Interaction of vitamin E isoforms on asthma and allergic airway disease

Prospective epidemiological studies, observational cross-sectional studies and some randomised prevention trials have demonstrated inconsistent findings of the impact of vitamin E on asthma risk. The goals of this study were to explore whether this differing association of vitamin E on asthma risk is due to an interaction of vitamin E isoforms. To address this question, in a population-based asthma incidence study we assessed the interaction between the plasma concentrations of vitamin E isoforms alpha-tocopherol and gamma-tocopherol on asthma risk. Second, to understand the mechanisms of any interaction of these isoforms, we conducted experimental supplementation of alpha-tocopherol and gamma-tocopherol isoforms in mice on the outcome of allergic airway inflammation. We found that in the highest gamma-tocopherol tertile, low levels of alpha-tocopherol were associated with increased asthma risk, while highest tertile alpha-tocopherol levels trended to be protective. Similarly, in a mouse model of asthma, diet supplementation with alpha-tocopherol decreased lung inflammation in response to house dust mite (HDM) challenge. In contrast, diet supplementation with gamma-tocopherol increased lung inflammation in response to HDM. These human and animal studies provide evidence for the competing effects of the vitamin E isoforms, in physiological concentrations, on asthma and allergic airway disease.