Having higher vitamin B12 levels may help protect against brain shrinkage in older adults according to new evidence published by Oxford researchers. Shrinking of the brain has been associated with cognitive impairment in the elderly. The findings reported in Neurology (September 8, 2025) suggest that by improving vitamin B12 status we may be able to protect the brain and thus possibly prevent cognitive decline in aging adults.
The study followed 107 healthy community-dwelling adults aged 61 to 87 for five years. Cognitive testing, brain MRI and CT scans to measure brain volume and blood sample collection to assess vitamin B12 levels were performed at baseline and once a year throughout the study. All study participants were free of dementia at baseline based on cognitive testing.
Even though all participants had vitamin B12 status within what is currently considered the normal range at baseline, the study found that plasma vitamin B12 and holoTC (holotranscolbamin) levels at follow-up were strong predictors of brain volume loss. Participants with vitamin B12 levels in the upper tertile were six times less likely to experience brain shrinkage than those with levels in the lower tertile (<308 pmol/L).
This study shows that low vitamin B12 status (within the normal range) is an important risk factor for loss of brain volume within healthy older adults. CBC news reported that according to study lead, Prof. David Smith, the brain normally shrinks about 0.5% per year in normal elderly brains, compared with 1% in people with mild cognitive impairment and 2% in those with Alzheimer�s disease. While more research is needed, these results suggest that plasma vitamin B12 status may be an early marker of brain atrophy and an important modifiable risk factor for cognitive decline in the elderly.
Cognitive impairment and dementia are common and represent a major public health concern in aging populations. Low vitamin B12 status is also common in the elderly. This study indicates that subclinical low vitamin B12 status, even within the normal range, may lead to brain volume loss which in turn is associated with cognitive decline. Study lead, Prof. David Smith suggested that it might be prudent to aim to keep vitamin B12 levels higher in the normal range according to an article published in the Globe and Mail. He indicated that this can be achieved by eating plenty of foods that are good sources of vitamin B12 such as meat, fish, milk, other dairy products and fortified breakfast cereals.
Read the study abstract, Vitamin B12 status and rate of brain volume loss in community-dwelling elderly, by Vogiatzoglou A et at. in Neurology, 2008; 71:826-832.
See the BIC Nutrition Perspective on Vitamin B12 and the Health of Canadians (September 2006) and the accompanying simple 2 page fact sheet for your practice.
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