Vitamin D could reduce the risk of dementia by a third
Vitamin D may reduce the risk of dementia by up to a third, a study has suggested.
Researchers at Tufts University in America looked at levels of vitamin D in 290 adults in the Rush Memory and Ageing Project, a long-term study of Alzheimer's that began in 1997.
The team looked at vitamin D levels in four regions of the brain. Two were linked to Alzheimer’s - one known to be involved in dementia, and another believed to not be linked to cognitive decline with age.
They found that vitamin D was present in all four regions and people with more of it had better cognitive function.
“Higher brain [vitamin D] concentrations were associated with a 25 per cent to 33 per cent lower odds of dementia or mild cognitive impairment at the last visit before death,” wrote the scientists in their paper.
However, the levels of vitamin D in the brain did not associate with any of the physiological markers associated with Alzheimer's disease when the brains were dissected after death.
These included amyloid plaque build-up, Lewy body disease, or evidence of chronic or microscopic strokes.
The scientists said that more work is needed to fully understand the role of vitamin D in the brain and how extensive its protective effect may be.
Brief exposure to sunlight provides a dose
“Higher brain vitamin D concentrations were associated with better cognitive function prior to death,” added the scientists.
“Additional research is needed to clarify the specific mechanisms underlying this potentially protective relationship.”
It is estimated that some 55 million people in the world have dementia. With this number expected to increase, researchers are looking to better understand what causes the condition in order to develop treatments to slow or stop the disease.
Fatty fish and fortified drinks, such as milk or orange juice, contain vitamin D. Brief exposure to sunlight also provides a dose of vitamin D.
Vitamin D supports many functions in the body, including immune responses and maintaining healthy bones.
Sarah Booth, senior author and director of the Jean Mayer USDA Human Nutrition Research Centre on Ageing at Tufts, said: “This research reinforces the importance of studying how food and nutrients create resilience to protect the ageing brain against diseases such as Alzheimer's disease and other related dementias.”
However, the researchers warned people not to take large doses of the sunshine vitamin as a preventive measure.
The NHS recommends that during the autumn and winter, everyone - including pregnant and breastfeeding women - should consider taking a daily supplement containing 10 micrograms of vitamin D.
“We now know that vitamin D is present in reasonable amounts in human brains, and it seems to be correlated with less decline in cognitive function,” lead author Dr Kyla Shea, from the Friedman School of Nutrition Science and Policy at Tufts, said.
“But we need to do more research to identify the neuropathology that vitamin D is linked to in the brain before we start designing future interventions.”
The findings are published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.
A study on half a million Britons found that ethnic minorities in Britain are suffering from vitamin D deficiency.
People with darker skin have more melanin and this inhibits the vitamin D mankind process from sunlight, with white people needing less sunlight to make enough of the vitamin.
More than half (57 per cent) of Asian people are “severely deficient” in vitamin D during the darker months of winter and spring, the data showed.
This percentage rises to 51 per cent in the summer and for black people, the figure is 38.5 per cent for the darker months and 30.8 per cent for the lighter times of the year.
Studies have also found it is good for cognitive performance in later life, with one paper finding that those over-60 with vitamin D deficiency declined mentally at a rate three times faster than those with adequate levels.
