Vitamin D supplements may have wide-ranging anti-ageing properties, including the preservation of eyesight, research suggests.
Middle-aged mice treated with the vitamin for six weeks underwent changes in their eyes that led to improved vision.
Levels of amyloid beta, a toxic protein linked to Alzheimer's disease and known to be a hallmark of ageing, were also reduced in the animals' eyes and blood vessels.
Although the research is still at an early stage, scientists believe it could have important implications for human health.
Boosting vitamin D intake may have broad anti-ageing effects and in particular help prevent loss of vision and blindness in older people, it is claimed.
Lead scientist Professor Glen Jeffery, from the Institute of Ophthalmology at University College London, said: "Finding that amyloid deposits were reduced in the blood vessels of mice that had been given vitamin D supplements suggests that vitamin D could be useful in helping to prevent a range of age-related health problems."
Age-related inflammation and damage to the eye's retina can lead to macular degeneration, the biggest cause of blindness in people over the age of 50 in the developed world.
The research findings are published in the journal 'Neurobiology of Aging'.
The UCL team injected one-year-old female mice with safflower oil containing 0.9 micrograms of vitamin D every three days. Another group received injections of vitamin-free safflower oil.
After six weeks, tests showed significant improvement in the vision of the treated mice.
Vitamin D treatment reduced numbers of cells called macrophages, which play a vital role in the immune system but can also trigger inflammation.
The remaining macrophages seemed to work in a more beneficial way, actively combating inflammation and clearing up cellular debris.
Deposits of amyloid beta in the eye were also lowered.
Accumulations of the toxic protein are believed to contribute both to age-related macular degeneration (AMD) and Alzheimer's.
Taking vitamin D supplements in the early stages of AMD "may prove a very simple and effective route to limit disease progression", the researchers wrote.
"Researchers need to run full clinical trials in humans before we can say confidently that older people should start taking vitamin D supplements, but there is growing evidence that many of us in the Western world are deficient in vitamin D and this could be having significant health implications." said Prof Jeffery.
"Anyone thinking about taking a vitamin supplement should consult their doctor," he added.