B Vitamins May Not Boost Mental Skills

摘要：Mental Edge。No Brain BoostAverage homocysteine levels fell in the vitamin group but not in the placebo group。...

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June 28, 2006 -- If you're hoping folate and vitamin B-12 supplements will give you a mental boost, you might want to think again.

New research from New Zealand shows that folate and vitamin B-12 supplements don't appear to improve mental test scores in healthy adults aged 65 and older.

The findings appear in The New England Journal of Medicine. An editorial in the same issue of the journal questions the study, saying it may have been too short to yield any brain benefits.

Jennifer McMahon, PhD, and colleagues at New Zealand's University of Otago did the study. The editorialist questioning it was Robert Clarke, MD, of University of Oxford in England.

Mental Edge?

McMahon's team studied 276 healthy adults aged 65 and older in New Zealand. Participants all had high blood levels of a chemical called homocysteine.

Observational studies have shown that high blood levels of homocysteine might be a risk factor for cognitive decline in agingaging, note McMahon and colleagues. They wanted to test that theory.

First, participants took tests of mental skills including memory, attention, and learning. None showed signs of dementiadementia.

Next, they were split into two groups with similar average homocysteine levels.

For the next two years, everyone in the test group took a daily capsule containing three B vitamins: folate (1 milligram), vitamin B12 (1/2 milligram), and vitamin B-6 (10 milligrams). Those vitamins are often recommended to curb elevated homocysteine in blood.

For comparison, the other group took placebo pills lacking vitamins or other active ingredients. Participants didn't know whether they were taking the vitamins or the placebo. None were taking supplements containing the three B vitamins before the study.

No Brain Boost

Average homocysteine levels fell in the vitamin group but not in the placebo group. However, lower homocysteine levels didn't mean higher mental test scores. Scores generally held steady in both groups.

"Overall, there were no significant differences between the vitamin and placebo groups in the scores on tests of cognition," write McMahon and colleagues. "The results of this trial do not show that homocysteine lowering with B vitamins improves cognitive performance," at least in healthy adults aged 65 and older.

Clarke, who didn't work on McMahon's study, disagrees.

In his editorial, Clarke writes that "since the study included too few participants, the duration of treatment was too short, and cognitive function scores in controls (the comparison group) remained intact throughout the trial, it lacked the statistical power to refute the homocysteine hypothesis of dementia."

SOURCES: McMahon, J. The New England Journal of Medicine, June 29, 2006; vol 354: pp 2764-2772. Clarke, R. The New England Journal of Medicine, June 29, 2006; vol 354: pp 2817-2819.

发布日期：2006-7-4

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