Non-digestible and/or non-absorbable saccharides, such as non-digestible oligosaccharides, non-digestible sugar alcohols and dietary fiber, are not hydrolyzed by human intestinal enzymes, and they are utilized through fermentation by intestinal microbes. They have much physiological function and supplemental value for human health and are widely used as ingredients in medicine and processed food. In order to clarify their bioavailability in healthy humans, my colleague and I have accumulated some data based on the following human studies: I) evaluation of the available energy from non-digestible and/or non-absorbable saccharides and estimation of the maximum permissive dose of non-digestible oligosaccharides and non-digestible sugar alcohols that does not induce osmotic diarrhea; and II) stimulation of evacuation and suppression of diarrhea by oral ingestion of non-digestible oligosaccharides, and soluble and insoluble dietary fibers. We believe that these data obtained from human studies could contribute to the promotion of human health and the prevention for diarrheal diseases.

Key words: non-digestible and/or non-absorbable saccharide, dietary fiber, available energy, diarrhea, osmotic diarrhea, prebiotics