A Comparative Interrupted Times Series on the Health Impact of Probiotic Yogurt Consumption Among School Children From Three to Six Years Old in Southwest Uganda

Introduction: Following a school milk feeding program in Southwest Uganda, we initiated a probiotic yogurt school feeding program in the same region in 2018. In order to investigate the potential health benefits from probiotic yogurt we conducted an observational study, where we compared the effect of the consumption of locally produced probiotic yogurt containing Lactobacillus rhamnosus yoba 2012 to milk in pre-primary schoolchildren from different schools on the occurrence of respiratory tract infections (common cold) and skin infections (e.g., tinea capitis). Method: A comparative interrupted time series over a period of 3 weeks of baseline followed by 9 weeks of 100 ml of probiotic yogurt or milk consumption for 5 days per week. In total 584 children attending five different schools were followed during consumption of probiotic yogurt and 532 children attending five other schools during consumption of milk. Incidences of respiratory tract infection symptoms and skin infection symptoms, changes in anthropometric indicators and absenteeism were recorded. Results: Over the course of the study period the incidence rate for common cold symptoms decreased faster in the yogurt group than in the milk group (p = 0.09) resulting in a final RR of 0.85 (95% CI: 0.5–1.4) at the end of the observational period. The incidence rate of skin infection related symptoms also reduced faster in the yogurt group compared to the milk group (p < 0.0001) resulting in a relative risk factor (RR) of 0.6 (CI: 0.4–0.9) at the end of the observational period. Anthropometric indicators and level of absenteeism did not show significant differences between yogurt and milk. Conclusion: Notwithstanding the observed positive trend and effect of probiotic yogurt on the incidences of common cold and skin infections, respectively, we consider the results of this comparative interrupted time series inconclusive due to differences in the recorded health parameters between the probiotic yogurt and milk control groups at base line, and fluctuations over the course of the intervention period. An improved study design, with more uniform study groups, a longer intervention period and a third control group without yogurt or milk is required to draw definitive conclusions.