The addition of a mixture of galacto-oligosaccharides (GOS) and fructo-oligosaccharides (FOS) to infant formula modifies the intestinal microbiota of infants, increasing the number of Bifidobacteria. However, it is not known whether this change has any clinical relevance. Because probiotics may have a preventive anti-infectious effect, we tested the hypothesis that prebiotics reduce the incidence of intestinal and respiratory infections in healthy young infants.
A prospective, randomised, placebo-controlled, 12 month open trial, was performed. Healthy infants, (15 to 120 days) were randomised either to a standard formula containing GOS/FOS in a 9/1 ratio, or to a control standard formula. At enrolment and after 3, 6, 9 and 12 months the following parameters were registered: anthropometric measures, number of episodes of acute diarrhoea and of respiratory tract infections.
281 infants completed the study, 136 in the GOS/FOS group and 145 in the control group. No differences in age, weight and length were observed between the groups at the enrolment. A reduced incidence of acute diarrhoea was observed in children on GOS/FOS compared to controls (0.15±0.03 vs. 0.28±0.04 episodes/child/12 months; p < 0.01). The number of children with at least one episodes of acute diarrhoea was significantly lower in the group of infants on GOS/FOS (17 vs. 34; p <0.05). The latter also showed a slight reduction of upper respiratory tract infections (URTI). Interestingly the number of children with more than 3 episodes of URTI/year was significantly lower in the group of children receiving GOS/FOS (19 vs. 35; p < 0.05).In addition the number of children who received more than two antibiotics courses/year was significantly lower in children on GOS/FOS (30 vs. 49; p< 0.05).
This is the first direct evidence that prebiotics reduce intestinal and possibly extra-intestinal infections and have therefore a clinical effect. These effects are probably due to the immune imprinting that follows microbiological imprinting in the first weeks of age.