In a study published in the September 9, 2008, issue of the journal Neurology®, researchers from Oxford University and the University of Oslo report an association between decreased levels of vitamin B12 and a decline in brain volume. Reduced brain volume, or brain atrophy, has been associated with Alzheimer’s disease, and is used as a marker of the disease’s progression.
The study included 107 participants in the Oxford Project to Investigate Memory and Aging (OPTIMA), who did not have cognitive impairment upon enrollment. Magnetic resonance imaging (MRI) scans of the brain, cognitive assessments, and physical examinations were conducted at the beginning of the study and annually over a five year period. Blood plasma samples collected upon enrollment and yearly thereafter were analyzed for folate, B12, homocysteine, and the vitamin B12 markers holotranscobalamin, transcobalamin saturation and methylmalonic acid.
Comparison of MRI images obtained at the beginning of the study with those scanned after five years found a greater amount of brain volume loss among participants with low plasma levels of vitamin B12. Subjects whose plasma B12 levels were among the lowest one-third of participants at less than 308 picomoles per liter had a six times greater adjusted risk of increased brain volume loss than those whose vitamin B12 levels were in the top two-thirds. Similar patterns were observed for holotranscobalamin and transcobalamin saturation.
Although the initially observed association between increased homocysteine and brain atrophy disappeared in the adjusted analysis, the authors note that high homocysteine levels have been suggested as a risk factor for the condition. Elevated homocysteine has been associated with cognitive decline and dementia onset in a number of studies, and is related to insufficient levels of vitamin B12 and folate. Another proposed explanation for the current study’s findings are the lesions that have been observed in the brains of individuals with vitamin B12 deficiency, however, none of the participants in the current study were classified as deficient.
"Previous research on the vitamin has had mixed results and few studies have been done specifically with brain scans in elderly populations,” noted lead author Anna Vogiatzoglou, MSc, of the University of Oxford’s Department of Physiology, Anatomy and Genetics. “We tested for vitamin B12 levels in a unique, more accurate way by looking at two certain markers for it in the blood."
"Many factors that affect brain health are thought to be out of our control, but this study suggests that simply adjusting our diets to consume more vitamin B12 through eating meat, fish, fortified cereals or milk may be something we can easily adjust to prevent brain shrinkage and so perhaps save our memory," she advised. "Research shows that vitamin B12 deficiency is a public health problem, especially among the elderly, so more vitamin B12 intake could help reverse this problem."