The Effects of Prebiotics on Gut Bacterial Parameters, Immune Function & Exercise-Induced Airway Inflammation.

The current study will investigate the effects of prebiotic supplementation on airway inflammation/bronchoconstriction in adults diagnosed with Asthma/Exercise-Induced Bronchoconstriction (A/EIB). Previous research conducted in adults diagnosed with A/EIB has reported significant improvements in pulmonary function following three weeks of prebiotic supplementation. The significant improvements in pulmonary function were attributed to an attenuation of various markers of airway inflammation, potentially regulated by gut microbiota mediated improvements in systemic immune function. Prebiotics are a type of non-digestible carbohydrate/dietary fibre that can only be digested by certain beneficial bacteria. During the fermentation of prebiotics, beneficial bacteria produce energy/metabolites that can be used to support a variety of human immune functions, such as reducing the level of airway inflammation that occurs following exposure to relevant triggers (e.g. exercise). Imbalances and/or deficiencies in gut bacterial composition/metabolic activity have been identified in children/adults diagnosed asthma. However, the potential mechanisms behind prebiotic mediated improvements in the severity of asthma have yet to be investigated. Participants with and without A/EIB will be allocated two separate nutritional supplements following a double-blind, placebo-controlled design. During the first phase of the nutritional intervention, participants will consume the first supplement (either prebiotic or placebo), for a total duration of four weeks. A two-week wash out period will then be completed before the remaining nutritional supplement is administered for an equal duration. Analyses of key human/bacterial metabolite concentrations will be carried out alongside assessments of immune and pulmonary function, and intestinal permeability at baseline, and throughout all phases of the nutritional intervention. Current understandings of the role of the gut microbiota in the pathogenesis of A/EIB will be expanded through the investigation of novel pathophysiological mechanisms, helping to inform future therapeutic prospects for asthma.