Bioavailability and Laxative Threshold of 1-kestose in Human Adults

1-kestose is a trisaccharide and is one of the components of fructooligosaccharide (FOS). Although FOS is a typical non-digestible oligosaccharide with several beneficial health effects that have been clarified, the detailed properties of 1-kestose itself remain unknown. We first determined the digestibility of 1-kestose using rat and human small intestinal homogenates and the inhibition of 1-kestose to intestinal disaccharidases activity using rat small intestinal brush border membrane vesicles (BBMV). Thereafter, we estimated the bioavailability of 1-kestose based on the results from incremental blood glucose and insulin levels and breath hydrogen excretion after the oral ingestion of 5 and 30 g of 1-kestose in healthy human subjects. 1-kestose was hardly hydrolyzed by the rat and human intestinal disaccharidases, and competitively inhibited trehalase. When human subjects ingested 1-kestose, the blood glucose and insulin did not respond, and the excretion of breath hydrogen in a dose-dependent manner was markedly observed. The permissive dose for transitory diarrhea was estimated to be 0.24 g/kg of body weight in male subjects and 0.34 g/kg of body weight in female subjects. These results demonstrate that 1-kestose is a candidate to be the prebiotic agent in addition to FOS, and that the available energy of 1-kestose was estimated at 2 kcal/g based on the calculation method of the Health Promotion Act in Japan. _____________________________________________________________________________________________________________