An insufficient vitamin D supply may increase dementia risk

A new US study reports that older people with vitamin D deficiency seem to have a substantially increased risk of developing dementia and Alzheimer’s disease.

The observational study measured blood vitamin D concentrations of 1,658 mental and cardiovascular healthy adults aged 65 and over and documented cases of dementia such as Alzheimer’s disease during six years (1). The study results showed that participants who were moderately deficient in vitamin D (25 to 50 nmol/L) had a 53% increased risk of developing dementia of any kind, and the risk increased to 125% in those who were severely deficient (below 25 nmol/L). Similar results were recorded for Alzheimer’s disease, with the moderately deficient group 69% more likely to develop this type of dementia, increasing to a 122% elevated risk for those severely deficient. Vitamin D blood levels above 50 nmol/L were most strongly associated with good brain health.

The researchers commented that 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. The new results do not demonstrate that low vitamin D levels cause dementia. It has been estimated that 44 million people worldwide suffer from dementia – a number expected to triple by 2050 as a result of rapid population aging. A billion people worldwide are thought to have low vitamin D levels and many older adults may experience poorer health as a result.

1. Littlejohns T. J. et al. Vitamin D and the risk of dementia and Alzheimer disease. Neurology. Published online August 2014.