New research suggests that current vitamin B12 guidelines may not adequately protect the aging brain. A study found that older adults with “normal” but lower levels of active B12 showed signs of slower thinking and delayed visual processing. These individuals also exhibited more damage to the brain’s white matter, which facilitates communication between brain regions.
The University of California, San Francisco (UCSF) led this study. Researchers focused on the biologically active form of vitamin B12. This form may better indicate the amount of B12 the body can utilize. The findings suggest that the minimum threshold for defining B12 deficiency might not detect early functional changes in the nervous system.
The study, published in *Annals of Neurology*, included 231 healthy participants. Their average age was 71. None had dementia or mild cognitive impairment. Participants with lower active B12 levels had slower processing speeds on cognitive tests. This effect was more pronounced in older participants. They also showed delayed responses to visual stimuli, indicating slower visual processing and reduced brain signaling efficiency.
Magnetic Resonance Imaging (MRI) scans revealed additional concerns. Participants with lower active B12 had a higher volume of white matter lesions. These brain injuries are associated with cognitive decline, dementia, and stroke risk. Older adults may be more vulnerable to lower B12 levels due to less efficient absorption with age. Certain medications, digestive conditions, and diets low in animal products can also increase this risk.
These findings do not definitively prove that lower active B12 directly causes cognitive decline. They also do not suggest that all older adults should take supplements without medical advice. However, the study indicates that the current definition of B12 deficiency may be insufficient for optimal brain health. Clinicians may need to consider looking beyond total B12 levels, especially when older patients present with neurological symptoms.
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