Vitamin B Effects on Cognitive Performance Uncertain

A new study suggests that vitamin B12 and folate supplements may not actually reduce the risk of memory and thinking problems.

Researchers at Wageningen University (The Netherlands) conducted a double-blind, randomized, placebo-controlled trial to investigate the effects of two-year folic acid and vitamin B12 supplementation on the cognitive performance of elderly people with elevated homocysteine (Hcy) levels, a potential modifiable dementia risk factor. The study included 2,919 elderly participants (65 years and older), who received a daily tablet with 400 µg folic acid and 500 µg vitamin B12, or placebo; both tablets contained 15 µg vitamin D3. Global cognitive functioning was assessed by memory and thinking skills tests at the beginning and end of the study.

The results showed that while mean Hcy concentrations decreased by 5.0 µmol/L in the vitamin B12 group and 1.3 µmol/L in the placebo group, cognitive domain scores did not differ over time between the two groups. The researchers added that while it is possible that vitamin B12 and folate supplements could slightly slow the rate of decline of global cognition, the small difference may be attributable to chance alone. The study was published on November 12, 2014, in Neurology.

“Since homocysteine levels can be lowered with folic acid and vitamin B12 supplements, the hope has been that taking these vitamins could also reduce the risk of memory loss and Alzheimer's disease,” said lead author Rosalie Dhonukshe-Rutten, PhD. “although the homocysteine levels decreased by more in the group taking the B vitamins than in the group taking the placebo, unfortunately there was no difference between the two groups in the scores on the thinking and memory tests.”

A high level of homocysteine in the blood makes a person more prone to endothelial cell injury, which leads to inflammation in the blood vessels that could lead to ischemic injury. High Hcy is therefore a possible risk factor for coronary artery disease (CAD), thrombosis, neuropsychiatric illness, and fractures. Previous studies have also shown links between higher Hcy levels, memory loss, and Alzheimer's disease.

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