April 4, 2011
New research points to a possible role for vitamin B12, a nutrient important for nerve and brain health, in the prevention of Alzheimer’s. People who had evidence of high levels of the vitamin in their blood appeared to be at lower risk of the disease.
But it’s too early to start gobbling vitamin supplements to ward off memory loss. Numerous studies have looked at the role of vitamins in brain health and found inconclusive results. Two rigorous studies earlier this year found that nutrients like B12 and folic acid, another B vitamin, did not protect against the disease.
Vitamin B12 is common in foods like eggs, meat, cheese, liver and fish. It is also found in brewer’s yeast, and some breakfast cereals are fortified with the vitamin as well. Vegetarians may need to watch their vitamin B12 levels to make sure they are getting enough. And many seniors are deficient in the vitamin, even if they eat animal products, because their bodies do not absorb it well. As a result, deficiencies may build up over years.
In the current study, published in Neurology, researchers from the Karolinka Institutet in Stockholm took blood samples from 271 Finnish men and women in their mid- to late-60s and 70s. None had Alzheimer’s or other serious memory problems at the study’s start.
By the end of the study period, seven years later, 17 people had been diagnosed with Alzheimer’s disease. Researchers measured blood levels of homocysteine, an amino acid that has been linked to heart disease, strokes and inflammation. The higher the levels of vitamin B12 somebody has, the lower the levels of homocysteine.
The researchers also looked at another related substance called holotranscobalamin, a protein found in the blood that transports vitamin B12 to cells and is necessary for B12 to be active. The chemical is sometimes also called “active B12” because it correlates with active levels of vitamin B12 in the blood.
The researchers found that as levels of homocysteine increased, the risk of Alzheimer’s disease increased modestly. But as levels of active B12 increased, the risk of Alzheimer’s decreased slightly. The results were independent of other Alzheimer’s risk factors like advancing age, low levels of education, smoking, high blood pressure and obesity. This could mean that prevention of B12 deficiency (which is common in the elderly) might reduce the risk of AD.
In this study, higher levels of folic acid, another B vitamin, did not appear to affect the risk of Alzheimer’s disease.
The authors noted that more research must be done to uncover the role of B vitamins and other nutrients in the onset of Alzheimer’s disease. Most dietary experts recommend a nutrient-rich diet containing an array of vitamins and minerals to protect against Alzheimer’s and other chronic ailments. In addition to a balanced diet, studies have found that moderate exercise, along with keeping weight under control and cholesterol and blood pressure in check during midlife, may be important for a healthy old age.
B. Hooshman, MD, MSc; A. Solomon, MD, PhD; J. Kareholt, PhD; et al: “Homocysteine and Holotranscobalamin and the Risk of Alzheimer Disease.” Neurology ,Vol. 75, October 19, 2010, pages 1408-1414.
Sudha Seshadri, MD: “Beauty and the Best: B12, Homocysteine, and the Brain: A Bemusing Saga!” (editorial). Neurology, Vol. 75, Oct. 19, 2010, pages 1402-1403.