Isoforms of vitamin E (specifically alpha- and gamma-tocopherol) have shown differential effects on in vivo mouse models of allergic inflammation and adult-onset asthma in humans. We hypothesized that maternal postpartum vitamin E isoforms would show differential associations with early life childhood respiratory outcomes.
We conducted a prospective nested study of the INSPIRE birth cohort of 651 children with maternal postpartum plasma vitamin E isoforms measured at study enrollment. We ascertained the outcome of recurrent wheezing requiring asthma medication at two years of life using validated questionnaires. We evaluated for association with, and for interaction between, alpha- and gamma-tocopherol concentrations and recurrent wheezing, while adjusting for covariates.
Median age of the children at time of maternal sample collection was 50 days [IQR 16,81]; 47% were female and 61% were white. Children with two year wheezing (N=174; 27%) had mothers with significantly lower postpartum concentrations of plasma alpha-tocopherol (68 μmol/L [IQR:42,96]) compared to those who did not (75 μmol/L [IQR:50,106]), p=0.021. In multivariable regression analysis for interaction, the relationship of alpha-tocopherol with wheezing was modified by gamma-tocopherol concentration in tertiles (main effect of alpha tocopherol p=0.014, interaction p=0.06). At the highest tertile of gamma tocopherol, the protective association of alpha tocopherol on child wheezing was modified.
In this cohort, increasing maternal postpartum plasma alpha-tocopherol isoform concentration was associated with decreased likelihood of wheezing requiring asthma medications at two years. This protective association appeared to be attenuated at high concentrations of gamma-tocopherol.