Studies of oligosaccharides have recently become common, especially in Japan. This has been because of findings of marked biofunctions and usefulness of fructooligosaccharides (FOS) for human health due to their effect of improving the intestinal microflora. In this paper, we demonstrate several useful characteristics of FOS such as cholesterol reduction, suppression of putrefaction, normalization of microbial disorders of the colon and alleviation of constipation in clinical studies. It seems that the usefulness of FOS is related to the proliferation of bifidobacteria and other saccharolytic intestinal bacteria and also short chain fatty acids produced by these organisms .

Fructo-oligosaccharides are widely distributed in plants such as onions, asparagus, wheat etc., and obtained from sucrose by the action of fructosyltransferase. They are not hydrolyzed by human digestive enzymes, but are utilized by intestinal bacteria such as bifidobacteria. Bacteroides fragilis group, peptostreptococci and klebsiellae. In the experiment with 23 patients (73 +/- 9 years old), improvement of fecal microflora was observed by oral administration of fructo-oligosaccharides 8 g per day for two weeks: the population of bifidobacteria in feces increased about 10 times compared before the administration; average pH of stool showed 0.3 lower than that before administration.

A study was made of the effects of fructooligosaccharides, which exist widely inplants such as onion, edible burdock, wheat etc., on the human and animal intestinal flora. Fructooligosaccharides are produced from sucrose with the aid of β-fructofuranosidase from Aspergillus niger on a commercial scale by Meiji Seika Kaisha, Ltd.(Neosugar, Meioligo®). It has been found that they are not hydrolyzed by any digestive enzymes of humans and animals. Moreover utilization byvarious kinds ofintestinal bacteria indicated that Bifidobacterium spp., the Bacteroides fragilis group, Peptostreptococcus spp. and Klebsiella pneumoniae can utilize these saccharides, but Clostridium perfringens, Escherichia coli and others cannot. The fructooligosaccharides are selectively utilized, particularly by bifidobacteria.The clinical studies showed that fructooligosaccharides administration improved the intestinal flora, with subsequent relief of constipation, improved blood lipids in hyperlipidemia, and suppressed the production of intestinal putrefactivesubstances.