Associations of alpha and gamma-tocopherol during early life with lung function in childhood

Abstract

Background: Tocopherol isoforms may regulate child lung growth and spirometric measures. Objective: Our aim was to determine the extent to which plasma a-tocopherol (a-T) or g-tocopherol (g-T) isoform levels in early childhood or in utero are associated with childhood lung function. Methods: We included 622 participants in the Project Viva cohort who had lung function at a mid-childhood visit (age 6-10 years). Maternal and child tocopherol isoform levels were measured by HPLC at the second trimester and 3 years of age, respectively. Multivariable linear regression models (adjusted for mid-childhood body mass index z scores, maternal education, smoking in pregnancy, and prenatal particulate matter with diameter of <2.5 micrometers (PM2.5) particulate exposure) stratified by tertiles of child g-T level were used to assess the association of a-T levels with FEV1 and forced vital capacity (FVC) percent predicted. Similarly, models stratified by child a-T tertile evaluated associations of g-T levels with lung function. We performed similar analyses with maternal second trimester tocopherol isoform levels. Results: The median maternal second trimester a-T level was 63 mM (interquartile range 5 47-82). The median early-childhood level was 25 mM (interquartile range 5 20-33 mM). In the lowest tertile of early-childhood g-T, children with a higher a-T level (per 10 mM) had a higher mid-childhood FEV1 percent predicted (b 5 3.09; 95% CI 5 0.58-5.59 and a higher FVC percent predicted (b 5 2.77; 95% CI 5 0.47-5.06). This protective association of a-T was lost at higher g-T levels. We did not see any consistent associations of second trimester levels of either a-T or g-T with mid-childhood FEV1 or FVC. Conclusion: When g-T levels were in the lowest tertile, a higher early-childhood a-T level was associated with better lung function at mid-childhood. Second trimester maternal plasma a-T concentration was 3-fold higher than in the adult nonpregnant female population.