The vitamin E isoforms α-tocopherol and γ-tocopherol have opposite associations with spirometric parameters: the CARDIA study
1 Division of Allergy and Immunology, Feinberg School of Medicine, Northwestern University, McGaw M304, 240 E. Huron, Chicago, IL, 60611, USA
2 The Ann and Robert H. Lurie Children’s Hospital of Chicago, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
3 Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
4 Division of Epidemiology and Community Health, University of Minnesota, School of Public Health, Minneapolis, MN 55454, USA
5 Department of Nutrition, School of Medicine, University of Oslo, Oslo, Norway
6 Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA
7 Division of Pulmonary and Critical Care Medicine, University of New Mexico, Albuquerque, NM 87131, USA
Respiratory Research 2014, 15:31 doi:10.1186/1465-9921-15-31Published: 15 March 2014
Clinical studies of the associations of vitamin E with lung function have reported conflicting results. However, these reports primarily examine the α-tocopherol isoform of vitamin E and have not included the isoform γ-tocopherol which we recently demonstrated in vitro opposes the function of α-tocopherol. We previously demonstrated, in vitro and in animal studies, that the vitamin E isoform α-tocopherol protects, but the isoform γ-tocopherol promotes lung inflammation and airway hyperresponsiveness.
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.
In cross-sectional regression analysis at year 0, higher γ-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 α-tocopherol associated with higher FVC (p = 0.04 in blacks and whites and p = 0.01 in all participants). In the lowest quartile of α-tocopherol, higher γ-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 γ-tocopherol, higher α-tocopherol associated with a higher FEV1 (p = 0.03) in blacks. Serum γ-tocopherol >10 μM was associated with a 175–545 ml lower FEV1 and FVC at ages 21–55 years.
Increasing serum concentrations of γ-tocopherol were associated with lower FEV1 or FVC, whereas increasing serum concentrations of α-tocopherol was associated with higher FEV1 or FVC. Based on the prevalence of serum γ-tocopherol >10 μM 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 γ-tocopherol occur in up to 4.5 million adults in the population.