People lacking a particular type of vitamin D may be at an increased risk of developing Alzheimer's disease, a new study suggests.

Vitamin D has a key role in the development and maintenance of strong teeth and bones and is thought to help protect the body against a number of serious conditions, including some neurological diseases and cancer. This latest study relates to vitamin D2. While most people associate vitamin D with sun exposure, vitamin D2 is actually obtained from foods, such as fish, eggs and fortified milk.

UK scientists spent six months analysing the blood samples of patients with Alzheimer's. These included people who were on medication for the condition and people who were not. All were compared with a group who did not have Alzheimer's.

The study found that those with the condition who were not on any medication had very low levels of vitamin D2.

"The vitamin was either non-existent or in such low quantities that it could barely be measured. In comparison, people in the study who were either being treated with drugs to control their Alzheimer's, or who didn't have the condition at all, showed far higher levels," the scientists explained.

They noted that while there has been speculation for some time that vitamin D could be linked to Alzheimer's, this is thought to be the first time a specific connection with vitamin D2 has been found.

Meanwhile, the team also found that drugs used in the early stages of Alzheimer's treatment, known as Acetylcholinesterase inhibitors, may help 'switch on' the body's absorption of vitamin D2.

"Further investigations are now needed to determine whether simple dietary advice or giving a specific supplement could restore beneficial levels (of vitamin D2) in Alzheimer's patients," the scientists commented.

Details of these findings are published in the journal, Current Alzheimer Research.

Alzheimer's disease affects around 35,000 people in Ireland. For more on this condition, see our Alzheimer's Disease Clinic here