Low vitamin B12 levels may lead to brain shrinkage, cognitive
problems Older people with low levels of vitamin B12 in their
blood may be more likely to lose brain cells and develop
problems with their thinking skills, according to a study
published in the September 27, 2011, print issue of Neurology,
the medical journal of the American Academy of Neurology. Foods
that come from animals, including fish, meat, especially liver,
milk, eggs and poultry, are usually sources of vitamin B12. The
study involved 121 people age 65 and older living on the south
side of Chicago. Their blood was drawn to measure levels of
vitamin B12 and B12-related metabolites that can indicate a B12
deficiency. The participants also took tests measuring their
memory and other cognitive skills. An average of four-and-a-half
years later, MRI scans of the participants' brains were taken to
measure total brain volume and look for other signs of brain
damage. Having high levels of four of five markers for vitamin
B12 deficiency was associate