Evaluation of the efficacy of Lactobacillus plantarum HEAL9 and Lactobacillus paracasei 8700:2 on aspects of common cold infections in children attending day care: a randomised, double-blind, placebo-controlled clinical study

Background The combination of Lactobacillus plantarum HEAL9 and Lactobacillus paracasei 8700:2 (commercially available as Probi Defendum ® ) has previously been reported to reduce the incidence, duration and severity of naturally acquired common colds in adults. The aim of the present study was to evaluate the impact of Probi Defendum ® on aspects of common cold in healthy children 1–6 years of age attending day care. Methods A total of 131 children, out of the planned 320, were recruited into the study during 1 common cold season and randomised to consume once daily either 10 9 CFU (colony forming units) of the probiotic product or placebo. Due to unforeseen reasons, the recruitment of more children did not continue beyond the first cold season. Results There were 106 children that completed the study out of the 131 randomised. Daily consumption of the probiotic product for a period of 3 months significantly reduced the severity of the symptom “nasal congestion/runny nose” with a mean severity score for the whole study period of 7.5 ± 9.7 in the probiotic group and 13.9 ± 15.2 in the placebo ( p < 0.05). Moreover, significantly less concomitant medication was used in the probiotic group. When the data were projected to a larger population corresponding to the originally estimated sample size, the results were in favour of the probiotic group regarding the reduced absence from day care ( p < 0.05), reduced mean total severity per day in the reported episodes ( p < 0.05) and reduced severity of the symptom “crying more than usual” ( p < 0.05). Conclusion Intake of Probi Defendum ® once daily for a period of 3 months was beneficial to children and reduced the severity of common colds.