AbstractObjectiveTo quantify the association between breast-feeding and Helicobacter pylori infection, among children and adolescents.DesignWe searched MEDLINE^TM and Scopus^TM up to January 2013. Summary relative risk estimates (RR) and 95 % confidence intervals were computed through the DerSimonian and Laird method. Heterogeneity was quantified using the I² statistic.SettingTwenty-seven countries/regions; four low-income, thirteen middle-income and ten high-income countries/regions.SubjectsStudies involving samples of children and adolescents, aged 0 to 19 years.ResultsWe identified thirty-eight eligible studies, which is nearly twice the number included in a previous meta-analysis on this topic. Fifteen studies compared ever v. never breast-fed subjects; the summary RR was 0·87 (95 % CI 0·57, 1·32; I²=34·4 %) in middle-income and 0·85 (95 % CI 0·54, 1·34; I²=79·1 %) in high-income settings. The effect of breast-feeding for ≥4–6 months was assessed in ten studies from middle-income (summary RR=0·66; 95 % CI 0·44, 0·98; I²=65·7 %) and two from high-income countries (summary RR=1·56; 95 % CI 0·57, 4·26; I²=68·3 %). Two studies assessed the effect of exclusive breast-feeding until 6 months (OR=0·91; 95 % CI 0·61, 1·34 and OR=1·71; 95 % CI 0·66, 4·47, respectively).ConclusionsOur results suggest a protective effect of breast-feeding in economically less developed settings. However, further research is needed, with a finer assessment of the exposure to breast-feeding and careful control for confounding, before definite conclusions can be reached.