Minimal evidence that vitamin supplementation prevents cardiovascular disease

Kritharides, Leonard PhD, FRACP, FAHA

Department of Cardiology, Concord Hospital, University of Sydney and Centre for Vascular Research, University of New South Wales; Sydney, Australia

Abstracted from:Morris CD, Carson S. Routine vitamin supplementation to prevent cardiovascular disease: a summary of the evidence for the U.S. Preventive Services Task Force. Ann Intern Med 2003; 139: 56-70 .

Sources of funding: The study was funded by the Agency for Healthcare Research and Quality.

Correspondence to: Cynthia D Morris, Department of Medical Informatics and Clinical Epidemiology, Oregon Health and Science University Evidence-based Practice Center, Sam Jackson Park Road, Portland, Oregon, USA

Abstract provided by Bazian Ltd, London

Evidence-based Healthcare 8(1):p 24-26, March 2004.

BACKGROUND

The effects of vitamin supplementation on the incidence and progression of cardiovascular events in a general adult population are unknown.

OBJECTIVE

To assess the effect of vitamin supplementation on the prevention of cardiovascular disease.

METHOD

Systematic review with narrative synthesis.

SEARCH STRATEGY

MEDLINE and the Cochrane Controlled Trials Registry searched September 2001 for English language studies; hand searches of bibliographies and contact with experts.

INCLUSION/EXCLUSION CRITERIA

All randomised trials and prospective cohort studies from European and US populations reporting on non-dietary vitamin supplementation and cardiovascular events were included. Studies were excluded if they: took place in an acute care setting; addressed vitamin deficiency disease or were conducted in specific populations (e.g. people with end-stage renal disease).

OUTCOMES

Cardiovascular events, myocardial infarction, restenosis, change in angina, cardiovascular mortality and all-cause mortality. Primary and secondary prevention trials were assessed and analysed separately.

MAIN RESULTS

No randomised controlled trials evaluating prevention of cardiovascular events by supplementation with vitamins A or C were found. Vitamin E: Two RCTs (the first with 27,271 male smokers aged 50 to 69 years and the second with 4495 men and women aged > 50 years with one of the known cardiovascular disease risk factors) found that vitamin E supplementation alone had no significant effect on primary prevention of cardiovascular disease. Of seven RCTs assessing vitamin E supplementation for secondary prevention of cardiovascular disease outcomes, no high-quality studies demonstrated a beneficial effect. β-carotene: Four RCTs found that β-carotene supplementation had no effect on primary prevention of cardiovascular disease or death. Antioxidant vitamin combinations: Six RCTs (β-carotene plus retinol versus placebo [1 RCT]; vitamin C plus vitamin E plus β-carotene versus placebo or no antioxidant [3 RCTs]; vitamin C plus vitamin E plus β-carotene plus selenium versus placebo [1 RCT]; vitamin C plus vitamin E versus placebo [1 RCT]) found that combination antioxidant therapy had no effect on either primary or secondary prevention of major cardiovascular outcomes. Multivitamin combinations: One RCT found that a combination of folic acid plus vitamin B12 plus pyridoxine administered after successful coronary angioplasty significantly reduced the rate of restenosis and the need for revascularization compared with placebo, although there was no significant effect on myocardial infarction or cardiovascular mortality.

AUTHORS' CONCLUSIONS

Evidence that vitamin supplementation is beneficial in the primary or secondary prevention of cardiovascular disease is minimal.