Relationships between analytical methods and the definition of dietary fiber are reviewed with analytical history, and discussed on the basis of results of the authors and their colleagues.1) The review discussed on protein-nitrogen and none protein-nitrogen which reduced as an undigestible material through Prosky method. Therefore, a modified determination method including an undigestible material after enzyme hydrolysis, was proposed in this review.2) The analytical process for Van Soest, Southgate, Asp, Prosky, modified Prosky, Englyst and Upsala method respectively, discussed using each sample or as a model.3) Resistant starch (RS) was prepared with pancreatin amylase digestion completely, but it dissolved about 50 % by the digestion of Prosky method. Therefore, a new analytical method of RS may be necessary except Termamyl digestion.4) Relationship between enzymatic method and HPLC procedure for EtOH soluble DF were discussed.

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We examined the effects of indigestible dextrin(IDex) on both blood glucose and insulin responses to the various sugar loadings in the healthy subjects. Moreover, we conducted a study of the test-meal ingestion in order to evaluate the efficacy of Ibex on postprandial rise in blood glucose levels. The results are summarized as follows: 1) IDex reduced the rises in both plasma glucose and insulin levels after sucrose loading. Although IDex had no effect on rises in plasma glucose levels, insulin levels both after glucose and maltodextrin loadings were reduced by IDex. 2) The postprandial blood glucose level after ingestion of the test-meal-1 (Japanese noodle and rice: carbohydrate 104.2g and 565kcal) was rapidly increased, on the contrary that after the test-meal-2 (sweet roll: carbohydrate 137.2 g and 553kcal) was gradually increased. In ingestion of both the test-meals, IDex showed the remarkable reducing effect on rises in blood glucose levels.

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A randomized, double-blind trial was carried out in 24 voluntary young wemen to compare the hypocholes terolemic effect of 1g chitosan added rice gruel with that of placebo for 3weeks. All subjects except placebo group ingested 1g of chitosandaily in addition to their ordinary diets. The serum total cholesterol value reduced in high cholesterol group ( > 181mg/dl), but in low cholesterol group ( < 180mg/dl) such phenomenon was not observed. It is understood that chitosan has a control function associated with hypocholesterolemic effet only in high cholesterol subjects, and this substance is considered to be safe in its application to dietary therapy.

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The aim of this study is to evaluate the intake of dietary fiber based on four 4-week diet records. The subjects for this study are women who are resident in Fukuoka Prefecture. Valid diet records were obtained from 34 subjects. Daily intakes of total dietary fiber (TDF), soluble dietary fiber (SDF) and insoluble dietary fiber(IDF) were calculated from these diet records. In addition, proportion of DF intake from each food relative to total intake of DF was also computed to identify what foods contribute to total intake of DF Average daily intakes of TDF, SDF and IDF were 9.5 ± 4.9g, 1.6 ± 1.1g, 7.7 ± 3.8g, respectively. Average daily intake of TDF was lower than 10g. In TDF intake by foods, proportion of DF intake from rice showed 10.3 % relative to total intake of DF, which was the most contributed food. SDF intake from orange showed the highest proportion (9.3 %) relative to total intake of SDF. As in TDF intake, IDF intake from rice resulted in the most dominant one (12.7 % ). Proportions of intake from top fifty foods contributing to total intake of DF in TDF, SDF and IDF were 86.7 %, 89.9 % and 88.9 %, respectively. The cumulative proportions of foods contributing to intake of DF in TDF, SDF and IDF showed the plateau at about 100 foods. These results suggest that average daily intake of DF at a long-term diet record indicated the lower value than ever reported ones. This may occur because of differences in the methods for dietary assessment or areas of survey. Further study based on a long-term diet record is required to examine the intake of DF in daily life.

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The digestibility of oligosaccharides was studied by the modified Prosky method (Enzymatic-LC method), which was officially adopted the determination of low-molecular soluble dietary fiber. When the low-digestible saccharide, isomaltooligosaccharide (IMO) and its hydrogenated derivative (IMO-H) were applied to the methods, the hydrolysis ratios were relatively lower than those of starch hydrolysate, although the ratios depended on the concentrations of enzyme and substrate. Changes in saccharides composition of IMO or IMO-H were almost the same as those which were observed in our previous studies using intestinal mucosa enzyme. These results suggested that the Enzymatic-LC method could be useful for estimation of digestibility for some kinds of oligosaccharide, derived from starch. Further improvements of the enzymatic digestion system, which could simulate a human gastric enzyme mixture, will be able to establish an available method for various types of oligosaccharides.

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