People with higher blood levels of the vitamin were six times less likely to experience brain shrinkage compared with people with lower vitamin levels, according to results published in the new issue of the journal Neurology.
The study followed 107 community-dwelling volunteers aged between 61 and 87, and expands the science behind vitamin B12 levels and brain health. Previously, increased levels of vitamin B12 and other B vitamins were linked with lower levels of homocysteine, an amino acid reported to increase the risk of dementia or cognitive impairment.
"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," said lead author Anna Vogiatzoglou.
"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. Without carrying out a clinical trial, we acknowledge that it is still not known whether B12 supplementation would actually make a difference in elderly persons at risk for brain shrinkage."
Vitamin B12, also known as cobalamin, is only found in food of animal origin, including meat, milk and eggs. The recommended daily intake of vitamin B12 in Europe is 2.5 micrograms.
Vogiatzoglou and co-workers recruited the community-dwelling volunteers and collected blood samples to measure levels of vitamin B12, holotranscobalamin (holoTC), methylmalonic acid, total homocysteine, and folate. Brain volume loss per year was calculated using MRI scans.
Over five years of study, the researchers noted a greater decrease in brain volume among people with lower vitamin B12 and holoTC levels.
Indeed, people with lower levels of B12, defined as blood levels below 308 picomoles per litre, were six times more likely to experience brain shrinkage, said the researchers. On the other hand, high levels of methylmalonic acid or homocysteine, or low folate levels were not linked to brain volume loss.
“Low vitamin B12 status should be further investigated as a modifiable cause of brain atrophy and of likely subsequent cognitive impairment in the elderly,” stated the researchers.
It is important to note that none of the volunteers were vitamin B12 deficient.
"Previous research on the vitamin has had mixed results and few studies have been done specifically with brain scans in elderly populations. We tested for vitamin B12 levels in a unique, more accurate way by looking at two certain markers for it in the blood," said Vogiatzoglou.
The potential of supplements
Commenting independently on the results, Dr Susanne Sorensen from the Alzheimer's Society said: "Shrinkage is usually associated with the development of dementia.
"As vitamin B may be given as a food supplement, it may be useful to include tests of vitamin B levels in the general assessment of health of older individuals.
"This is another example of why it is crucial for people to lead a healthy lifestyle with a balanced diet rich in B vitamins and antioxidants.”
B for brain?
A University of Oxford study reported in 2007 that increased vitamin B12 levels may reduce the rate of age-related cognitive decline and dementia by 30 per cent.
The study, published in the American Journal of Clinical Nutrition, followed 1648 participants for 10 years and also found that increased levels of the amino acid homocysteine doubled the risk of dementia or cognitive impairment.
Previously, epidemiological studies have reported that high levels of the amino acid homocysteine are associated with suspected or confirmed dementia. Indeed, the Framingham study reported that people with homocysteine levels above 14 micromoles per litre of serum had twice the risk of dementia.
Source: Neurology 9 September 2008, Volume 71, Pages 826-832“Vitamin B12 status and rate of brain volume loss in community-dwelling elderly”Authors: A. Vogiatzoglou, H. Refsum, C. Johnston, S. M. Smith, K. M. Bradley, C. de Jager, M. M. Budge, A. D. Smith