New research suggests current B12 recommendations may be insufficient for brain health
A recent study suggests that what is currently considered a “normal” level of vitamin B12 may not be enough to prevent dementia.
Researchers from the University of California, San Francisco (UCSF), examined 231 healthy older adults, with an average age of 71, who had no signs of dementia or mild cognitive impairment.
Their blood tests showed an average B12 level of 414.8 pmol/L, significantly higher than the U.S. recommended minimum of 148 pmol/L. However, those with lower B12 levels performed worse on cognitive and visual processing tests, indicating “subtle cognitive decline,” according to a UCSF press release.
The study also found that participants with lower B12 levels had more lesions in the brain’s white matter, a potential warning sign of cognitive decline, dementia, or stroke. These effects became more pronounced with age.
The findings, published on February 10 in the Annals of Neurology, have prompted researchers to call for an update to the current B12 requirements.
Should the definition of B12 deficiency change?
Dr. Ari J. Green, a senior author of the study from UCSF’s Departments of Neurology and Ophthalmology and the Weill Institute for Neurosciences, emphasized the need to redefine what is considered a healthy B12 level.
“Previous studies may have overlooked subtle functional effects of high or low B12 levels that impact people without causing obvious symptoms,” Green said. “Revisiting the definition of B12 deficiency to include functional biomarkers could lead to earlier intervention and prevention of cognitive decline.”
While the study focused on older adults—who may be particularly vulnerable to low B12 levels—researchers warned that the issue could affect a much larger proportion of the population than previously believed.
Co-first author Alexandra Beaudry-Richard, a doctoral researcher at UCSF and the University of Ottawa, suggested that doctors should consider B12 supplementation for older patients with neurological symptoms, even if their levels fall within the “normal” range.
“Ultimately, we need more research into the biology of B12 insufficiency, as it may be a preventable cause of cognitive decline,” she added.
Experts weigh in on B12’s role in brain health
Dr. Brett Osborn, a Florida neurosurgeon and longevity expert, stated that the study supports the idea that current B12 guidelines are inadequate for optimal brain health.
“Even participants with B12 levels considered ‘normal’ by today’s standards showed clear signs of neurological impairment—slower processing speeds, increased white matter abnormalities on MRI, and elevated tau protein, a marker of neurodegeneration,” Osborn told Fox News Digital.
Osborn criticized current medical guidelines, arguing that minimum recommendations were set based on population averages, not on what is best for cognitive function and longevity.
“In my clinic, we recommend B-complex supplements, including B12, to help regulate homocysteine levels—an amino acid linked to brain function. When homocysteine is elevated, which can indicate low B12, cognitive function declines,” he explained.
However, he acknowledged that the study was observational and that correlation does not prove causation. Still, he questioned whether further trials were necessary:
“Do we really need a randomized controlled trial to confirm that optimizing B12 intake benefits brain health? That’s like waiting for a study to confirm that eating vegetables is good for you. The science is crystal clear.”
Osborn called for an update to the standard B12 lab levels, arguing that health should be defined by optimal ranges rather than what is considered “normal” in an increasingly unhealthy population.
Is more B12 always better?
Dr. Earnest Lee Murray, a board-certified neurologist at Jackson-Madison County General Hospital in Tennessee, agreed that the study raises important questions about redefining B12 deficiency.
“Past research has recommended B12 supplementation for those with a diagnosed deficiency to prevent cognitive decline. However, there is no clear evidence that B12 supplementation benefits individuals without a deficiency,” Murray, who was not involved in the study, told Fox News Digital.
He also cautioned against taking excessive doses of vitamins, including B12.
“In most cases, high levels of B12 won’t cause harm, but excessive intake can sometimes lead to issues,” he warned.
Murray recommended that older adults or those at risk of cognitive decline consult their doctors about testing—not just for B12 levels but for other markers that could indicate improper absorption of the vitamin.
As research continues, experts agree that maintaining adequate B12 levels may play a key role in supporting brain health and reducing the risk of cognitive decline.
