The role of selenium, zinc and antioxidant vitamin supplementation in the treatment of bronchial asthma: adjuvant therapy or not?

In the last few years, nutrition has represented an important conditioning factor of many cardiovascular, gastrointestinal and pulmonary chronic diseases. Many published works have documented specific inflammatory abnormalities in the airways of subjects with mild-to-moderate persistent bronchial asthma in which the inflammation state is often associated with an increased generation of reactive oxygen species and free radical-mediated reactions. This evidence has stimulated many researchers to suppose that the oxidative stress could be an important pathogenetic determining factor in the progression of chronic diseases, and the decrease of oxidant insults to the lung can be modified with antioxidant supplementary therapy. There are many studies regarding dietary interventions that confirm the relationship to oxidative stress, bronchial inflammation, the development of asthmatic symptoms and the lowered cellular reducing capacity. Simple dietary and environmental supplementations significantly reduce the oxidant stress, minimise the development of asthmatic symptoms, and should prove to be an effective new approach to asthma management in addition to current pharmacological strategies. Many randomised controlled trials with antioxidant vitamins and trace element supplements have not confirmed the results shown in other clinical trials. The aim of this review is to focus the attention on published works discussing the relationship between asthma and nutritional supplements (some trace elements and vitamins) and the effectiveness of these supplements in the treatment of bronchial asthma.