Prebiotic effect during the first year of life in healthy infants fed formula containing GOS as the only prebiotic: a multicentre, randomised, double-blind and placebo-controlled trial

Purpose Currently, there is no consensus concerning the possible beneficial colonic and systemic effects of prebiotic-containing infant formula. This study assesses whether the feeding of a galactooligosaccharides (GOS)-containing infant formula (0.44 g/dl of GOS) and the subsequent feeding of a GOS-containing follow-on formula (0.50 g/dl of GOS) have a prebiotic effect on intestinal microbiota that helps to decrease infections and allergy manifestations in healthy infants during the first year of life. Methods A multicentre, randomised, double-blind and placebo-controlled trial was carried out on 365 healthy term infants enrolled before 8 weeks of age and randomly assigned to a formula with or without GOS, until 12 months of age. The incidence of infections and allergy manifestations, the antibiotics prescribed and faecal characteristics were recorded up to 12 months of age, while faecal samples were collected up to 4 months for the measurement of secretory immunoglobulin A, short-chain fatty acids and microbiota. Results A prebiotic effect on the faecal analysis was observed at 4 months of life. The GOS group showed a lower faecal pH (P = 0.019), a lower decreasing trend in secretory immunoglobulin A (P = 0.078), lower butyric acid concentration (P = 0.040) and an increase in Bifidobacterium counts (P = 0.010). Changes in faecal characteristics involved greater frequency (P < 0.001) and softer consistency (P < 0.05). The incidence of infections or allergic manifestations during the first year of life was similar in both groups, with no statistical differences (P > 0.05). Conclusions The feeding of GOS-containing infant formula produced a definite prebiotic effect consisting of changes in faecal composition and microbiota, and in faecal consistency and the frequency of defaecation. No changes in the incidence of infection or allergic manifestation during the first year of life were observed.