Numerous studies suggest that B vitamins may be good for the brain and help to preserve memory in old age. Now a new report shows that supplements of three B vitamins – folic acid, vitamin B6 and vitamin B12 – may help to keep brain areas critical for memory and thinking in good health in seniors with mild cognitive impairment, a form of memory loss that can lead to Alzheimer’s disease.
There are many types of B vitamins, and all are important for the healthy functioning of the brain and nervous system. After age 50, some people have trouble absorbing B vitamins from foods, particularly vitamin B12, and supplements are recommended.
For the study, researchers at Oxford University looked at a daily regimen of the B vitamins in men and women over 70 who had mild cognitive impairment, a risk factor for Alzheimer’s. Some of the participants got the vitamins – 0.8 milligrams of folic acid, 20 milligrams of vitamin B6, and 0.5 milligrams of vitamin B12 – while others got a placebo. In earlier research, the researchers had found that this regimen slowed overall shrinkage of the brain, a sign of Alzheimer’s and worsening brain function, over a two-year period.
In the current study, the researchers found that treatment with the B vitamins reduced shrinkage of brain areas critical for thinking and memory by as much as seven-fold. The benefits were pronounced in the gray matter in the hippocampus and medial temporal lobe of the brain, an area specifically targeted by Alzheimer’s disease.
But the B vitamins were not effective in everyone. Rather, they had protective effects specifically in those with high blood levels homocysteine, an inflammatory amino acid linked to heart disease and brain wasting. Vitamins B6, B12 and folic acid, taken together, can dramatically lower levels of the amino acid.
People with Alzheimer's often have high levels of homocysteine, and one large study found that high levels of the amino acid were associated with a two-fold increased risk of the disease. Research in animals suggests that high levels of homocysteine and low levels of folic acid may make brain cells more vulnerable to damage from beta-amyloid, a toxic protein that is a hallmark of Alzheimer's, and homocysteine itself may be directly toxic to brain cells.
But in a rigorous study from 2008 of over 400 men and women with mid-stage Alzheimer’s disease, the B vitamins reduced homocysteine levels by almost a third, but had no benefits in slowing cognitive decline. It was unclear why the B vitamins did not have benefits for the brain, despite lowering homocysteine levels, but it may be that people with Alzheimer's disease are already far advanced in the course of their illness, and that vitamins will do little to reverse the damage that's been done.
The researchers believe that B vitamins may be most effective early in the Alzheimer’s disease process, which may occur 10 to 20 years before symptoms become apparent. They plan to conduct additional studies to examine the effects of B vitamins on those with high homocysteine levels to determine whether the nutrients can help prevent progression to dementia and to better understand the links between vitamin levels and brain health.
In the meantime, your best bet may be to follow a heart-healthy diet rich in fruits, vegetables and whole grains to help maintain brain health. B vitamins are found in a variety of foods, including meats like turkey and tuna, as well as potatoes, lentils, bananas and whole grains. Cereals and breads are routinely fortified with folic acid. In addition, regular exercise and mental and social stimulation is thought to be critical to keeping the mind active and alert into old age.
Source: Gwenaelle Douaud, Helga Refsum, Celeste A. de Jager, et al: “Preventing Alzheimer’s disease-related gray matter atrophy by B-vitamin treatment.” Proceedings of the National Academy of Science, May 2013.