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Only a few reports have compared the fermentation of pectin and cellulose using the hydrogen-breath test, and no studies have examined the relation between the hydrogen breathing pattern and colonic microflora. Using breath-hydrogen measurements, we investigated whether different dietary fibers (DFs) were fermented differently and whether there were individual differences after ingestion of the same DF; we also examined the relation between individual fecal microflora and the fermentation of DF. Results of hydrogen tests in 14 men were compared after they had ingested 20 g of pectin, 20 g of cellulose, or 6 g of lactulose (a DF-like substance). We examined the relation between the breath hydrogen results and the subjects' fecal microflora. We defined significant fermentation (i.e., positive cases) as a continuous rise in hydrogen in the expiratory air of >19 ppm. The subjects were divided into 3 groups according to their hydrogen breath test pattern, i.e., positive for lactulose and pectin (Group LP, n = 4); positive for lactulose alone (Group L, n = 7); and negative for pectin, cellulose, and lactulose (Group N, n = 3). Individual differences were noted in subjects from Group LP and Group L. The detection frequency of lecithinase-negative clostridia was higher in Group LP than in the other groups (P < 0.05), and the detection frequency and the number of lecithinase-positive clostridia were higher in Groups LP and L than in Group N (P < 0.05). These findings suggest that the Clostridium species are associated with hydrogen production. The hydrogen breath test results of DFs depend on both the type of DF and the individual colonic microflora. The amount and constitution of colonic microflora might be predicted by the hydrogen-breath test using different DFs. J. Nutr. 134: 1881-1886, 2004. KEY WORDS: * pectin * cellulose * lactulose * microflora * Clostridium species

We developed a method which we used in the current study to observe the rat colon endoscopically. Our goal was to evaluate the entire course in the development of experimental large bowel tumors through serial observations in the same rat. We compared the effects of dietary lard and cellulose on rat colon tumorigenesis in a 2 x 3 factorial design. Sprague-Dawley rats (n = 90) were divided into 6 diet groups: rats were fed a diet without cellulose that contained 5, 10, and 15 g/100 g lard, or diets containing 15% cellulose diet (15 g cellulose/100 g diet) and the same concentrations of lard. The development of large bowel tumors induced by the administration of 1,2-dimethylhydrazine (25 mg/kg body weight) for 19 wk was examined endoscopically. Tumor induction rates in the 15% cellulose groups were lower than in the 0% cellulose groups (P = 0.008), independent of the lard concentration. These results suggest that the preventive effect of cellulose against large bowel tumorigenesis is greater than the promotive effect of fat under the current experimental conditions. J. Nutr. 134: 935-939, 2004. KEY WORDS: * dietary fiber * cellulose * fat * lard * large bowel tumorigenesis

According to the definition of resistant starch (RS), the true value of foodstuff-derived RS can be assessed only from that found in the contents of the terminal ileum. To date, a few methods exist for in viva measurement of RS in the terminal ileum, but their accuracy is questionable. The aim of this study was to quantify the level of RS in the terminal ileum to determine its true value as dietary fiber (DF). Volunteers (n = 7 men) were given a test meal containing 10 g of heat moisture-treated high amylose cornstarch (HMT-HAS) containing 8.8 g of RS as measured by Englyst's method. A double-lumen tube was positioned in the terminal ileum using the endoscopic retrograde bowel insertion method (ERBI). Intestinal contents were aspirated, and the amount of RS was measured as the glucose concentration (Englyst's method), and compared with the values for RS administrated orally using the same method. The mean amount of HMT-HAS-derived RS collected in the terminal ileum was 3.37 [+ or -] 0.95 g (mean [+ or -] SD), which was 34.5 [+ or -] 9.7% of the in vitro RS value. Furthermore, there were large individual differences in recoveries, ranging from 22.2 to 47.5%. The measured amount of HMT-HAS-derived RS was much smaller in our in vivo study than that measured in vitro, suggesting that in vitro measurement may inaccurately estimate the RS and DF levels of foodstuffs. The problem is further compounded by the large individual in viva variations in RS values from subjects consuming identical diets. KEY WORDS: * resistant starch * heat moisture-treated high amylose cornstarch * dietary fiber * absorption * endoscopic retrograde bowel insertion method

Abstract Background Since Fuchs' report in 1999, the reported protective effect of dietary fiber from colorectal carcinogenesis has led many researchers to question its real benefit. The aim of this study is to evaluate the association between diet, especially dietary fiber and fat and colorectal cancer in Japan. Methods A multiple regression analysis (using the stepwise variable selection method) was performed using the standardized mortality ratios (SMRs) of colon and rectal cancer in 23 Japanese prefectures as objective variables and dietary fiber, nutrients and food groups as explanatory variables. Results As for colon cancer, the standardized partial correlation coefficients were positively significant for fat (1,13, P = 0.000), seaweeds (0.41, P = 0.026) and beans (0.45, P = 0.017) and were negatively significant for vitamin A (-0.63, P = 0.003), vitamin C (-0.42, P = 0.019) and yellow-green vegetables (-0.37, P = 0.046). For rectal cancer, the standardized partial correlation coefficient in fat (0.60, P = 0.002) was positively significant. Dietary fiber was not found to have a significant relationship with either colon or rectal cancers. Conclusions This study failed to show any protective effect of dietary fiber in subjects with a low fat intake (Japanese) in this analysis, which supports Fuchs' findings in subjects with a high fat intake (US Americans).