B Vitamins/Folic Acid Show Little Effect on Cognitive Function

Dementia rates are rising globally, and the search for a magic bullet to prevent cognitive decline is intensifying. Estimates suggest that the number of people with dementia will double every 20 years, reaching 81 million by 2040. Previous studies have hinted at potential benefits for cognitive function with the B vitamins and folic acid, but a new study has all but eliminated this approach.

Arch Intern Med.

This systematic review of 14 studies of older adults (aged 65-92 years) with normal or impaired cognitive function has shown that supplementation with vitamin B₁₂ or B₆ and/or folic acid had no significant impact on cognitive function ( 2007; 167:21-30).

The 3 trials that looked at vitamin B₆ and the 6 trials that looked at vitamin B₁₂ reported no cognitive benefits at a variety of doses and routes of administration and in diverse patient populations.

Of the 3 trials that looked at folic acid supplementation, 1 trial showed cognitive function benefits in patients with cognitive impairment and low baseline serum folate levels.

A total of 6 trials looked at combinations of vitamins B₁₂ and B₆, and all reported no change in cognitive function. Of note, in 3 of these trials, there was greater improvement in cognitive function reported among the patients receiving placebo.

This systemic review was limited by a lack of clinical data, small sample size, heterogeneity in outcomes, and a paucity of studies that assessed symptoms or clinical outcomes, the investigators, led by Ethan M. Balk, MD, MPH, stressed, noting that about 50 different tests of cognitive function were used in the 14 studies reviewed.

IMWR

“Overall, the evidence is poor and currently inadequate to come to a strong conclusion about the value of B vitamin supplementation to improve cognitive function in the elderly. That said, the evidence does not suggest a benefit of routine supplementation with vitamins B₆ and B₁₂ or folic acid, except possibly of folic acid supplementation for patients with both cognitive impairment and low folic acid levels,” Dr Balk told .

More research is needed to determine which patients, if any, would benefit from vitamin B supplementation and whether this vitamin would improve the clinical signs and symptoms of cognitive impairment, the study investigators conclude.

However, Dr Balk added, “As a general rule, normal doses of B vitamin supplements are known to be safe and well tolerated.”

Key points

• It is estimated that 81 million patients will be affected by dementia by 2040.

• Vitamins B₆ and B₁₂ were found to have no effect on cognitive function at a variety of doses or in combination.

• However, because of insufficient evidence, the jury is still out about the potential impact on cognitive decline.

• In 3 studies, people taking a placebo showed less cognitive decline than those taking B vitamins.