Effect of diet on Asthma and Allergic sensitization in Phase Two International Study on Allergies and Asthma in Childhood (ISAAC)

Background: We assessed the association between dietary factors, asthma and allergy in a large international study including objective measurements of atopy. Methods: Between 1995 and 2005 cross-sectional studies were performed in 29 centers in 20 countries. Parental questionnaires were used to collect information on allergic diseases and exposure factors. We analyzed data from 49,936 randomly selected schoolchildren (8–12 years, 31,759 with skin prick testing). Random effect models for meta-analysis were applied to calculate combined odds ratios. Results: Fruit intake was associated with low prevalence of current wheeze in affluent (ORadj, 0.86; 95% CI, 0.73–1.02) and non-affluent countries (ORadj, 0.71; 95% CI, 0.57–0.88). Consumption of fish in affluent countries (ORadj, 0.85; 95% CI, 0.74–0.97) and of cooked green vegetable in non-affluent countries (ORadj, 0.78; 95% CI, 0.65–0.95) was associated with lower prevalence of current wheeze. Overall, more frequent consumption of fruit, vegetables and fish was associated with lower lifetime prevalence of asthma, whereas high burger consumption was associated with higher lifetime asthma prevalence. None of the food items was associated with allergic sensitization. Except for fruit juice and fruit consumption no associations with atopic wheeze were found. Food selection according to the „Mediterranean diet“ was associated with lower prevalence of current wheeze and asthma ever (ptrend 0.03). Conclusion: Our observations support previous reports that the adherence to a „Mediterranean diet“ may provide protection against wheeze and asthma in childhood. As consumption of fish, fruit and vegetables are widely recommended for prevention of cardiovascular disease and cancer; our findings suggest that these public health initiatives are unlikely to be harmful in relation to childhood asthma symptoms. However, the causal significance of this observation has to be confirmed in prospective studies and experimental trials.