ORIGINAL ARTICLE LOWER AIRWAYS Influence of Mediterranean diet on asthma in children: A systematic review and meta-analysis L. Garcia-Marcos 1 , J. A. Castro-Rodriguez 2 , G. Weinmayr 3 , D. B. Panagiotakos 4 , K. N. Priftis 5 & G. Nagel 3 1 Pediatric Respiratory and Allergy Units, ‘Virgen de la Arrixaca’ University Children’s Hospital, University of Murcia, Murcia, Spain; 2 School of Medicine, Pontificia Universidad Catolica of Chile, Santiago, Chile; 3 Institute of Epidemiology and Medical Biometry, Ulm University, Ulm, Germany; 4 Department of Nutrition and Dietetics, Harokopio University in Athens, Athens, Greece; 5 Third Department of Pediatrics, Attikon Hospital, University of Athens Medical School, Athens, Greece To cite this article: Garcia-Marcos L, Castro-Rodriguez JA, Weinmayr G, Panagiotakos DB, Priftis KN, Nagel G. Influence of Mediterranean diet on asthma in children: A systematic review and meta-analysis. Pediatr Allergy Immunol 2013: 24: 330–338. Keywords asthma; Mediterranean diet; meta-analysis; wheeze Correspondence Prof. Luis Garcia-Marcos, Pabell  on Docente Universitario, Campus Ciencias de la Salud, Ctra. Madrid-Cartagena, s/n. 30120 El Palmar, Murcia, Spain. Tel.: +34868888129 Fax: +34868888127 E-mail: lgmarcos@um.es Accepted for publication 20 February 2013 DOI:10.1111/pai.12071 Abstract Background: There is epidemiological evidence that Mediterranean diet exposure is associated with lower asthma prevalence in children. We aimed to summarize the available data and to know whether the Mediterranean 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 Mediterranean 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 Mediterranean setting (centers <100 Km from the Mediterranean 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 Mediterranean diet score (OR 0.85, 95% CI 0.75–0.98; p = 0.02), driven by Mediterranean centers (0.79, 0.66–0.94, p = 0.009), although the difference with the non-Mediterranean 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 (Mediterranean); and 0.99, 0.79–1.25, p = 0.95 (non- Mediterranean); 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 (Mediterranean); 0.86, 0.75–0.98; p = 0.027 (non-Mediterranean); with the difference between regions being negligible. Conclusions: Adherence to the Mediterranean 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 Mediterranean populations. Asthma prevalence has increased dramatically over the past few decades with the highest incidence occurring in children (1). One of the potential environmental explanations of that increase relates to changes in diet (2). Modern diet is dominated by food which has been processed, modified, stored, and transported over great distances. Moreover, in the last decades, it has been a trend to consume higher amounts of sugar and saturated fats (e.g., burgers and soft drinks) (3). In contrast, traditional diet is produced and marketed locally and is eaten shortly after harvesting (4). The term ‘Mediterranean diet’ refers to dietary patterns found in olive-growing areas of the Mediterranean region, which is low in saturated fatty acids; rich in carbohydrates, fiber, and antioxidants; and has a high content of monounsaturated fatty acids and n-3 polyunsatu- rated fatty acids (PUFA), which are primarily derived from olive oil, and in some regions from fish (5). Some epidemiological studies reported a protective effect of adherence to Mediterranean diet on asthma in children/ adolescents; however, others did not or they could not conclude anything definitive (6–12). These contradictory find- ings might be due to the use of different Mediterranean indexes, diverse asthma outcomes, dissimilar populations of 330 Pediatric Allergy and Immunology 24 (2013) 330–338 ª 2013 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd Pediatric Allergy and Immunology