Low Vitamin B12 Levels Linked to a Shrinking Brain

October 14, 2008

October 14, 2008

Low levels of vitamin B12 in elderly people may cause the brain to shrink. The findings, though preliminary, suggest that healthy levels of the B vitamin may be critical for robust brain functioning. A shrinking brain has also been linked to Alzheimer’s and impaired thinking and memory. The findings appeared in Neurology, the medical journal of the American Academy of Neurology.

In the study, researchers from Britain followed 107 men and women, ages 61 to 87, for five years. All were mentally sharp and free of dementia at the start of the study. The scientists used M.R.I. brain scans to measure how big the brain was, and blood tests to measure levels of vitamin B12.

Study participants were divided into three groups, based on their B12 levels. The group with the lowest levels of vitamin B12 at the start of the study lost twice as much brain volume as those with the highest levels. The difference was significant, even after researchers considered such factors as initial brain size, age, sex, education and cognitive test scores.

“Many factors that affect brain health are thought to be out of our control, but this study suggests that simply adjusting our diets to consume more vitamin B12 through eating meat, fish, fortified cereals or milk may be something we can easily adjust to prevent brain shrinkage and so perhaps save our memory,” said study author Anna Vogiatzoglou of Oxford University.

Research shows that vitamin B12 deficiency is common among seniors, who are less able to absorb the nutrient effectively through their gut. “More vitamin B12 intake could help reverse this problem,” said Vogiatzoglou.

However, the study did not look at whether taking vitamin B12 supplements would have similar benefits for the brain. David Smith, another author of the study, said the work established an association between low B12 levels and a shrinking brain, but it’s not clear if the nutrient deficiency actually caused the shrinkage.

“This doesn’t mean you should go out and buy vitamin B12 tablets tomorrow,” he said. “We need to know the results of a clinical trial in which we’re testing whether B12 does actually prevent brain shrinkage.”

Vitamin B12, also known as cyanocobalamin, is essential for healthy function of blood and nerve cells. Foods rich in the vitamin include meats like beef, lamb, liver and fish, clams and oysters, and milk and eggs.

It is recommended that adults get at least 2.4 micrograms of vitamin B12 daily, with higher amounts needed for pregnant women. Because deficiencies of the vitamin are so common in the elderly, experts advise that seniors, or those who care for them, ask their doctors to check their B12 levels.

Other studies have shown that other B vitamins, like folic acid, may also have benefits for the brain. However, it is still too early to say whether adults should routinely be taking higher doses of B12, folic acid or other B vitamins as a preventive measure against memory loss or Alzheimer’s.

More research is needed to determine the link between B vitamins and Alzheimer’s disease. Your best bet may be to follow a heart-healthy diet rich in fruits and vegetables and whole grains to help maintain the brain and preserve the memory. A sound diet helps to maintain the health of the blood vessels, including those that supply oxygen and nutrients to the brain. In addition, regular exercise and mental and social stimulation is thought to be critical to keeping the mind active and alert into old age.

By www.ALZinfo.org, the Alzheimer’s Information Site. Reviewed by William J. Netzer, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University


A. Vogiatzoglou, MSc, H. Refsum, MD, PhD, C. Johnston, S. M. Smith, DPhil, K. M. Bradley, FRCR, FRCP, C. de Jager, PhD, M. M. Budge, MD and A. D. Smith, DPhil, FMedSci: “Vitamin B12 status and rate of brain volume loss in community-dwelling elderly.” Neurology, Volume 71, September 9, 2008, pages 826-832.


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