Vitamin B12 Linked to Brain Shrinkage

Vitamin B12 is an essential water-soluble vitamin which helps maintain healthy nerve cells, red blood cells and is also needed to help make DNA, the genetic material in all cells. This vitamin is naturally found in foods that come from animals, including fish, meat, poultry, eggs, milk and milk products. While two national studies found that most Americans consume recommended amounts of B12, others suggest that two out of five people are deficient in the vitamin. Early and fairly pronounced deficiency does not always cause distinct or specific symptoms, but even low levels of vitamin B12 may be contributing to brain atrophy.

Researchers from the University of Oxford in England studied 107 volunteers between 61 and 87, all of whom were cognitively normal at the beginning of the study. They were divided into three groups, depending on their vitamin B12 levels. None of the participants were deficient in vitamin B12 and even the group with the lowest levels was still above a threshold used by some scientists to define vitamin B12 deficiency. All were given annual clinical exams, MRI scans, cognitive tests and had blood samples taken.

At the end of a five year period, the individuals with lower vitamin B12 levels at the beginning of the study had a greater decrease in brain volume. However, those with the lowest levels of B12 were more than six times as likely to experience brain shrinkage, compared to those with the highest B12 levels. “This study adds another dimension to our understanding of the effects of B vitamins on the brain—the rate of shrinkage of the brain as we age may be partly influenced by what we eat,” said Professor David Smith, who directs the Oxford Project to Investigate Memory and Aging.

Study co-author Anna Vogiatzoglou, a registered dietician and doctoral candidate in the department of physiology, anatomy and genetics at the University, said that even though the study doesn’t confirm that lower B12 levels cause brain atrophy, which has been associated with impaired cognitive function and Alzheimer’s disease, it does suggest that “we ought to be more aware of our B12 status, especially people who are vulnerable to B12 deficiency (elderly, vegetarians, pregnant and lactating women, infants, and those who cannot use or absorb B12), and take steps to maintain it by eating a balanced and varied diet.”

The next step is to identify the biological mechanisms behind the link and determine if added B12 could avert brain atrophy. “We are doing a clinical trial in Oxford in which we are giving B vitamins (including B12) to elderly people with memory impairment,” said Vogiatzoglou. “In this trial, we are doing MRI scans at the start and at the end, and so we will be able to find out if taking B vitamins really does slow down the shrinking of the brain. The trial will be completed in 2009.”

Experts say this study adds one more advantage to leading a healthy lifestyle and eating a balanced diet rich in B vitamins and antioxidants. Getting your RDA of vitamin B12 can be as easy as eating one chicken breast + one hard-boiled egg + one cup of plain low-fat yogurt, or one cup of milk + one cup raisin bran. For more information about building a healthful diet, refer to the Dietary Guidelines for Americans  and the U.S. Department of Agriculture’s MyPyramid food guidance system.