Vitamin E supplementation and pneumonia risk in males who initiated smoking at an early age: effect modification by body weight and dietary vitamin C
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.Trial registration: ClinicalTrials.gov NCT00342992.
Author: Harri Hemila and Jaakko Kaprio
Credits/Source: Nutrition Journal 2008, 7:33
Published on: 2008-11-19
Copyright by the authors listed above - made available via BioMedCentral (Open Access). Please
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