Dietary fiber would decrease mineral bioavailability because it may have cation exchange capacity, bind mineral ion and form complexes difficult to absorb in intestinal lumen, as phytin does. But in actually, many dietary fibers have already appeared to be a good source of minerals especially in mineral deficiency, even if some dietary fibers contained considerable amount of phytin. Moreover, some dietary fibers and other luminacoids, proposing term as dietary components which are not digested and/or absorbed in the human small intestine and which exert physiological effect that are useful in maintaining good health via gastrointestinal tract, appeared to improve mineral bioavailability.

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Sodium alginate preparation (average of m.w.>300, 000) was depolymerized by incubation with Vibrio alginolyticus SUN53 (NITS-P-1.4) isolated from marine bacteria in sandy beach of Nagasaki by Ueda. The lyophilized powder of depolymerized product of sodium alginate, of which molecular weight was approximately 1, 000, was obtained. The solution of the product inhibited the activities of sucrase, maltase, isomaltase, lactase, and trehalase using rat intestinal brush border membrane vesicles. By the addition of the depolymerized sodium alginate, sucrase and lactase, maltase, and isomaltase were inhibited approximately 60%, 35%, and 45%, respectively. These inhibitory effects depended on the concentration of the product. However, trehalase was not so clearly inhibited. These inhibitory modes were competitive by Lineweaver-Burk plot. These results suggest that the depolymelized sodium alginate by Vibrio alginolyticus SUN53 could contribute to develop the ingredient, which have the possibility of the suppressive effect of postprandial blood glucose levels.

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Six Wistar male rats (3wk) in each group were raised with the restricted feeding the diets containing 10% of lactulose(LAT), fructooligosaccharide(FOS), galactosylsucrose(GS) or isomaltooligosaccharide(IMO) instead of sucrose to give the equal quantity for 44 days. Blood lipid parameters, osmotic diarrhea, fecal hydrolase activity, and short-chain fatty acids(SCFAs) of cecal content were investigated. Final body weight and blood lipid parameters were not significantly different among 5 groups. LAT and FOS caused osmotic diarrhea, but GS and IMO didn't. Amount of total SCFAs were significantly higher in LAT and FOS than in control, GS and IMO. The activity of β-glucronidase and β-glucosidase were also significantly lower in LAT and FOS than control, GS and IMO. These results demonstrate that the beneficial health effects depend on the difference in digestibility, fermentability and utilization by intestinal microbiota among oligosaccharides.

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