The CNN “The Chart” blog reports  that “a deficiency in vitamin B12 is associated with memory and thinking problems, as well as brain shrinkage,” according to a study published in the journal Neurology.
The Time “Healthland” blog reports that researchers “followed a group of 121 people aged 65 or older for 4.5 years.”
The investigators “measured the participants’ blood levels of vitamin B12 and markers of its breakdown products.” The researchers “also recorded people’s performance on tests of thinking skills and took MRI scans of their brains.”
CNN says, “The study did not find an association between the serum B12 levels of participants and the likelihood of brain problems. Morris said that makes sense because while low levels negatively affect the brain, high levels above normal aren’t necessarily better than adequate levels.”
“There’s a level we should all have, and if you fall below that, it could cause problems,” she said.
Quantifying that level is up for debate, but the National Institutes of Health offers guidelines for recommended vitamin B12 intake at various ages.
Morris and colleagues did not look at this phenomenon in Alzheimer’s patients, but a small 2010 study in Neurology found that people who tended to eat vitamin B12-rich foods are less likely to develop Alzheimer’s than those who did not.
Vitamin B12 deficiency has not been shown to be directly involved in the pathology of Alzheimer’s in the brain, but it may aggravate the brain in other ways that could lead to Alzheimer’s. “We can’t discount its involvement,” Lah said.