Relationships between determination methods and definitions of dietary fiber were reviewed and discussed with history of analysis methods.1) The definition accepted at the Japanese Association for dietary fiber Research, the definition of AOAC-AACC and the definition established in Europe were introduced. There are items about a physiological function in these definitions of dietary fiber. However, it is only the item of digestibility that Enzymatic-Gravimetric Method deals with the definition. It is difficult to make the physiological function in an alimentary canal reflect in assay.2) Evaluation was carried out from the historical side of Established methods and Official methods of determination. It was discussed that what kind of DF which can be analyzed or cannot be analyzed as quantitative analysis on the basis of the feature of an analytic principle.3) Newly Method "A Simplified Modification Method of AOAC Official Method 991.43 (Enzymatic Digestion under Constant pH) (J.AOAC Int. 90, 217-237(2007))" which was authorized by Japanese Association for Dietary Fiber Research was introduced too.

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The present paper was attempted to examine the effect of a water-soluble dietary fiber (SDF) extracted from Opuntia Streptacantha (OpS) on postprandial blood glucose level. A OpS-SDF was extracted from the hot-dried OpS powder . An elevation of the postprandial blood glucose level in GK rats ( a Type II diabetes model animal ) given 0.2, 1 or 2% OpSSDF solution orally together with 20% glucose solution was significantly suppressed as compared with that observed in the control rats given only glucose solution. The diffusion rate of glucose and the permeation rate of glucose in the cultured CACO-2 cells were significantly reduced by the addition of OpS-SDF as compared to the control. Further, in the examination on the physico-chemical characteristics of OpS-SDF, we obtained that the glucose diffusion inhibition rates of the 0.2 or 0.5% OpS-SDF solution was markedly high compared with that of pure water. The viscosity of 2% OpS-SDF solution was found to be about 3, 000 times high compared with that of pure water. It was revealed that OpS-SDF in OpS is a kind of mucilaginous SDF and has the significant suppressing effect for elevation of postprandial blood glucose level.

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We evaluated the effects of a dessert beverage supplemented with indigestible dextrin (4.2 g of dietary fiber) on frequency and fecal characteristics in 38 healthy female students (age 19.8 ± 0.9 years). The subjects were divided into two groups for a crossover study. The study duration of 7 weeks was divided into 5 periods: non-intake period (I: one week, control period); intake period (II: two weeks, test period); non-intake period (III: one week, free period); intake period (IV: two weeks, test period); and non-intake period (V: one week, free period). A beverage containing no indigestible dextrin was used as a placebo. For the entire seven weeks, the subjects filled out daily questionnaires concerning their defecation and fecal conditions and weekly questionnaires concerning their health conditions. Subjects with slight constipation significantly increased their frequency of defecation, the number of days with defecation, and the amount of defecation during the test period when they received the beverage containing indigestible dextrin, as compared to the control period (n=12). Moreover, these subjects also significantly increased their number of days with defecation compared to those when consuming the placebo beverage. The health conditions questionnaire also showed an improvement in constipation when the subjects consumed the beverage containing indigestible dextrin.

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