Vitamin B12 may protect against Alzheimer's disease, a small new study in Neurology suggests.
Researchers already know that high levels of vitamin B12 in the blood can help reduce levels of an amino acid called homocysteine in the blood. Some studies have linked homocysteine to an increased risk of Alzheimer's disease, memory loss, and stroke, but it isn't clear if high homocysteine levels are just a sign of disease or have a role in the disease.
For this study, researchers took blood samples from 271 Finnish people, aged 65 to 79, who did not have dementia at the start of the study.
During the seven-year study, 17 people, or six per cent of the group, developed Alzheimer's disease. Blood samples were tested for levels for homocysteine and for levels of the active portion of the vitamin, called holotranscobalamin.
The study found that for each increase in the concentration of homocysteine, the risk of Alzheimer's disease increased by 16 per cent, whereas each picomolar increase in concentration of the active form of vitamin B12 reduced the risk by two per cent.
The results stayed the same after taking into account other factors, such as age, gender, education, smoking status, blood pressure and body mass index. The addition of folate did not appear to raise or lower the risk of Alzheimer's disease.
"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," said study author Dr. Babak Hooshmand, with Karolinska Institutet in Stockholm, Sweden.
Hooshmand noted that low levels of vitamin B12 are surprisingly common in the elderly. It's commonly found in eggs, fish, poultry and other meats, though it also appears in multivitamins.
Yet few studies have investigated the usefulness of vitamin B12 supplements to reduce the risk of memory loss.
Nevertheless, the study authors caution against taking vitamin B12 supplements until more research is done
Hooshmand says his study was small and says more research is needed to confirm the findings "before vitamin B12 should be used solely as a supplement to help protect memory," he said.
