Probiotics play no role in prevention of infections in infants
Daily administration of two probiotic strains, Bifidobacterium animalis subsp lactis and Lactobacillus rhamnosus, does not appear to be effective in the prevention of respiratory or gastrointestinal infections in infants, as shown in the ProbiComp* study.
In a cohort of infants aged 8 to 14 months (mean 10 months) who were randomized to receive either the probiotic combination (n=143) or placebo (n=142) for 6 months, the primary endpoint of the number of days absent from child care due to respiratory or gastrointestinal infections did not significantly differ between the two treatment arms (median absence, 11 days for both; mean difference, 1.14; p=0.19). [Pediatrics 2017;doi:10.1542/peds.2017-0735]
Likewise, there was no between-group difference observed in the following secondary endpoints: the number of children with doctor-diagnosed upper or lower respiratory tract infections, the number of doctor visits, antibiotic treatments, occurrence and duration of diarrhoea, and days with common cold symptoms, fever, vomiting, or caregivers’ absence from work.
Infants in the probiotic combination group were administered B animalis subsp lactis and L rhamnosus, each at a dose of 109 colony-forming units daily for 6 months. No adverse events related to the combination probiotics were reported.
Researchers noted that the power of the present study might have been reduced by a potential immunoprotective effect of breastfeeding, with breast milk shown to be an important factor in the developing immune system and in the protection against infections during infancy. [J Nutr 2005;135:1–4]
“The infants in our study were on average 10 months old at baseline, and 47.4 percent were still breastfeeding. The average age of termination of breastfeeding for these infants was 12.1 months,” researchers said.
“Another important consideration is that the infants were of generally good health, and the families were recruited after replying to an invitation. This resulted in a self-selected population of primarily well-educated, high-income families with a special interest in the study,” they added.
Taking the aforementioned factors into account, the results of the study cannot be readily extrapolated to children in other age groups or in different settings, researchers said.
In a companion paper, Dr Michael D. Cabana from the University of California and Dr Daniel J. Merenstein from the Georgetown University Medical Center highlighted that an intervention consisting of a probiotic supplement occurs in the context of many potential exposures that can influence the risk of childhood illness and child care attendance. [Pediatrics 2017;doi:10.1542/peds.2017-1729]
“Given the positive effects of breastfeeding in preventing common infections and the high percentage of infants who were breastfed, it may be difficult to discern the effects of a probiotic supplement in the [ProbiComp] study,” they wrote.
Aside from breast milk exposure, patient age may also factor in the effectiveness of a probiotic supplement in influencing the GI microbiota, Cabana and Merenstein added.
“Changes in diet, such as the cessation of breastfeeding and the introduction of ‘table foods,’ are associated with the evolution of the microbiome to a more ‘adult-like’ composition,” they said, referencing two previous trials reporting the success of a probiotic supplementation in decreasing the number of days absent in child care among children aged >4 years and between 8 and 13 months. [Clin Nutr 2010;29:312–316; Eur J Clin Nutr 2015;69:373–379]
Although leading to further questions, the current study indirectly provides “additional information on the relative value of a probiotic intervention compared with breastfeeding and diet, and perhaps another reason to encourage breastfeeding as long as possible,” said Cabana and Merenstein.
*Effect of Probiotics in Reducing Infections and Allergies in Young Children Starting Daycare