Combiotic formula is the term used by Hipp baby formula that includes prebiotics for digestive health. Prebiotics are naturally found in breastmilk to support a baby's gut.
Along with the good fats, proteins, and carbohydrates that your baby needs, it also has the vitamins and minerals that are important in all baby formulas. The difference is the prebiotic fibers called galacto-oligosaccharides (GOS). This comes from lactose.
If you are comparing the origins of the packages, there is a slight variation. All Hipp Combiotic formulas contain the GOS. The German version has the addition of L. Fermentum, which is the probiotic that is also found in breastmilk. This combination of a prebiotic and a probiotic is called symbiotic in which they work together to aid your baby's gut health. Another difference is that the Dutch and British versions are starch free while the German versions do contain starch from corn.
Parents who switch between traditional formula and combiotic formula can tell you first-hand about their experience. For a more scientific answer, there is an active clinical study sponsored by Hipp posted on the National Institutes of Health (NIH) site, a division of the U.S. Department of Health and Human Services. The study's objective is to demonstrate how a combiotic formula with both a prebiotic and probiotic can reduce the incidence rate of episodes of infectious diarrhea. It started in 2014, however the study is not scheduled to be complete until September of 2020.