Effects of Lactobacillus rhamnosus HN001 on acute respiratory infections and intestinal secretory IgA in children

Acute respiratory infections (ARI) are one of the main health problems in children, particularly in those under 5 years of age. The aim of this study was to evaluate whether the regular intake of the probiotic Lactobacillus rhamnosus HN001 affects the frequency, severity or duration of ARI in children attending day care centers during the winter season. A double-blind, placebo-controlled trial was carried out in 398 children (1 to 5 years old) who were randomized into two groups to receive daily for 3 months either 100 mL of a product containing HN001 (10 10 bacteria/day) or a control without the probiotic. ARI episodes and symptoms, absenteeism and antibiotic administration were registered. In a sub-group of children, oropharyngeal and fecal samples were obtained to detect pathogens, total Lactobacillus counts and secretory IgA, respectively. When comparing groups, neither the number nor the duration of the ARI, nor the days of absenteeism or antibiotic administration were statistically different. No differences between the groups in the detection rates of Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus pyogenes in the oropharyngeal samples were observed along the study. Fecal Lactobacillus counts as well as sIgA levels increased significantly during the study in the HN001 group, compared to the control ( P = 0.027 and P = 0.048, respectively). In the conditions in which this study was carried out, the regular intake of L. rhamnosus HN001 modulated the intestinal immune responses without affecting the frequency or severity of ARI in children.