The vitamin is thought to protect individuals against Alzheimer’s by reducing levels of an amino acid (homocysteine) in the blood that has been linked to the disease.
Individuals will all have varying levels of B12 in the blood but it is groups such as the elderly and vegetarians, both of whom are known to have low levels, that stand an increased risk.
Researchers from the Karolinska Institute in Stockholm, Sweden, whose findings were published in the journal Neurology, conducted a seven year long study in which they took blood samples from 271 Finnish people aged between 65 to 79 who did not have Alzheimer’s or any other form of dementia when the study began.
The blood samples taken were tested for levels of homocysteine, B12 and the active portion of the vitamin, known as holotranscobalamin.
Each small increase in the homocysteine concentration raised the risk of Alzheimer’s by 16%, however the risk was reduced by 2% every time levels of the active form of vitamin B12 went up.
Author of the study Dr Babak Hooshmand said”Our findings show the need for further research on the role of vitamin B12 as a marker for identifying people who are at increased risk of Alzheimer’s disease,” .