Epoch HealthNormal Vitamin B12 Levels May Still Be Too Low for Brain Health, Study Finds

Recent research from UCSF challenges current B12 reference ranges, suggesting that levels considered “normal” (118-701 pmol/L) may still be insufficient for optimal brain health in older adults. The study examined cognitive processing speed and white matter integrity in 231 healthy older adults (mean age 71) without dementia or MCI.

Key Clinical Considerations

• Study participants had mean B12 levels of 414.8 pmol/L (above US minimum threshold of 148 pmol/L), yet those with lower-normal levels showed measurable white matter damage on MRI.
• Lower-normal B12 levels were associated with slower processing speeds and reduced brain conductivity, with effects more pronounced in older participants.
• Age-related decline in stomach acid production impairs B12 absorption, potentially necessitating higher intake or supplementation despite “normal” serum levels.
• Visual processing tests using electrodes to measure brain response demonstrated measurable neurological deficits in those with lower-normal B12 levels.
• Researchers advocate for redefining B12 deficiency to incorporate functional biomarkers rather than relying solely on current reference ranges.

Clinical Practice Impact

• Patient Assessment: Consider B12 testing in older patients with subtle cognitive complaints even without overt deficiency symptoms; visual processing assessments may detect early changes.
• Supplement Recommendations: Clinicians should consider B12 supplementation for older patients with neurological symptoms even when levels fall within current reference ranges.
• Dietary Counseling: Emphasize consumption of B12-rich animal products (meat, fish, dairy, eggs) and discuss fortified alternatives for vegetarian/vegan patients.
• Risk Stratification: Patients with multiple risk factors for B12 malabsorption (advanced age, PPI use, metformin, gastric surgery) may benefit from prophylactic supplementation despite “normal” levels.
• Future Monitoring: Follow emerging research on updated B12 reference ranges and consider implementing revised thresholds as evidence accumulates.

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