« Update on Diet and Asthma »
Asthma is a common chronic disease, affecting 1 in 20 people in the world. Asthma was ranked in the recent Global Burden of Disease as the 28th cause of disability-adjusted life years. Asthma is considered to be due to a complicated interplay of genetic and environmental factors.
A frequently-cited possible cause of the asthma epidemic is changes in diet, particularly decreased consumption of fresh fruit and vegetables, and increased consumption of “Western” processed foods. Evidence supporting an etiologic role of diet comes mostly from studies of childhood asthma; diet appears to have little role in the etiology of adult-onset asthma. However, published studies on diet and asthma are very heterogeneous with regard to study design, assessment of the dietary exposure, and assessment of asthma itself, which has several different phenotypes.
Three recent studies provide additional evidence for a potential role of diet on asthma. In a large international study of children and adolescents (Ellwood et al.), fast food consumption was positively associated with the symptom prevalence of asthma and severe asthma, whereas a negative association was reported for fruit and vegetable intakes. In another study, Protudjer et al. shows that high vegetable intake was negatively associated with allergic asthma and with moderate-to-severe airway hyperresponsiveness. Regarding the role of diet as a disease modifi er, a randomized controlled trial conducted by Wood et al. concluded that among adults with asthma, increasing dietary antioxidants intakes by a food approach (i.e. increasing the consumption of fruits and vegetables) was associated with clinical asthma improvement, whereas no effect was reported for the supplement approach. Taken together, these studies support the promotion of a diet with high intake of fruit and vegetables, and low intake of fast foods, as a possible method to prevent the development of asthma in children, and improve asthma control in adults with asthma.