The vitamin E isoforms α-tocopherol and γ-tocopherol have opposite associations with spirometric parameters: the CARDIA study

Background: Clinical studies of the associations of vitamin E with lung function have reported conflicting results. However, these reports primarily examine the alpha-tocopherol isoform of vitamin E and have not included the isoform.-tocopherol which we recently demonstrated in vitro opposes the function of a-tocopherol. We previously demonstrated, in vitro and in animal studies, that the vitamin E isoform a-tocopherol protects, but the isoform.-tocopherol promotes lung inflammation and airway hyperresponsiveness. Methods: To translate these findings to humans, we conducted analysis of 4526 adults in the Coronary Artery Risk Development in Young Adults (CARDIA) multi-center cohort with available spirometry and tocopherol data in blacks and whites. Spirometry was obtained at years 0, 5, 10, and 20 and serum tocopherol was from years 0, 7 and 15 of CARDIA. Results: In cross-sectional regression analysis at year 0, higher.-tocopherol associated with lower FEV1 (p = 0.03 in blacks and p = 0.01 in all participants) and FVC (p = 0.01 in blacks, p = 0.05 in whites, and p = 0.005 in all participants), whereas higher a-tocopherol associated with higher FVC (p = 0.04 in blacks and whites and p = 0.01 in all participants). In the lowest quartile of a-tocopherol, higher.-tocopherol associated with a lower FEV1 (p = 0.05 in blacks and p = 0.02 in all participants). In contrast, in the lowest quartile of.-tocopherol, higher a-tocopherol associated with a higher FEV1 (p = 0.03) in blacks. Serum.-tocopherol > 10 mu M was associated with a 175-545 ml lower FEV1 and FVC at ages 21-55 years. Conclusion: Increasing serum concentrations of.-tocopherol were associated with lower FEV1 or FVC, whereas increasing serum concentrations of a-tocopherol was associated with higher FEV1 or FVC. Based on the prevalence of serum.-tocopherol > 10 mu M in adults in CARDIA and the adult U. S. population in the 2011 census, we expect that the lower FEV1 and FVC at these concentrations of serum.-tocopherol occur in up to 4.5 million adults in the population.