Though B vitamins have some health benefits, a study published in the August 20 issue of JAMA finds that they are not an effective means of preventing death or cardiovascular events in patients with coronary artery disease.
To motivate this large randomized trial, researcher Marta Ebbing, M.D. (Haukeland University Hospital, Bergen, Norway) and colleagues reference previous studies that have found an association between the risk of coronary artery disease and stroke and the concentration of total homocysteine in blood. It is also known that B-vitamin deficiencies can result in elevated total homocysteine levels, and plasma total homocysteine levels can be reduced if a person orally takes folic acid and vitamin B12. The authors set out, “To evaluate the effects of homocysteine-lowering treatment with folic acid plus vitamin B12 on mortality and cardiovascular events.”
The randomized controlled study consisted of 3,096 patients in two Norwegian hospitals between 1999 and 2006. Randomization placed patients in one of four groups that received a daily oral dose of:
- 0.8mg folic acid plus 0.4mg vitamin B12 plus 40mg vitamin B6 – 772 patients,
- 0.8mg folic acid plus 0.4mg vitamin B12 – 772 patients,
- 40mg vitamin B6 – 772 patients,
- Or placebo – 780 patients.
After one month, one year, and at the end of the study, patients were to follow-up with the researchers by completing an interview, a clinical examination, and a blood test. The primary end point (main outcome measure) on which the researchers focused was a composite of all-cause death, nonfatal acute myocardial infarction (heart attack), acute hospitalization for unstable angina pectoris, and nonfatal thromboembolic stroke.
It is important to note that this study was terminated prematurely. Participants became concerned because preliminary results from another Norwegian study suggested that there were no benefits from the treatment and B vitamins were increasing the risk of cancer.
The authors did find, however, that, “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.” Additionally, “During a median (midpoint) 38 months of follow-up, the primary end point was experienced by a total of 422 participants (13.7 percent): 219 participants (14.2 percent) receiving folic acid/vitamin B12 vs. 203 (13.1 percent) not receiving such treatment and 200 participants (13.0 percent) receiving vitamin B6 vs. 222 (14.3 percent) not receiving vitamin B6.”
Concluding, the authors write that, “We could not detect any preventive effect of intervention with folic acid plus vitamin B12 or with vitamin B6 on mortality or major cardiovascular events among patients with stable coronary artery disease undergoing intensive conventional treatment. 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.”
“Our findings do not support the use of B vitamins as secondary prevention in patients with coronary artery disease.”
Mortality and Cardiovascular Events in Patients Treated With Homocysteine-Lowering B Vitamins After Coronary Angiography: A Randomized Controlled Trial
Marta Ebbing; Øyvind Bleie; Per Magne Ueland; Jan Erik Nordrehaug; Dennis W. Nilsen; Stein Emil Vollset; Helga Refsum; Eva Kristine Ringdal Pedersen; Ottar Nygård
JAMA(2008). 300[7]: pp. 795-804.
Written by: Peter M Crosta