A new study published in Neurology strengthens the connection between vitamin D and dementia risk, including Alzheimer’s disease. An international team of researchers led by Dr. David J. Llewellyn of the University of Exeter Medical School followed over 1,500 healthy elderly people for nearly six years and found that those with persistently low levels of vitamin D were up to 2.4 times more likely to develop Alzheimer’s compared to people with normal vitamin D levels. The commonly accepted definition of vitamin D deficiency is a level below 30 nanomoles per liter, although this study used a level below 50 as a threshold.
While this study strengthens the association between low vitamin D and dementia risk, the researchers could not definitively rule out a phenomenon called “reverse causality,” meaning it is possible that low vitamin D levels did not cause the dementia and were associated with an increased risk in certain people for other reasons.
The Cognitive Vitality report on vitamin D includes our ratings and an overview of all the available evidence on its possible role in preventing dementia.
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