The study was carried out by researchers from the University of Exeter Medical School in the UK, Angers University Hospital in France, and Florida International University, Columbia University, the University of Washington, the University of Pittsburgh, the Veteran Affairs Ann Arbor Center for Clinical Management Research, and the University of Michigan in the US.
People lacking in vitamin D have a higher risk of developing dementia report several media outlets, including BBC News and The Independent. People lacking in vitamin D have a higher risk of developing dementia report several media outlets, including BBC News and The Independent.
A study found people severely lacking in the sunshine vitamin were twice as likely to develop dementia and Alzheimer's disease compared with people with healthy levels (50nmol/l or more).
The findings are based on a study of more than 1,650 people aged 65 and above who were followed over a period of about six years to see if they developed dementia.
Researchers found the higher the vitamin D deficiency, the higher the risk of developing dementia and Alzheimer's disease.
They found severe vitamin D deficiency (less than 25nmol/l) is associated with approximately twice the risk of developing dementia or Alzheimer's disease.
Moderately low levels of vitamin D (between 25nmol/l and 50nmol/l) are associated with a 50% increase in risk.
This study was able to show an association between low levels of vitamin D and the risk of developing dementia. But it does not prove that vitamin D deficiency causes the disease.
Other factors that can increase the risk of developing dementia, including a poor diet, lack of activity and general poor health, can also cause a low vitamin D level.
More research is needed to establish whether eating vitamin D-rich foods, such as oily fish, or taking vitamin D supplements could delay or even prevent dementia.