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Low vitamin B12 is linked to brain shrinkage and thinking problems, a new study reports.

Low vitamin B12 linked to brain shrinkage and thinking problems in elderly, a new study reports.

The idiom “losing my marbles” is normally said in jest, but memory decline can be a truly frightening part of getting older. Fortunately, people can take heart in recent research showing that the right nutrients in the diet can help provide cognitive support. Now a new study reports that vitamin B12 may be crucial for preserving the brain.

Researchers at Rush University Medical Center in Chicago found that individuals with lower levels of vitamin B12 are more likely to have smaller brains as revealed by MRI scans and scored poorly on cognitive skills tests.

The results, published in the Sept. 27 issue of Neurology, came from a blood analysis of 121 subjects  who are a part of the Chicago Health and Aging Project (CHAP), a large, ongoing prospective study of 10,000 subjects over the age of 65.

“Our findings lend support for the contention that poor vitamin B12 status is a potential risk factor for brain atrophy [shrinking] and may contribute to cognitive impairment,” said Christine Tangney, Ph.D., a clinical nutritionist, who was the lead author of the study.

The brain relies on vitamin B12 because it is necessary for myelin synthesis, the  protective sheath around neurons. Vitamin B12 is also required for detoxifying homocysteine, an amino acid that can be toxic to the brain, and known to be elevated in vitamin B12 deficient people. In this study, increases in homocysteine were associated with decreased cognitive scores.

Normally, people are able to obtain sufficient amounts of vitamin B12 from their diets from animal products, especially liver, milk, eggs and poultry. As people get older, however, their stomachs lose the ability to secrete sufficient hydrochloric acid to release B12 from food.

Absorption may be further complicated by failure of cells of the stomach lining to secrete intrinsic factor, a protein necessary for bind to B12 enabling it to pass through the wall of the small intestine. The inability to absorb B12 can be difficult to detect eventually leading to deficiency and pernicious anemia, often requiring treatment with B12 injections.  

Other groups at risk for B12 deficiency are vegans and those with intestinal disorders.

Dietary supplementation could serve an important role for assisting older people achieve optimal intakes and absorption of B12. For example, a previous study from the United Kingdom showed high-dose supplementation may help to reduce the rate of brain decline and protect thinking and memory.

“It’s too early to say whether increasing vitamin B12 levels in older people through diet or supplements could prevent these problems, but it is an interesting question to explore,” Tangney said. “Findings from a British trial with B vitamin supplementation are also supportive of these outcomes.”

But could supplementation hurt? Studies on vitamin B12 have long established it as  completely safe having no association with any toxicity even when taken in extremely high amounts. And, given its potential of guarding the brain, it seems like the sensible thing to do. It’s nothing to lose your marbles over.

Reference: Tangney CC, Aggarwal NT, Li H, Wilson RS, Decarli C, Evans DA, Morris MC. Vitamin B12, cognition, and brain MRI measures: A cross-sectional examination. Neurology 2011;77(13)1276-1282. doi: 10.1212/WNL.0b013e3182315a33

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