There has been increasing reports concerning relationship between starch intake and bowel health. According to recent evidences, resistant starch(RS), a fraction of starch that survive digestion in the small intestine and reach large bowel, plays major roles in the health-promoting action of starch. In this review, we will describe some important physiological effects of RS including its historical background, formation and existence in food and functions in the large intestine. RS increased fecal mass, fecal water-holding capacity and cecal fermentation but decreased gastrointestinal transit time. Involvement of RS in lipid metabolism was also discussed. RS reduces glycemic index and improves glucose tolerance in rats. RS improves mineral availability through increased absorption in the large intestine. Some effects of RS on large intestinal defects were ascribed to fermentation products, short-chain fatty acids.

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We calculated daily dietary fiber intake of different age groups and analysed intake pattern of general population in Aomori Prefecture based on the result of the Aomori Nutrition Survey. Results obtained were as follows: Dietary fiber intake increases in both sexes with age, 50's in men and 60's in women giving the maximum values. The lowest intakes of dietary fiber were calculated in 20's for men and in 15-19 years old for women. Furthermore, there was substantially no difference in dietary fiber intake between men and women. In both sexes, dietary fiber intakes from cereal, potatoes and seaweeds were not different among all ages, but the intakes from vegetables, beans and fruits increased with aging . As family number decrease and the kind of food increased, the daily dietary fiber intake increased.

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There are controversial results for the effects of dietary fiber intake on zinc absorption. In the present study, we examined the effects of five refined water soluble dietary fibers with different physical and chemical properties on zinc absorption in rats. Sprague-Dawley male rats, weighing 50 g, were acclimated and fed a basal diet (control) or five test diets containing 50 g/kg diet fiber sources, arabinogalactan, partially hydrolyzed guar gum (GGH), carboxymethyl cellulose (CMC), psyllium and guar gum for 3 weeks. There was no difference in body weight and food intake among the six groups of rats. Apparent zinc absorption (rates and amounts) for 3 days from Day 8 and Day 18 after the starting test diets were lower in rats fed CMC compared with the control group. In later test period, zinc absorption was lower in the psyllium group than the two low viscous fibers, ara binogalactan and GGH-fed groups. However, high viscosity may not be involved in lowering zinc absorption because the absorption in rats fed guar gum, the highest viscous fiber, was not lower than in rats of the control group. Changes in femur zinc concentration among the groups were similar to the changes in the zinc absorption. In conclusion, CMC ingestion was clearly lowered zinc absorption, but other four soluble fibers were not.

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Dietary fiber has been defined as "Food components that are not digested by the human digestive enzymes", and reported to have various physiological effects. The intake of the Japanese population was over the recommended intake of dietary fiber ( 20 25 g/day as an adult) until the 1960s, however, thereafter the intake has gradually decreased and reached to approximately 16 g/day in the 1990s, of which is defected approximately 5g/day. The effects of the ingestion of cookies containing indigestible dextrin(ID-cookies) were investigated focusing on defecation and fecal condition in 39 healthy human subjects(12 men and 27 women). Each subject was daily given three pieces of ID-cookies (total: 26 g, ID: 5 g) for twenty days, and compared with a non-ingestion period. Fecal volume and the frequency of defecation in the group of tend to constipate were significantly increased by the cookies-ingestion ( p < 0.05 ). Fecal conditions such as shape, smell and feeling after defecation were improved by self-judgement in ll subjects. These results demonstrated that the ingestion of cookies containing indigestible dextrin improved defecation and fecal condition of healty human subjects with a tendency to be constipated.

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