Study objectives: We hypothesized that micronutrient
antioxidant intake may be one factor determining the development of
significant COPD. Vitamin E was administered to smokers to determine if
exhaled ethane was reduced and if ethane correlated with measures of
Study design: Longitudinal placebo
lead-in trial with posttreatment observation period.
Setting: Tucson Veterans Affairs Medical Center.
Participants: Twenty-nine current stable smokers having no
interest in smoking cessation.
Spirometry, exhaled breath ethane measurements, and vitamin E andβ
-carotene plasma levels followed by 3 weeks of placebo with repeat
plasma vitamin levels and ethane measurements; next, 3 weeks of vitamin
E (dl-α-tocopherol), 400 IU po bid followed by plasma vitamin levels
and breath ethane measurements; finally, 3 weeks without vitamins
followed by breath ethane and plasma vitamin levels.
Results: Vitamin E treatment did not reduce ethane
significantly. Exhaled ethane levels (mean + SD: pm/min/kg) were as
follows: baseline, 7.39 ± 5.39; after run-in period, 6.86 ± 4.09;
after vitamin E, 6.36 ± 3.02; and final, 7.23 ± 4.63. After
vitamin E therapy, a significant negative correlation existed between
exhaled ethane and FEV1/FVC. Pack-years of smoking at
baseline and after vitamin E were significantly associated with ethane
exhaled. Initial lung function was not significantly negatively
associated with vitamin E-induced changes in exhaled ethane but a
negative trend was found.
Conclusions: Vitamin E
alone, unlike the combination of vitamins C, E, and β-carotene,
failed to reduced exhaled ethane in cigarette smokers. Exhaled ethane
was correlated with pack-years of smoking. Smokers whose ethane values
were found to fall the most tended to have better preserved lung