Probiotics for prevention and treatment of respiratory tract infections in children: A systematic review and meta-analysis of randomized controlled trials

Abstract

Background: Respiratory tract infections (RTIs) represent one of the main health problems in children. Probiotics are viable bacteria that colonize the intestine and affect the host intestinal microbial balance. Accumulating evidence suggests that probiotic consumption may decrease the incidence of or modify RTIs. The authors systematically reviewed data from randomized controlled trials (RCTs) to investigate the effect of probiotic consumption on RTIs in children.

Methods: MEDLINE/PubMed, Embase, Cochrane Library, and Web of Science were systematically searched for RCTs regarding the effect of probiotics on RTIs in children. The outcomes included number of children experienced with at least 1 RTI episode, duration of illness episodes, days of illness per subject, and school/day care absenteeism due to infection. A random-effects model was used to calculate pooled relative risks, or mean difference (MD) with the corresponding 95% confidence interval (CI).

Results: A total of 23 trials involving 6269 children were eligible for inclusion in the systematic review. None of the trials showed a high risk of bias. The quality of the evidence of outcomes was moderate. The age range of subjects was from newborn to 18 years. The results of meta-analysis showed that probiotic consumption significantly decreased the number of subjects having at least 1 RTI episode (17 RCTs, 4513 children, relative risk 0.89, 95% CI 0.82-0.96, P = 0.004). Children supplemented with probiotics had fewer numbers of days of RTIs per person compared with children who had taken a placebo (6 RCTs, 2067 children, MD -0.16, 95% CI -0.29 to 0.02, P = 0.03), and had fewer numbers of days absent from day care/school (8 RCTs, 1499 children, MD -0.94, 95% CI -1.72 to -0.15, P = 0.02). However, there was no statistically significant difference of illness episode duration between probiotic intervention group and placebo group (9 RCTs, 2817 children, MD -0.60, 95% CI -1.49 to 0.30, P = 0.19).

Conclusion: Based on the available data and taking into account the safety profile of RCTs, probiotic consumption appears to be a feasible way to decrease the incidence of RTIs in children.

Figure 1

Selection process for the studies included in the meta-analysis.

Figure 2

Effect of probiotics on the number of subjects who had at least 1 RTI episode. The “total” is the number of subjects included in the analysis in probiotics and placebo group. CI = confidence interval, M-H = mantel-haenszel, RTI = respiratory tract infection.

Figure 3

Effect of probiotic on the duration of RTI illness episodes. The “total” is the overall number of illness episodes experienced by the participants,^[33,41,43] the number of participants with at least 1 illness episode,^{[36,38,39,44,49]} or the number of participants included in the analysis.^[55] CI = confidence interval, RTI = respiratory tract infection, SD = standard deviation.

Figure 4

Effect of probiotic on the number of days of RTI illness. The “total” is the number of participants with at least 1 illness episode,^[37,38,43] or the number of participants included in the analysis.^[45,55] CI = confidence interval, RTI = respiratory tract infection, SD = standard deviation.

Figure 5

Effect of probiotic on the days absent from day care/school. The “total” is the number of participants with at least 1 illness episode,^{[34,36,37,39,43]} or the number of participants included in the analysis.^[33,45,55] CI = confidence interval, SD = standard deviation.