29 September 2010

High doses of B vitamins slow rate of shrinking brain

Unfortunately, getting older comes with a common consequence affecting up to 16 percent of elderly people – gradual reduction in brain size, which is associated with problems in learning and memory. However, a new study reports that daily supplementation with high doses of B vitamins may help slow the rate of brain degeneration.

Oxford researchers gave 168 individuals over the age of 70 supplements containing high doses of folic acid (0.8 milligrams per day), B6 (20 milligrams per day) and B12 (0.5 milligrams per day), or a placebo as part of a randomized, double-blind controlled trial. Then, following two years of the supplementation program, the participants’ brains were assessed using serial volumetric magnetic resonance imaging scans.

The researchers reported their results in the September issue of PLoS One: the rate of brain shrinkage, or atrophy, in the group taking the supplements was 53 percent lower in comparison to the group taking the placebo. Their conclusion was that the high doses of B vitamins slowed the rate of brain shrinkage in elderly with mild cognitive impairment.

According to the authors, however, it is still unclear which vitamin provided the greatest benefit for the brain. They found that the reduced rate of brain atrophy was a result of an increase in either vitamin B12 status or folic acid status, but could not conclude which of the two “vitamins is the most important.”

They added that vitamin B6 may be less important for brain health since there was a, “lack of association of atrophy with the change in cystathione levels, a marker of vitamin B6 status.”

Folic acid and vitamin B12 play a role in protecting the brain, most likely because their presence helps to lower the concentration of the amino acid homocysteine in plasma. Higher levels of homocysteine are a risk factor associated with smaller brain size as well as problems with learning and memory — as well as related to poor heart and cardiovascular health.

The study adds to emerging evidence that supplementation with B vitamins may be a convenient way for elderly to help support memory and learning.

Source: Smith AD, Smith SM, de Jager CA et al. Homocysteine-lowering by B vitamins slows the rate of accelerated brain atrophy in mild cognitive impairment: a randomized controlled trial. PLoS One 2010;5:e12244.

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