Don’t forget your B12

As far as vitamins go, the popular belief has been that B – or B12, specifically – is for brain. Memory, cognition and brain size have all appeared to benefit from the dietary supplement.

A new study suggests, however, that vitamin B12 doesn’t slow cognitive decline in patients already diagnosed with mild to moderate Alzheimer’s disease. Symptoms did not improve in 202 patients put on high doses of the vitamin.

But don’t throw away your bottle of B vitamins just yet.

While the new study raises questions about the vitamin’s ability to treat Alzheimer’s disease, there is still a growing body of evidence indicating that it may be useful in preventing it. A number of clinical trials have determined that sufficient levels of vitamin B12 may be needed to keep the brain from shrinking and mental cognition from declining. So, it is more important than ever to make sure you’re getting enough of this nutrient.

Found in meat, fish and dairy products, vitamin B12 helps maintain healthy nerve cells and red blood cells. A new study by British and Australian researchers has found that it may in fact be essential for maintaining brain volume. Seniors who had the lowest – but not deficient – vitamin B12 levels were more likely to have brain shrinkage detected by MRI. Brain atrophy has been linked to impaired cognition and Alzheimer’s disease.

“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 in a press release.

The scientists said additional research is needed to prove that lower levels of B12 actually cause brains to shrink or memories to fade.  But the findings should be enough to encourage health-conscious individuals to have their vitamin B12 levels measured, they said.  Especially at risk are seniors, vegetarians, pregnant and lactating women and infants.

Despite the fact that vitamin B12 is in many common foods, federal research has determined that many more Americans are deficient than was once thought. Fully two in five Massachusetts residents had low values in a 2000 study.

“I think there is a lot of undetected vitamin B12 deficiency out there,” said study leader Katherine Tucker, a nutritional epidemiologist at the Jean Mayer USDA Human Nutrition Research Center on Aging.

Telltale signs of vitamin B12 deficiency include anemia, fatigue, constipation, loss of appetite and weight loss. Deficiencies have also been linked to numbness and tingling in the hands and feet, difficulty maintaining balance, depression and soreness of the mouth.

In the United States, vitamin B12 blood levels below 200 picograms per milliliter are considered abnormal. But in Japan and some European countries, which have long recognized the benefits of vitamin B12, the standards are much more rigorous. There, blood levels that fall below 500 picograms are considered deficient.

The recommended dietary allowance of vitamin B12 in the United States is 2.4 micrograms per day, the amount in a small serving of beef, salmon or trout. Because many older adults do not absorb vitamin B12 efficiently, people over 50 years of age should ask their doctor about taking a vitamin B12 supplement. The Institute of Medicine, which established the dietary guidelines for B12, considers the supplements safe, even at high levels. The agency noted “no adverse effects have been associated with excess vitamin B12 intake from food and supplements in healthy individuals.”

There have been some calls to raise the recommended dietary allowance. One 2006 study of postmenopausal Danish women determined that 6 micrograms per day might be more suitable than the 2.4 micrograms currently recommended for American adults.

This is one B vitamin that deserves an “A,” and not just for its benefits for cognition. As a physician, I have seen first-hand the importance of B12.  One memorable case was a man who had leg pain and difficulty walking and was considering undergoing back surgery.  I diagnosed his vitamin B12 deficiency and determined it was causing his symptoms.  After a few vitamin B12 injections, his pain went away. He no longer needed to walk with a cane, and surgery was avoided. Cost of treatment, about $30. Benefit, priceless.