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New study suggests current recommendations for older adults may need revision
Meeting the minimum requirement for vitamin B12, essential for DNA synthesis, red blood cell production, and nerve tissue maintenance, may not be sufficient to prevent neurological decline, particularly in older adults. In fact, maintaining only the minimum levels may increase the risk of cognitive impairment, according to a new study led by researchers at the University of California, San Francisco (UCSF).
The study, published in the Annals of Neurology, found that older, healthy individuals with lower, yet still normal, concentrations of vitamin B12 displayed signs of neurological and cognitive deficiencies. Researchers observed that participants with lower B12 levels had greater damage to the brain’s white matter—the nerve fibers responsible for communication between different regions of the brain. These individuals also performed worse on tests measuring cognitive and visual processing speeds compared to those with higher levels of B12.
Call for Updated B12 Recommendations
The study was led by Dr. Ari J. Green of the UCSF Departments of Neurology and Ophthalmology and the Weill Institute for Neurosciences. He emphasized that existing guidelines for B12 sufficiency might overlook subtle yet functionally significant effects of the vitamin’s levels on cognitive health.
“Previous studies defining ‘healthy’ amounts of B12 may have missed subtle functional manifestations of high or low levels that affect people before any overt symptoms appear,” said Dr. Green. “Revisiting the definition of B12 deficiency to incorporate functional biomarkers could lead to earlier intervention and prevention of cognitive decline.”
Study Findings: Slower Processing Speeds and Brain Lesions
The UCSF study analyzed data from 231 healthy individuals aged 71 on average, all without dementia or mild cognitive impairment. The participants were recruited through UCSF’s Brain Aging Network for Cognitive Health (BrANCH) study. Their average blood B12 levels were 414.8 pmol/L—well above the U.S. minimum threshold of 148 pmol/L.
Researchers adjusted for factors such as age, sex, education, and cardiovascular risks, then focused on the biologically active form of B12—the component actually utilized by the body. Those with lower active B12 levels exhibited slower cognitive processing speeds and delays in responding to visual stimuli, suggesting slower brain conductivity. MRI scans also revealed an increased volume of lesions in the brain’s white matter, which is associated with cognitive decline, dementia, and stroke risk.
Co-first author Alexandra Beaudry-Richard, MSc, noted that older adults may be particularly vulnerable to lower levels of B12. However, she warned that these deficiencies could have a broader impact than previously recognized.
“These lower levels could impact cognition to a greater extent than we thought and may affect a much larger proportion of the population than we realize,” said Beaudry-Richard, who is completing her doctorate in research and medicine at UCSF and the University of Ottawa.
Implications for Clinical Practice
Given these findings, experts suggest that clinicians reconsider B12 supplementation in older patients experiencing neurological symptoms, even if their levels fall within the current normal range.
“In addition to redefining B12 deficiency, clinicians should consider supplementation in older patients with neurological symptoms,” Beaudry-Richard stated. “Ultimately, we need to invest in more research into the underlying biology of B12 insufficiency, since it may be a preventable cause of cognitive decline.”
Disclaimer
This article is for informational purposes only and does not constitute medical advice. Individuals concerned about their vitamin B12 levels or cognitive health should consult a qualified healthcare provider.
