Earlier studies have indicated that sub-optimal poor vitamin B12 status may be a risk factor for brain atrophy and possibly cognitive impairment.

Chicago researchers at Rush University Medical Center have found that low levels of vitamin B12 may contribute to brain function decline (thinking in particular) for senior adults in many ways.

According to Christine C. Tangney, PhD, of Rush University Medical Center in Chicago, she and her colleagues found that several indicators of vitamin B12 insufficiency all predicted lower global cognitive scores over nearly five years of follow-up,

The most significant factors were damage to the white matter lesions and cerebral infarcts (loss of blood flow) in association with the nonspecific marker homocysteine and brain shrinkage for the vitamin B12-specific marker methylmalonic acid (MMA).

“Vitamin B12 status may affect the brain through multiple mechanisms,” the group wrote in the Sept. 27 issue of Neurology.

This study, concentrations of vitamin B12–related markers (methylmalonate, cystathionine, homocysteine) are associated with global cognitive function and with total brain volume.

The Institute of Medicine already recommends B12 supplements for seniors, co-author Martha Clare Morris, ScD, director of nutrition at Rush University Medical Center, noted in an interview with MedPage Today.

“Insufficient vitamin B12 is very common in older people,” she explained. “The older we get we have a decreased ability to absorb vitamin B12 from our diet. … Medications can also impair absorption.”

But middle age adults may be another important population for screening and possible supplementation, Morris suggested.

Although her group’s observational study couldn’t say whether boosting B12 would prevent or reverse cognitive effects, a prior randomized trial demonstrated that high-dose B complex supplements could slow down brain atrophy in older adults.

The study, dubbed VITACOG, found that supplements prevented cognitive declines much better than placebo among those with high homocysteine levels.

“So at least from this one clinical trial it appears that [supplementation] may have some benefit,” Morris argued.

Her group made more detailed analyses into their data obtained in the Chicago Health and Aging Project (CHAP), measuring vitamin B12-related markers in relation to brain MRI and neuropsychological test results 4.6 years later in 121 Chicago residents, ages 65 and older.

After adjustment for age, sex, education, race, and blood creatinine levels to control for kidney function problems that could have an impact on homocysteine, all of the B12-related markers affected cognitive scores.

Although clinical screening typically relies on serum B12, Morris warned that this may not give a full picture of whether the effects of insufficiency are accumulating.

“You might be in the normal range, say in the low normal range, of vitamin B12 in your blood but still have evidence of insufficient vitamin B12 based on these biomarkers,” she toldMedPage Today.

The researchers cautioned that lack of more than one MRI and measurements prevented any conclusions on whether poor vitamin B12 status speeds up brain atrophy and demyelination.

Another limitation was the lack of data on serum folate and vitamin B6, they added.


Tangney CC, et al “Vitamin B12, cognition, and brain MRI measures: A cross-sectional examination” Neurology 2011; 77: 1276–1282.