Live probiotic microorganisms and oligosaccharides linked to prebiotics (in combination called symbiotics) are now increasingly used in children, especially under 2 years of age, but the evidence for long-term safety is still insufficient, although let it be known that probiotics and prebiotics have a modulating effect on the immune response.

A randomized, double-blind, placebo-controlled study was conducted to determine the safety and long-term effects of using prescribed antibiotics in the first 6 months of life.

Between November 2000 and March 2003, pregnant women were included in the study, whose children were at high risk for allergic reactions. All participants were randomized to receive either a mixture of 4 probiotics (Lactobacillus rhamnosus GG and LC705, Bifidobacterium breve Bb99 and Propionibacterium freudenreichii ssp shermanii) or a placebo for 4 weeks before delivery. For 6 months after delivery, the same probiotics were administered to children with 0.8 g of galactooligosaccharides or a placebo per day.

Follow-up visits were carried out at 3, 6 and 24 months of age and included a clinical examination and a survey of the parents to identify the child's safety information and physical development data. A full two-year follow-up period was conducted with 925 of the 1,018 children likely to be assessed.

In both study groups, children's physical development was normal, there were no intergroup differences in the incidence of children during the neonatal period, the incidence of intestinal colic during infancy and others characteristics of behavioral reactions associated with nutrition, and there were no differences in serious adverse events. During the 6 months of study intervention, antibiotics were prescribed less frequently in the symbiotic group compared to placebo (23% vs 28%). During the follow-up period, respiratory tract infections were less likely to occur in the antibiotic group compared to placebo (an average of 3.7 vs 4.2 episodes of infection).

According to the researchers, adding symbiotics to the normal diet of infants is safe and, apparently, increases children's resistance to respiratory infections in the first 2 years of life. Further studies in patients are needed to establish the immunological mechanisms by which symbiotics have such an effect.