Influence of M editerranean diet on asthma in children: A systematic review and meta‐analysis

Background There is epidemiological evidence that M editerranean diet exposure is associated with lower asthma prevalence in children. We aimed to summarize the available data and to know whether the M editerranean setting modifies this association. Methods The literature search, up to May 2012, was on epidemiological studies in the general population of children assessing whether adherence to M editerranean diet (measured as a score) was associated with the prevalence of ‘current wheeze’; ‘current severe wheeze’; or ‘asthma ever’. Odds ratios ( OR ) of the eight included studies compared the highest tertile of the score with the lowest. Random‐effects meta‐analyses for the whole group of studies and stratified by M editerranean setting (centers <100 Km from the M editerranean coast) were performed. Differences between strata were assessed using the Q test. Results For ‘current wheeze’, there was a negative significant association with the highest tertile of M editerranean diet score ( OR 0.85, 95% CI 0.75–0.98; p = 0.02), driven by M editerranean centers (0.79, 0.66–0.94, p = 0.009), although the difference with the non‐ M editerranean centers (0.91, 0.78–1.05, p = 0.18) was not significant. The results for ‘current severe wheeze’ were as follows: 0.82, 0.55–1.22, p = 0.330 (all); 0.66, 0.48–0.90, p = 0.008 ( M editerranean); and 0.99, 0.79–1.25, p = 0.95 (non‐ M editerranean); with the difference between regions being significant. For ‘asthma ever’, the associations were as follows: 0.86, 0.78–0.95, p = 0.004 (all); 0.86, 0.74–1.01, p = 0.06 ( M editerranean); 0.86, 0.75–0.98; p = 0.027 (non‐ M editerranean); with the difference between regions being negligible. Conclusions Adherence to the M editerranean diet tended to be associated with lower occurrence of the three respiratory outcomes. For current and current severe wheeze, the association was mainly driven by the results in M editerranean populations.