Vitamin D deficiency 'increases dementia risk'
7 August 2014 Last updated at 10:32 BST
Older people who are Vitamin D deficient are at a substantially increased risk of developing dementia, a study in the journal Neurology has found.
Speaking on BBC Radio 4's Today programme, one of the authors of the study, Dr Iain Lang from the University of Exeter, said: "This is the first time this has been done on this scale and we're quite surprised that the results are so big."
And he added: "I don't think this is the key to dementia but it's a really important step in finding out what might be going on there."
First broadcast on BBC Radio 4's Today programme Thursday 7 August.