randall Parker, 2012 January 22 10:05 PM Aging Diet Eye Studies|