Plant-derived foods for the attenuation of allergic airway inflammation

Asthma is an allergy-mediated inflammatory disease characterised by infiltration of the airway with mast cells, lymphocytes, and eosinophils. The disease is induced by co-ordination of T-helper cell type 2 (Th2) cytokines and inflammatory signal molecules. Fruits and vegetables are a rich source of polyphenolic bioactive compounds, which have been observed to have health-promoting properties when consumed by humans. In particular, fruit-derived proanthocyanins and anthocyanins have been found to attenuate lung inflammation. Epidemiological studies have revealed correlations between fruit consumption and a lower prevalence of respiratory symptoms and lower incidence of non-specific lung diseases. In this review we summarise the current understanding of the pathophysiologic mechanism(s) involved in the development of allergic airway disease. We also review evidence of the beneficial effects of plant-derived foods, their components and metabolites in allergic airway inflammation arising from in vitro and rodent studies, epidemiological studies and human intervention trials. The mechanism, biological relevance and functional benefits, such as immune modulation (e.g. reduction in cytokine and eotaxin production), antioxidant ability, tissue remodelling and tight junction function are also discussed.