Prebiotics (e.g. FOS) are ingredients promoting the propagation of probiotics. In other words, they are considered food for probiotic bacteria. Prebiotics are often non-digestible complex carbohydrates, found in different types of plants, vegetables and grains. These carbohydrates resist digestion by salivary and intestinal enzymes in the stomach and enter the intestines where they are fermented by probiotic bacteria. The most beneficial effect of fructooligosaccharides (FOS) is the selective stimulation of the growth of probiotic bacteria, thus significantly enhancing the composition of the intestinal microflora and reducing the number of potentially pathogenic bacteria.