Oligosaccharides are known to be a low-energy sweetener offering the same degree of sweetness as sugar. In fact, they are equipped with a diverse array of functions, one of which is regulating the condition of the gut by serving as food for beneficial gut bacteria such as Lactobacillus and Bifidobacterium. However, recent studies have shown that not only “good” bacteria, but also other gut bacteria can feed off them. Accordingly, attention has turned to oligosaccharides that promote the proliferation of beneficial bacteria alone, and development efforts in this area are progressing. Scientists say that in the future, it will be possible to use oligosaccharides to create next-generation prebiotics readily capable of improving the gut microbiota.