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.

Abstract

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 (34.5/10,000 person-years vs 39.5/10,000 person-years; RR, 0.87; 95% CI, 0.63-1.22; P = .42), stroke (41.9/10,000 person-years vs 36.8/10,000 person-years; RR, 1.14; 95% CI, 0.82-1.57; P = .44), and CVD mortality (50.3/10,000 person-years vs 49.6/10,000 person-years; RR, 1.01; 95% CI, 0.76-1.35; P = .93). In a blood substudy, geometric mean plasma 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 micromol/L (95% CI, 1.54-2.96 micromol/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.

TRIAL REGISTRATION:

clinicaltrials.gov Identifier: NCT00000541.

• Authors: Christine M Albert, Nancy R Cook, J Michael Gaziano, Elaine Zaharris, Jean MacFadyen, Eleanor Danielson, Julie E Buring, JoAnn E Manson
• Journal: JAMA (JAMA) Vol. 299 Issue 17 Pg. 2027-36 (May 07 2008) ISSN: 1538-3598 [Electronic] United States
• PMID: 18460663 (Publication Type: Journal Article, Randomized Controlled Trial, Research Support, N.I.H., Extramural)

Chemical References

• Drug Combinations
• Homocysteine
• Vitamin B Complex
• Vitamin B 6
• Folic Acid
• Vitamin B 12

Topics

• Adult
• Aged
• Cardiovascular Diseases (mortality, prevention & control)
• Dietary Supplements
• Double-Blind Method
• Drug Combinations
• Female
• Folic Acid (blood, therapeutic use)
• Homocysteine (blood)
• Humans
• Middle Aged
• Risk
• Vitamin B 12 (therapeutic use)
• Vitamin B 6 (therapeutic use)
• Vitamin B Complex (therapeutic use)