B Vitamins May Not Boost Mental Skills
No Gains Seen in 2-Year Study of Healthy Adults Aged 65 & Older
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
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.
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 aging, 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 dementia.
Next, they were split into two groups with similar average homocysteine
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