Vitamin E supplementation and pneumonia risk in males who initiated smoking at an early age: effect modification by body weight and dietary vitamin C.
BACKGROUND
We had found a 14% higher incidence of pneumonia with vitamin E supplementation in a subgroup of the Alpha-Tocopherol Beta-Carotene Cancer Prevention (ATBC) Study cohort: participants who had initiated smoking by the age of 20 years. In this study, we explored the modification of vitamin E effect by body weight, because the same dose could lead to a greater effect in participants with low body weight.


METHODS
The ATBC Study recruited males aged 50-69 years who smoked at least 5 cigarettes per day at the baseline; it was conducted in southwestern Finland in 1985-1993. The current study was restricted to 21,657 ATBC Study participants who initiated smoking by the age of 20 years; the median follow-up time was 6.0 years. The hospital-diagnosed pneumonia cases were retrieved from the national hospital discharge register (701 cases).


RESULTS
Vitamin E supplementation had no effect on the risk of pneumonia in participants with body weight in a range from 70 to 89 kg (n = 12,495), risk ratio (RR) = 0.99 (95% CI: 0.81 to 1.22). Vitamin E increased the risk of pneumonia in participants with body weight less than 60 kg (n = 1054), RR = 1.61 (1.03 to 2.53), and in participants with body weight over 100 kg (n = 1328), RR = 2.34 (1.07 to 5.08). The harm of vitamin E supplementation was restricted to participants with dietary vitamin C intake above the median.


CONCLUSIONS
Vitamin E supplementation may cause harmful effects on health in certain groups of male smokers. The dose of vitamin E used in the ATBC Study, 50 mg/day, is substantially smaller than conventional vitamin E doses that are considered safe. Our findings should increase caution towards taking vitamin E supplements.


BACKGROUND
ClinicalTrials.gov NCT00342992.
Hemilä
Harri
H
Department of Public Health, University of Helsinki, Helsinki, Finland. harri.hemila@helsinki.fi
Kaprio
Jaakko
J
D000368:Aged; D001205:Ascorbic Acid / Q000008:administration & dosage*; D001835:Body Weight / Q000502:physiology*; D015331:Cohort Studies; D019587:Dietary Supplements; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011014:Pneumonia / Q000453:epidemiology* / Q000209:etiology; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D014810:Vitamin E / Q000008:administration & dosage / Q000009:adverse effects*
D014810:Vitamin E; D001205:Ascorbic Acid