Women who are at high risk for developing heart disease do not see their risk for heart attacks or stroke drop when taking a daily dose of certain vitamins.
New research has found that women who have known risk factors for heart disease who took folic acid and vitamins B6 and B12 daily for seven years experienced the same amount of heart-related health problems as those who took placebos.
The study was published in the Journal of the American Medical Association.
The researchers, led by Dr. Christine M. Albert of Brigham and Women's Hospital and Harvard Medical School, focused on women in their study because previous studies had focused on men. They felt that because the supplements have long been proven to reduce the body's level of the amino acid homocysteine, a known marker for heart disease, they would reduce risk levels for heart attack or stroke.
Indeed, homocysteine levels among women who took the vitamins were more than 18 per cent lower than among those who took placebos.
However, during the course of the seven-year study, 14.9 per cent of the women who took the supplements had at least one cardiovascular event (defined as a heart attack, stroke, heart bypass or death), compared to 14.3 per cent of women who took placebos.
"Our results are consistent with prior randomized trials performed primarily among men with established vascular disease and do not support the use of folic acid and B vitamin supplements as preventive interventions for cardiovascular disease in these high-risk- fortified populations," the authors conclude.
Abstract:
Effect of Folic Acid and B Vitamins on Risk of Cardiovascular Events and Total Mortality Among Women at High Risk for Cardiovascular Disease A Randomized Trial
Christine M. Albert, MD, MPH, Nancy R. Cook, ScD, J. Michael Gaziano, MD, MPH, Elaine Zaharris, BA, Jean MacFadyen, BA, Eleanor Danielson, MIA, Julie E. Buring, ScD, JoAnn E. Manson, MD, DrPH
Context: Recent randomized trials among patients with preexisting cardiovascular disease (CVD) have failed to support benefits of B-vitamin supplementation on cardiovascular risk. Observational data suggest benefits may be greater among women, yet women have been underrepresented in published randomized trials.
Objective: To test whether a combination of folic acid, vitamin B6, and vitamin B12 lowers risk of CVD among high-risk women with and without CVD.
Design, Setting, and Participants: Within an ongoing randomized trial of antioxidant vitamins, 5442 women who were US health professionals aged 42 years or older, with either a history of CVD or 3 or more coronary risk factors, were enrolled in a randomized, double-blind, placebo-controlled trial to receive a combination pill containing folic acid, vitamin B6, and vitamin B12 or a matching placebo, and were treated for 7.3 years from April 1998 through July 2005.
Intervention: Daily intake of a combination pill of 2.5 mg of folic acid, 50 mg of vitamin B6, and 1 mg of vitamin B12.
Main Outcome Measures: A composite outcome of myocardial infarction, stroke, coronary revascularization, or CVD mortality.
Results: Compared with placebo, a total of 796 women experienced a confirmed CVD event (406 in the active group and 390 in the placebo group). Patients receiving active vitamin treatment had similar risk for the composite CVD primary end point (226.9/10 000 person-years vs 219.2/10 000 person-years for the active vs placebo group; relative risk [RR], 1.03; 95% confidence interval [CI], 0.90-1.19; P=.65), as well as for the secondary outcomes including myocardial infarction(34.5/10 000person-years vs39.5/10 000personyears; RR, 0.87; 95% CI, 0.63-1.22; P=.42), stroke (41.9/10 000 person-years vs 36.8/ 10 000person-years;RR,1.14;95%CI, 0.82 1.57;P=.44),andCVDmortality(50.3/10 000 person-years vs 49.6/10 000person-years; RR, 1.01;95%CI,0.76-1.35;P=.93). In a blood substudy, geometricmeanplasma homocysteine level was decreased by 18.5%(95%CI, 12.5%-24.1%; P_.001) in the active group (n=150) over that observed in the placebo group (n=150), for a difference of 2.27 锟絤ol/L (95% CI, 1.54-2.96 锟絤ol/L).
Conclusion: After 7.3 years of treatment and follow-up, a combination pill of folic acid, vitamin B6, and vitamin B12 did not reduce a combined end point of total cardiovascular events among high-risk women, despite significant homocysteine lowering.
