Objective Probiotics are live microorganisms, which when administered in sufficient amounts may improve health. Although many products are recommended by physicians few commercially available products have strong clinical evidence. The study had two primary outcomes, common infectious diseases and change of behaviour due to illness as assessed by parents.
Methods Double-blinded randomised placebo controlled allocation concealment clinical trial. Outpatient participants in the Washington, DC, metropolitan area. Healthy children between the age of 3 and 6 years attending daycare/school centres 5 days a week. The intervention was a modification of DanActive, a probiotic dairy drink. The active probiotic is Lactobacillus casei. Placebo was a matching strawberry-flavoured dairy drink. Common infectious diseases were subdivided by the three types or classifications: upper respiratory tract infections (URTI); lower respiratory tract infections (LRTI); gastrointestinal tract infections (GITI). Parents were asked if due to illness their child had a change in daily activity.
Results The incidence rate for common infectious diseases in the active group was 0.0782 compared with 0.0986 in the placebo, representing a statistically significant 19% decrease in the active group (incidence rate ratio (IRR) 0.81, 95% CI 0.65 to 0.99, p = 0.013). The IRR for GITI is 24% lower in the active group compared with the control group (IRR 0.76, 95% CI 0.58 to 0.99) and for URTI 18% lower (IRR 0.82, 95% CI 0.68 to 0.99). The other primary outcome, rate of days with change in activity due to illness, was not significant.
Conclusions DanActive appears effective in reducing overall illness, specifically GITI and URTI.