Modification of the effect of vitamin E supplementation on the mortality of male smokers by age and dietary vitamin C.
The Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study (1985-1993) recruited 29,133 Finnish male cigarette smokers, finding that vitamin E supplementation had no overall effect on mortality. The authors of this paper found that the effect of vitamin E on respiratory infections in ATBC Study participants was modified by age, smoking, and dietary vitamin C intake; therefore, they examined whether the effect of vitamin E supplementation on mortality is modified by the same variables. During a median follow-up time of 6.1 years, 3,571 deaths occurred. Age and dietary vitamin C intake had a second-order interaction with vitamin E supplementation of 50 mg/day. Among participants with a dietary vitamin C intake above the median of 90 mg/day, vitamin E increased mortality among those aged 50-62 years by 19% (95% confidence interval: 5, 35), whereas vitamin E decreased mortality among those aged 66-69 years by 41% (95% CI: -56, -21). Vitamin E had no effect on participants who had a dietary vitamin C intake below the median. Smoking quantity did not modify the effect of vitamin E. This study provides strong evidence that the effect of vitamin E supplementation on mortality varies between different population groups. Further study is needed to confirm this heterogeneity.
Hemilä
Harri
H
Department of Public Health, University of Helsinki, Finland. harri.hemila@helsinki.fi
Kaprio
Jaakko
J
D000368:Aged; D000975:Antioxidants / Q000008:administration & dosage; D001205:Ascorbic Acid / Q000008:administration & dosage*; D016001:Confidence Intervals; D019587:Dietary Supplements; D005387:Finland / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress / Q000187:drug effects; D016016:Proportional Hazards Models; D012907:Smoking / Q000401:mortality*; D014810:Vitamin E / Q000008:administration & dosage*
D000975:Antioxidants; D014810:Vitamin E; D001205:Ascorbic Acid