In the study involving 3,096 patients in two Norwegian hospitals between 1999 - 2006, lead researcher Marta Ebbing, M.D. of Haukeland University Hospital, Bergen, Norway randomly assigned patients to four groups, with receiving daily oral dose of folic acid plus vitamin B12 , 0.4mg, plus vitamin B6, 40mg.
The second group was given folic acid plus vitamin B12, third vitamin B6 alone and the fourth group received placebo
According to the authors, observational studies have demonstrated that the concentration of total homocysteine (chemical compound) in blood is associated with risk of coronary artery disease and stroke.
"Mean (average) plasma total homocysteine concentration was reduced by 30 percent after 1 year of treatment in the groups receiving folic acid and vitamin B12," wrote the authors.
During 38 months of follow-up, the primary end point was experienced by a total of 422 participants with 219 participants receiving folic acid/vitamin B12 compared to 203 not receiving such treatment.
On the other hand, 200 participants receiving vitamin B6 benefited from the treatment, compared to 222 (14.3 percent) not receiving vitamin B6.
"We found a numerically lower incidence of stroke and higher incidence of cancer in the groups receiving folic acid, but these observations were not statistically significant," the authors conclude.
"Our findings do not support the use of B vitamins as secondary prevention in patients with coronary artery disease," the authors added.
The study is published in the August 20 issue of JAMA.