You can find information on this in various websites. Just do a search on google on "bifidogenic effects".

For example, here's some relative info I found:
Fructofibres have a bifidogenic effect. They promote the proliferation of the beneficial bifidobacteria and encourage their metabolic selectivity. A healthy intestinal flora is not only important for our wellbeing, but also improves the absorption of nutrients, accelerates transit and strengthens the immune system’s defences.