Scientists have discovered a major flaw in vitamin B12 guidelines,

which could put your brain at risk.

New research suggests that today’s B12 guidelines might be outdated, as even “normal” levels could still harm brain function. Scientists warn that subtle cognitive decline linked to B12 insufficiency might affect more people than expected. The source is SciTechDaily.com.

Even if your levels are considered to be "normal," it's possible that your brain isn't getting enough B12. 

A new study suggests that even within the accepted range, older adults with lower B12 levels exhibit signs of brain damage and cognitive decline. 

White matter lesions linked to dementia were also found in these individuals, as were slower thinking and reaction times, according to the researchers. 

Still Linked to Brain Deficiency by Normal B12 Levels Getting the recommended amount of vitamin B12 is essential for making DNA, red blood cells, and nerve tissue.

However, new research suggests that, particularly for older adults, meeting the minimum requirement may not be sufficient. 

Even if B12 levels are within the normal range, having lower levels may actually raise the risk of cognitive impairment. 

Healthy older adults with lower B12 levels showed signs of neurological and cognitive decline, according to a University of California, San Francisco-led study.

These individuals had more damage to the brain’s white matter the nerve fibers that enable different parts of the brain to communicate and performed worse on tests measuring cognitive and visual processing speeds compared to those with higher B12 levels.

The study was published in Annals of Neurology on February 10.

Rethinking B12 Guidelines for Brain Health

Dr., senior author of the study, Ari J. Green, from UCSF’s Departments of Neurology and Ophthalmology and the Weill Institute for Neurosciences, says the findings raise concerns about current B12 recommendations.

“Previous studies that defined healthy amounts of B12 may have missed subtle functional manifestations of high or low levels that can affect people without causing overt symptoms,” said Green, noting that clear deficiencies of the vitamin are commonly associated with a type of anemia.

 Incorporating functional biomarkers into the definition of B12 deficiency "could lead to earlier intervention and prevention of cognitive decline." 

Lower B12 Correlates with Slower Processing Speeds, Brain Lesions

In the study, researchers enrolled 231 healthy participants without dementia or mild cognitive impairment, whose average age was 71. They were recruited by the UCSF study known as the Brain Aging Network for Cognitive Health (BrANCH). Their blood B12 levels were on average 414.8 pmol/L, well above the 148 pmol/L requirement in the United States. 

Adjusted for factors like age, sex, education, and cardiovascular risks, researchers looked at the biologically active component of B12, which provides a more accurate measure of the amount of the vitamin that the body can utilize. In cognitive testing, participants with lower active B12 were found to have slower processing speed, relating to subtle cognitive decline. The effects were exacerbated by getting older. 

They also showed significant delays responding to visual stimuli, indicating slower visual processing speeds and generally slower brain conductivity.

Cognitive Decline Could Affect More People Than Expected

Lesions in the participants' white matter were found to be more numerous on MRIs, which may be related to stroke, dementia, or cognitive decline. Co-first author Alexandra Beaudry-Richard, MSc, stated that these lower levels could "impact cognition to a greater extent than what we previously thought, and may affect a much larger proportion of the population than we realize," even though the study volunteers were older adults who may be particularly susceptible to lower levels of B12. Beaudry-Richard is currently working on her doctoral dissertation in the UCSF Department of Neurology and the University of Ottawa's Department of Microbiology and Immunology.

 Rethinking B12 Supplementation and Deficiency “In addition to redefining B12 deficiency, clinicians should consider supplementation in older patients with neurological symptoms even if their levels are within normal limits,” she said.

 “Ultimately, we need to invest in more research about the underlying biology of B12 insufficiency, since it may be a preventable cause of cognitive decline.”

Reference: “Vitamin B12 Levels Association with Functional and Structural Biomarkers of Central Nervous System Injury in Older Adults” by Alexandra Beaudry-Richard, Ahmed Abdelhak, Rowan Saloner, Simone Sacco, Shivany C.

 Frederike C. Montes Christian Cordano, Christian Oertel, Nour Jabassini, Kirtana Ananth, Apraham Gomez, Azeen Keihani, Makenna Chapman, Sree Javvadi, Shikha Saha, Adam Staffaroni, Christopher Songster, Martin Warren, and John W. Boscardin, Bruce Miller, Joshua W., and Joel Kramer Ralph Green, Miller, and Ari J. Green, 10 February 2025,Annals of Neurology.








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