Low vitamin B12 linked to changes in memory and stress markers

A study of 90 healthy adults aged 45 to 65 found different blood levels of several markers among those with low vitamin B12.

Editorial illustration — not from the study.

Researchers measured vitamin B12 and five blood markers in 90 healthy adults aged 45 to 65. The participants were divided into groups with sufficient, insufficient or deficient vitamin B12 levels, with 30 people in each group.

Compared with the sufficient group, people with insufficient or deficient vitamin B12 had higher levels of amyloid-beta 42, while the deficient group had lower levels of a nerve-supporting protein, acetylcholinesterase and the antioxidant glutathione. Calcium levels rose in the insufficient group but returned to similar levels in the deficient group.

Changes in blood markers

The study compared three groups: people with vitamin B12 levels above 300 pg/ml, those with levels from 201 to 300 pg/ml, and those with levels of 200 pg/ml or lower. Amyloid-beta 42, a protein studied in relation to brain health, was significantly higher in both the insufficient and deficient groups than in the sufficient group (p<0.001).

The deficient group had an apparent reduction in brain-derived neurotrophic factor, a protein involved in nerve support, and a significant decline in acetylcholinesterase compared with the sufficient group (p=0.029). Glutathione, an antioxidant that helps protect cells from oxidative stress, was also significantly lower in the deficient group (p<0.001). Blood calcium increased in the insufficient group and then returned toward the sufficient group's level in the deficient group.

Why the link matters

The findings suggest that vitamin B12 deficiency is associated with changes in blood markers related to memory, nerve function and oxidative stress, even among adults described as otherwise healthy. This supports the study's proposal that vitamin B12 deficiency could be a modifiable contributor to cognitive decline, but the results do not establish that treating the deficiency would prevent dementia.

Evidence and caveats

This was a cross-sectional study, meaning vitamin B12 levels and the blood markers were measured at one point in time. It included 90 participants, with 30 in each vitamin B12 group, so it cannot determine whether deficiency caused the marker changes or whether the changes predict later memory problems or dementia. The abstract reports biomarker measurements rather than results from cognitive tests, and it does not report follow-up after vitamin B12 treatment.

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