Source
Department of Public Health, PO Box 41, University of Helsinki, Helsinki, FIN-00014 Finland. harri.hemila@helsinki.fi
Abstract
BACKGROUND:
Vitamin E and beta-carotene affect various measures of immune function and accordingly might influence the predisposition of humans to infections. However, only few controlled trials have tested this hypothesis.
STUDY OBJECTIVE:
To examine whether vitamin E or beta-carotene supplementation affects the risk of pneumonia in a controlled trial.
DESIGN AND SETTING:
The Alpha-Tocopherol Beta-Carotene Cancer Prevention (ATBC) study, a randomized, double-blind, placebo-controlled trial that examined the effects of vitamin E, 50 mg/d, and beta-carotene, 20 mg/d, on lung cancer using a 2 x 2 factorial design. The trial was conducted in the general community in southwestern Finland in 1985 to 1993; the intervention lasted for 6.1 years (median). The hypothesis being tested in the present study was formulated after the trial was closed.
PARTICIPANTS:
ATBC study cohort of 29,133 men aged 50 to 69 years, who smoked at least five cigarettes per day, at baseline.
MAIN OUTCOME MEASURE:
The first occurrence of hospital-treated pneumonia was retrieved from the national hospital discharge register (898 cases).
RESULTS:
Vitamin E supplementation had no overall effect on the incidence of pneumonia (relative risk [RR], 1.00; 95% confidence interval [CI], 0.88 to 1.14) nor had beta-carotene supplementation (RR, 0.98; 95% CI, 0.85 to 1.11). Nevertheless, the age of smoking initiation was a highly significant modifying factor. Among subjects who had initiated smoking at a later age (> or =21 years; n = 7,469 with 196 pneumonia cases), vitamin E supplementation decreased the risk of pneumonia (RR, 0.65; 95% CI, 0.49 to 0.86), whereas beta-carotene supplementation increased the risk (RR, 1.42; 95% CI, 1.07 to 1.89).
CONCLUSIONS:
Data from this large controlled trial suggest that vitamin E and beta-carotene supplementation have no overall effect on the risk of hospital-treated pneumonia in older male smokers, but our subgroup finding that vitamin E seemed to benefit subjects who initiated smoking at a later age warrants further investigation.