Rats have an enlarged cecum to be considered as an adaptive structure to variable food quality. The cecum plays an important role to utilize indigestible and fermentable food materials in the rat. Cecectomy results in faster transit of digesta connecting lower digestibilities of food components in the rat. The response of the transit and retention of digesta to the feeding of indigestible food materials is similar to that in human, where the inverse response is often recognized in normal rats, suggesting that cecectomized rats are useful in the study concerning digesta movement in the gut. Some of nutritional and physiological effects of dietary fiber and fermentable food components are extinguished by cecectomy. Some inverse results are obtained in the rats with or without cecum in the nutritional and physiological studies. Fermentation in the large gut is modified largely by cecectomy. Although the cecectomized rat has some possibilities as a useful experimental animal, there is a limitation to use the cecectomized rat as an experimental animal in the study of the function of fermentable food materials. Further comparative studies are needed in the functions of the digestive tract between human and the cecectomized rat for the strict qualification of the usefulness in human nutrition studies.

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We examined the antioxidant activity of lignin which is a kind of dietary fiber by using a new lignin derivative, 'lignophenol'. Lignophenol is close to natural lignin compared with any other lignin derivatives prepared with the former methods. Twelve kinds of lignophenols were prepared from beech (Fagus crenata Blume) and hinoki (Cryptomeria japonica D.Don) by a phase-separative reaction system composed of cresol and sulfuric acid. The antioxidant activity of lignophenol against the oxidation of linoleic acid was determined by the peroxidative value (POV) and the thiobarbituric acid (TBA) methods. All lignophenols effectively prevented the oxidation of lipids as same as BHA, and the lignophenols treated with alkali and acetylated had high activity. The antioxidant activity of lignophenol from hinoki that has guaiasyl (o-methoxyphenolic) groups tended to be higher than that of beech that has guaiasyl and syringyl groups.

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We determined the resistant starch (RS) content of high amylose wheat (HAW) which was recently crossbred in Japan. By the crossbreeding, the endosperm starch content of HAW was decreased about 20% in comparison with that of normal wheat. HAW contained 1.3% of RS in the starch, and the content was six times higher than that of normal wheat starch. After heat-moisture treatment the RS content of normal wheat and HAW starch were 0.5 and 2.7%, respectively. The RS content of HAW was doubled of untreated one. In case of corn starch after heat-moisture treatment, the RS content of two type of high amylose corn, HAC and A632 increased to 26.2% and 2.7%, respectively. The RS of normal corn starch was scarcely contained. From the results, the heat-moisture treatment may be able to increase the RS content of wheat, although the treatment of wheat starch was not effective as that of corn starch.

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We examined the effect of oatmeal containing β-glucan on blood lipids and its safety of long-term intake in Japanese men with boundary and hypercholesterolemia. A total of 48 men with boundary and mild hypercholesterolemia were divided into 3 groups. Group A was given four pieces of the placebo cookies, group B was given the test oatmeal cookies containing oatmeal at 30 g/4 pieces, and group C was given the same cookies containing oatmeal at 45 g/4 pieces, once a day for 12 weeks, respectively. These results were as follows: The serum total cholesterol level for the group C with boundary hypercholesterolemia decreased with a significant difference in comparison with the groups of A and C (p<0.05). There were no abnormal hematological changes, no abnormal level of physiochemical substances in blood, and clinical changes which were indicated any adverse reactions in the groups given test cookies. These results indicate that the supplementation of oatmeal at 45g/day (1.6g β-glucan/day) decreases the serum total cholesterol concentration and has no adverse effect in men with boundary hypercholesterolemia.

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