Preventative vitamin treatment may not have the impact on mental function that had been hoped, a new study has concluded.
It had been indicated by earlier research that Vitamins B6, B12 and folic acid could help with loss of brain function in diseases like Alzheimer's and dementia because of their impact on homocysteine levels.
Levels of homocysteine – an amino acid that causes the clogging and stiffening of arteries – were "sharply" reduced in the two year long placebo-controlled trial, but no positive effect on brain function was seen.
"I don't think we can completely discard that theory right now," said Associate Professor C Murray Skeaff, one of the study's authors, "but it certainly puts a chink in the armour."
Authors of the study, which was published in the New England Journal of Medicine, have suggested that high homocysteine levels may be a symptom of health problems – rather than a cause as had been hoped.
Longer studies, which will examine the effects of B vitamins over a lifetime, are underway.