Increasing one's vitamin D levels may reduce the risk of illnesses that cause dementia, including Alzheimer's disease, according to international research led by the University of Exeter.

"Senile dementia and Alzheimer’s disease were both significantly higher in people with low levels of vitamin D, compared to those with normal levels, when tested up to six years before the onset of symptoms, scientists found," notes The Independent.

The research, published in Neurology, examined vitamin D levels in 1,659 Americans who were at least 65 years old and had no signs of dementia, heart disease or stroke at the study's onset. They were followed for six years, and researchers noted a 53 percent increased risk of dementia in those with moderate vitamin D deficiency, compared to those who had enough. Those with severe deficiency had double that risk: 122 percent increased risk for Alzheimer's.

"Our results confirm that vitamin D deficiency is associated with a substantially increased risk of all-cause dementia and Alzheimer's disease. This adds to the ongoing debate about the role of vitamin D in nonskeletal conditions," the researchers wrote.

“We expected to find an association between low vitamin D levels and the risk of dementia and Alzheimer’s disease, but the results were surprising — we actually found the association was twice as strong as we anticipated,” said David Llewellyn of the University of Exeter, in a written statement.

As many as 44 million people worldwide are believed to have dementia, and experts have repeatedly predicted that number will triple over the next half-century. For each person with dementia, the impact ripples to extended family, including spouses, children, siblings and others.

Forbes said the results "were unchanged after researchers adjusted for factors that could affect risk of dementia, such as smoking, alcohol use, as well as education."

The researchers cautioned that more study is needed before they can list vitamin D deficiency as a "cause" of dementia. But it's not the first study to find an association between the vitamin and cognitive decline.

An article by CBS News noted other known benefits: "Vitamin D is essential for maintaining bone health. It is also thought to moderate cell growth and help control immune function and inflammation. Vitamin D can be obtained through food, through the skin after exposure to sunlight and from supplements."

“Clinical trials are now needed to establish whether eating foods such as oily fish or taking vitamin D supplements can delay or even prevent the onset of Alzheimer’s disease and dementia,” Llewellyn said in background material.

Whether dietary changes or more sun exposure would help is unknown, Keith Fargo, director of scientific programs and outreach for the Alzheimer's Association, told WebMD. "We don't know if increasing vitamin D levels would decrease the risk of Alzheimer's."

Fargo recommended that people ''try to eat a brain healthy diet," including foods low in fat and cholesterol. Consistent physical activity and maintaining a healthy blood pressure are also important, he said.

The Alzheimer's Association helped fund the study, which included researchers from Angers University Hospital, Florida International University, Columbia University, the University of Washington, the University of Pittsburgh and the University of Michigan. Other financial support was provided by Mary Kinross Charitable Trust, the James Tudor Foundation, the Halpin Trust, the Age Related Diseases and Health Trust, the Norman Family Charitable Trust, and the National Institute for Health Research Collaboration for Leadership in Applied Research and Care South West Peninsula (NIHR PenCLAHRC).

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