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B Vitamins May Not Boost Mental Skills

No Gains Seen in 2-Year Study of Healthy Adults Aged 65 & Older

Medically Reviewed by Louise Chang, MD on June 28, 2006
From the WebMD Archives

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

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

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

Jennifer McMahon, PhD, and colleagues at New Zealand's University of Otagodid the study. The editorialist questioning it was Robert Clarke, MD, ofUniversity 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 homocysteinemight be a risk factor for cognitive decline in aging, note McMahon and colleagues. They wantedto test that theory.

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

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

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

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

No Brain Boost

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

"Overall, there were no significant differences between the vitamin andplacebo groups in the scores on tests of cognition," write McMahon andcolleagues. "The results of this trial do not show that homocysteinelowering with B vitamins improves cognitive performance," at least inhealthy 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 fewparticipants, the duration of treatment was too short, and cognitive functionscores in controls (the comparison group) remained intact throughout the trial,it lacked the statistical power to refute the homocysteine hypothesis ofdementia."

Show Sources

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.

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