Primary Prevention

The results of most primary prevention trials have not been encouraging (Table 1). For example, in the Finnish Alpha-Tocopherol Beta-Carotene Cancer Prevention (ATBC) study, approximately 30 000 male smokers received vitamin E (50 mg/day of a-tocopherol), ^-carotene (20 mg/day), both, or an

Table 1 Summary of large intervention trials (>1000 subjects) investigating the role of antioxidants and CVD in primary prevention

Trial Characteristics of Sex Length of Treatment Effect of antioxidant subjects follow-up supplementation

(years)

ATBC 29133 smokers, Finland

Male

CARET 14 254 smokers, 4 060 Male and Female asbestos workers, United States

LCPS 29584 poorly Male and Female nourished, China

22 071 physicians, United States

Male

4 495 with one or more Male and Female CVD risk factors, Italy

SCPS 1720 with recent Male and Female nonmelanoma skin cancer, Australia VACPII 1 204 former asbestos Male and Female workers, Australia

31 32

39876, United States

Female

50 mg «-tocopherol and/or 20 mg ^-carotene

30 mg ^-carotene and 25000IU retinol

15 mg ^-carotene, 30 mg «-tocopherol, and 50 mg selenium

50 mg ^-carotene and/or aspirin (alternate days)

Low-dose aspirin and/or 300 mg a-tocopherol

50 mg ^-carotene

30 mg ^-carotene or 25000 IU retinol (no placebo group) 50 mg ^-carotene (alternate days)

No significant effect on fatal or nonfatal-CHD or total strokes with either supplement Increase in deaths from hemorrhagic stroke in vitamin E group Increase in hemorrhagic stroke (+62%) and total mortality (+8%) in ^-carotene group Increase in deaths from CVD (+26%) (terminated early) Small decline in total mortality (+9%) Reduction in deaths from stroke in men (-55%) but not women No effect on fatal or nonfatal myocardial infarction or stroke No effect on CVD deaths or events (but inadequate power due to premature interruption of trial) No effect on CVD mortality

No effect of ^-carotene on CHD deaths

No effect on fatal or nonfatal CVD

ATBC, Alpha Tocopherol Beta Carotene Prevention Study; CARET, Beta Carotene and Retinol Efficacy Trial; LCPS, Linxian Cancer Prevention Study; PHS, Physicians Health Study; PPP, Primary Prevention Project; SCPS, Skin Cancer Prevention Study; VACP, Vitamin A and Cancer Prevention; WHS, Women's Health Study; CHD, Coronary Heart Disease; CVD, Cardiovascular disease.

inactive substance (placebo) for approximately 6 years. There was no reduction in risk of major coronary events with any of the treatments despite a 50% increase in blood vitamin E concentrations and a 17-fold increase in ^-carotene levels. Moreover, with vitamin E supplementation, there was an unexpected increase in risk of death from hemorrhagic stroke and a small but significant increase in mortality from all causes with ^-carotene supplementation (RR, 1.08; 95% confidence interval (CI), 1-16). An increase in CVD deaths was also observed in the Beta-Carotene and Retinol Efficacy Trial (CARET), which tested the effects of combined treatment with ^-carotene (30mg/day) and retinyl palmitate (25 000 IU/day) in 18 000 men and women with a history of cigarette smoking or occupational exposure to asbestos compared to the placebo group (RR, 1.26; 95% CI, 0.99-1.61).

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