Probiotics and vitamin C for the prevention of respiratory tract infections in children attending preschool: a randomised controlled pilot study

BACKGROUND: This pilot study investigates the efficacy of a probiotic consortium (Lab4) in combination with vitamin C on the prevention of respiratory tract infections in children attending preschool facilities. SUBJECTS/METHODS: In a double-blind, randomised, placebo-controlled pilot study with children aged 3-6 years, 57 received 1.25 x 10(10) colony-forming units of Lactobacillus acidophilus CUL21 (NCIMB 30156), Lactobacillus acidophilus CUL60 (NCIMB 30157), Bifidobacterium bifidum CUL20 (NCIMB 30153) and Bifidobacterium animalis subsp. lactis CUL34 (NCIMB 30172) plus 50 mg vitamin C or a placebo daily for 6 months. RESULTS: Significant reductions in the incidence rate of upper respiratory tract infection (URTI; 33%, P = 0.002), the number of days with URTI symptoms (mean difference: -21.0, 95% confidence interval (CI): -35.9, -6.0, P = 0.006) and the incidence rate of absence from preschool (30%, P = 0.007) were observed in the active group compared with the placebo. The number of days of use of antibiotics, painkillers, cough medicine or nasal sprays was lower in the active group and reached significance for use of cough medicine (mean difference: -6.6, 95% CI: -12.9, -0.3, P = 0.040). No significant differences were observed in the incidence rate ratio or duration of lower respiratory tract infection or in the levels of plasma cytokines, salivary immunoglobulin A or urinary metabolites. CONCLUSIONS: Supplementation with a probiotic/vitamin C combination may be beneficial in the prevention and management of URTIs.