Effect of Vitamin E on Exhaled Ethane in Cigarette Smokers: Lung function
Exhaled ethane was negatively associated with FEV1/FVC in general (Fig 3), but this negative correlation achieved statistical significance only after vitamin E intake (Fig 3, center, B). The negative association between exhaled ethane and FEV1 percent predicted was also observed at all time points but never achieved statistical significance.
The relationship between lung function and changes in exhaled ethane after vitamin E alone were not statistically significant (Fig 4), but there appeared to be a negative slope to this relationship.
Evidence of increased lipid peroxidative activity in smokers has been shown by Petruzzelli et al, Karla et al, Morrow et al, by our laboratory,- and by Hoshino et al. This increased free radical activity has been attributed to cigarette smoke, inflammation, and infections. Although cigarette smoking is the major risk factor for the development of COPD, not all cigarette smokers progress to develop clinically significant COPD. It is estimated that 10 to 20% of cigarette smokers will progress to clinically significant COPD.
What factor or factors determine which smokers will be selected to have a rapid decline in lung function have yet to be determined. The role of diet has been studied since antioxidant defenses are believed to be important in protecting the lung from the effects of the high oxidant load to which the lung is exposed. Recent epidemiologic data from Britton et al have supported the notion of antioxidant intake being a factor in the development of lung disease. In that large epidemiologic study of middle-aged people from central England, both vitamin E and vitamin C intake were associated with preservation of lung function. The authors noted that the protective effect of vitamin C was greater than for vitamin E. Another study by Rautalahti et al showed reduced respiratory symptoms being correlated with increased intake of vitamin E and β-carotene. allergy relief
Figure 3. Relationship between exhaled ethane and lung function as measured by FEV1/FVC ratio after placebo run-in period (top, A), after 3 weeks of vitamin E (center, B), and at final visit (bottom, C). There was a negative association between these two variables that was statistically significant after vitamin E supplementation (center, B). See text for discussion.
Figure 4. The relationship between vitamin E-induced changes in exhaled ethane and measurement of lung function was not statistically significant. See Discussion section for details.