GOS is a prebiotic. The main similarity between pre- and probiotics is that they both result in beneficial effects to the host after consumption. Combinations of pre- and probiotics with synergistic effects are often referred to as synbiotics. Clinical studies with infants and children indicated that addition of galacto-oligosaccharides to a probiotic mixture resulted in higher numbers of Bifidobacteria and increased resistance to respiratory infections during the first two years of life as compared to only the probiotic.