We investigated the association between serum vitamin E and AR in children aged 6–14 years. The levels of vitamin E in children with AR were lower than normal children, and an association was found between vitamin E levels and AR. The results remained significant even after adjusting for confounding factors related to vitamin E.
The relationship between AR prevalence and serum vitamin E levels is controversial in existing studies. In several cohort studies, it was found that maternal vitamin E intake from food during pregnancy was inversely related to the risk of AR in children [14, 15]. Similarly, high-dose vitamin E supplementation in combination with routine treatment may be valuable to improving symptoms in patients with seasonal allergic rhinitis . In contrast, some reports found no association between AR and vitamin E intake [16, 17]. The differences may derive from the following reasons: 1) Children may need more supplementation in the vitamin E due to their faster metabolic rate 2) the discrepancy in dietary structure and nutritional status of different regions.
Obtaining a thorough history and physical examination as well as identifying specific allergic triggers are required to establish the clinical diagnosis of allergic rhinitis. Allergen-specific IgE tests and skin prick tests are the main methods for determining allergens. Each has its advantages and cannot be replaced by the other. Therefore, we analyzed the correlation between the two results and serum vitamin E levels of children with AR, attempting to link vitamin E with the diagnosis of AR. In this study, 62 children with AR were found to be allergic to dermatophagoids. D.farinais, the most common allergen in children with AR, followed by cockroach and birch. At the same time, our results showed a significant inverse correlation between serum vitamin E levels and Df SPT grade.
McCann W A et al.  demonstrated the diagnostic value of serum sIgE in allergic diseases, with the sensitivity fluctuating between 84% and 95% and the specificity fluctuating between 85% and 94%. Given that serum immunoglobulin E (IgE) can be synthesized even before clinical symptoms occur, and elevated IgE levels are one of the indicators of type I allergic reactions, we measured the serum tIgE and sIgE levels and found that sIgE was negatively correlated with vitamin E. Correspondingly, Fogarty etal.  revealed that higher-dose of vitamin E intake were associated with lower serum IgE concentrations and a lower frequency of allergic sensitization. Because of the diagnostic value of SPT and sIgE in AR, we investigated the association between SPT and sIgE and serum vitamin E and found a statistically significant inverse correlation, which may reflect the inverse correlation between serum vitamin E level and AR. However, the correlation between tIgE and vitamin E was not statistically significant. This may be because many factors can lead to increasing tIgE levels in the body, and approximately one-third of patients with AR were in the normal range.
Vitamin E, a fat-soluble vitamin, is one of the most important antioxidants and is closely correlated with immune function . At the same time, the production of reactive oxygen species (ROS) and oxidative stress are related to allergic inflammation. Vitamin E metabolites have been identified as potential regulator associated with immune, inflammatory responses, lipid metabolism, neuronal cell protection and vessel homeostasis in vivo [21, 22]. Although vitamin E has a positive antioxidant effect and oxidative stress has a role in the development of AR, the association between vitamin E and AR has not been proven beyond any reasonable doubt. Our data provide strong evidence for the link between vitamin E and allergic rhinitis. T helper 2 (Th2) cytokines interleukin-4 (IL-4), IL-5, IL-9 and IL-13 play key roles in AR propagation and in the maintenance of allergic inflammation, while T helper 1 (Th1) cytokines play the opposite role. In vitro, vitamin E promotes the secretion of Th1 cytokine and inhibits Th2 cytokines secretion [23, 24]. Vitamin E also reduces the secretion of IL-4 in human peripheral blood T cells . IL-4 can promote the production of IgE antibodies by B-cells and is one of the key cytokines in the development of allergic inflammation. In addition, vitamin E inhibits the activity of cyclooxygenase, indirectly inhibits the synthesis of arachidonic acid-derived prostaglandin E2 (PGE2), and PGE2 has been involved in shifting the balance of Th1/Th2 cells and their cytokines towards a Th2 profile [26, 27]. In conclusion, these findings support that vitamin E might be protective against allergic sensitization.
Our study showed no significant inverse correlation between serum vitamin E levels and nasal symptoms scores. In a controlled study, 112 patients with seasonal AR had lower nasal symptoms scores after high-dose vitamin E supplementation (800 IU/d) during the hay fever season . In contrast, another study showed that no significant effect on nasal symptoms in 63 patients with perennial AR after normal-dose vitamin E supplementation (400 IU/d) . The differences may be due to the subjectivity of the symptoms score and the fact that it is targeted at children; a larger sample and further clinical studies are needed to evaluate this relationship.