Positive Health Online

Abstract

THE MRC/BHF HEART PROTECTION STUDY COLLABORATIVE GROUP investigated possible long-term (5-year) effects of daily antioxidant vitamin supplementation on adults with cardiovascular disease or diabetes .

Background

Some have suggested that increased consumption of antioxidant vitamins may reduce the occurrence of cardiovascular disease, cancer and other serious illnesses or life-threatening clinical events.

Methodology

This large, long-term, multicentre, randomized, placebo- controlled clinical trial involved 20,536 adults aged 40-80 years with coronary artery disease, other forms of occlusive artery disease or diabetes . Subjects were randomly assigned to receive: 1) dietary supplementation with antioxidant vitamins (600 mg vitamin E, 250 mg vitamin C and 20 mg beta-carotene daily); or 2) matching placebo over a period of 5 years. Outcome measures were the occurrence of major coronary events and fatal or non-fatal vascular events . Results were analysed on an intention-to-treat basis.

Results

83% (average) of subjects in either group remained compliant with treatment during the study. In the vitamin-supplemented group, plasma concentrations of vitamin E (alpha-tocopherol) doubled, vitamin C levels increased by a third and those of beta-carotene increased four-fold . At the end of the study period, no significant differences between the vitamin-supplemented and placebo groups were detected with regard to all-cause mortality (14.1% in the vitamin group, 13.5% in the placebo group) or deaths due to vascular (8.6% versus 8.2%) or non-vascular (5.5% versus 5.3%) causes . Similar numbers of subjects in either group had a non-fatal myocardial infarction or died due to coronary occlusion (10.4% versus 10.2%), had a non-fatal or fatal stroke (5.0% in both groups) or underwent coronary or non-coronary revascularization (10.3% versus 10.6%). There were no differences between the two groups in the first occurrence of any of these “major vascular events” either overall (22.5% in both groups; event rate ratio 1.00) or according to subcategory analysis (fatal or non-fatal vascular events). No differences were detected between the two groups with regard to incidence of cancer or hospitalization for any other non-vascular event .

Conclusion

Supplementation with antioxidant vitamins in this large group of high-risk individuals appeared to be safe and substantially increased blood levels of the vitamins. However, long-term supplementation with antioxidant vitamins had no significant effects on 5-year mortality rates or incidence of vascular events, cancer or any other major outcome .

References

The Heart Protection Study Collaborative Group. MRC/BHF Heart Protection Study of antioxidant vitamin supplementation in 20,536 high-risk individuals: a randomised placebo-controlled trial. Lancet 360 (9326): 23-33. Jul 2002.