An international team, led by University of Western Australia, has said this was the first time researchers had been able to demonstrate unequivocally that they could reduce the risk of clinically significant depressive symptoms after a stroke.
"Previous work had suggested that certain vitamins could have a role in preventing depression. However, we found that the stroke survivors who took daily folic acid, vitamin B6 and B12 were half as likely to become depressed.
"This is an important finding, as depression is common in stroke survivors - one in three stroke sufferers is affected. We were hoping to find a way to prevent unnecessary suffering and the onset of depression.
"These results open access to a safe, effective and affordable way to manage their risk of depression after stroke," Professor Osvaldo Almeida, who led the team, said. Professor Almeida said previous research had found that B-vitamins could alter the concentration of homocysteine, an amino acid. High concentrations of this amino acid had been linked to depression.
But he cautioned people with pre existing cardiovascular disease against taking high dosages of B-vitamins.
"Taking high doses of B-vitamins has not been adequately studied and may not result in a protective effect. In fact, there is some evidence that the use of these vitamins may cause cardiovascular problems in some circumstances.
"So people who are considering using these vitamins should discuss these issues with their doctor. The protective effect of these vitamins only became apparent after about six years of regular treatment.
"We suspect that this may be due to a slow and gradual change in the vascular system, but further research is require before we can be absolutely sure. At this stage, we cannot extrapolate these benefits to non-stroke survivors," Professor Almeida said.
The research was part of a major 12-year study that looked at the effects of B vitamins in preventing further strokes in stroke survivors, the findings of which are published in the 'Annals of Neurology' journal.