Satoru Iwane

Proposal for recommended level of dietary fiber intake in Japan

Abstract In this report, we attempt to propose a recommended level of dietary fiber (DF) for the Japanese from several epidemiological reports. The authors previously investigated the daily DF intake in 50 patients with colon polyp, 33 patients with colon diverticulosis, 45 patients with colorectal cancer, and two groups 84 and 45 control subjects; the values obtained were 18.2, 17.4, 14.9, and 21.1 and 19.9 g, respectively. In another study, of the 5 regions in Japan, in only one, Aomori, where the rate of the colon diverticulosis detection was the lowest, did the DF intake exceed 20 g. Furthermore, in Japan the incidence of colorectal cancer showed a marked increase after 1955. It was assumed that the period between the diagnosis of colorectal cancer and death was 15 years, and that the DF intakes at this time (before 1940) to had contributed to the development of the disease. However unfortunately daily DF intake before 1940 in Japan were unknown, and we have only data 25.0 g in 1946. Thus, it is proposed that the recommended level for daily DF intake in Japanese be set at about 20–25 g, i.e. 10 g per 1,000 kcal.

New method for the determination of fecal consistency and its optimal value in the general population

Background : Although fecal consistency is an important factor, there has been only one study measuring this parameter. We developed a new method to measure fecal consistency and studied the relationship between fecal consistency and other fecal factors, including water content and weight.

Inhibitory Effect of Small Amounts of Cellulose on Colonic Carcinogenesis with Low-Dose Carcinogen

This study set out to evaluate the effects of dietary fiber on cancer development in the large bowel under in vivo experimental conditions as similar as possible to those under which this cancer develops in vivo in humans. Forty-eight Sprague-Dawley rats were divided into three groups that were fed either a nonfiber diet or a 3 g or 10 g/100 g cellulose diet in this experiment, and all groups received doses of a mild carcinogen, 1,2-dimethylhydrazine (5 mg/kg body weight) for 50 weeks. Following endoscopic observation of the large bowel, we found that the induction rates of tumor in the cellulose groups were significantly lower than that in the nonfiber diet group, both endoscopically and histologically. No differences were seen between the 3% and 10% cellulose groups in suppressing carcinogenesis. It is likely that the inhibitory effect of 3% cellulose could be confirmed only by a long-term experiment on carcinogenesis following the administration of a low dose of carcinogen.

Changes in Intraluminal Pressure in Rat Large Intestines with Aging and Effects of Dietary Fiber

Changes in intraluminal pressure in rat colon with aging and with the effects of dietary fiber were measured. A pressure sensor was inserted into the rat large intestine under endoscopic guidance. The intraluminal pressure curve in the colon was recorded, and the motility index was calculated by this curve. The rats were divided into three groups with a fiber-free diet, a cellulose diet (10% w/w), or a pectin diet (10% w/w). Intraluminal pressure was measured in the proximal, middle, and distal colon at 2, 4, 8, 12, and 16 months after birth. Intraluminal pressure in three sites increased with age and decreased in the latter half of the study. The motility index was lower during the course in the fiber groups, especially the pectin group more than the nonfiber group. This result suggests that long-term ingestion of dietary fiber might have a prophylactic effect on the development of diverticula.

ENDOSCOPIC EVALUATION OF THE PREVENTIVE EFFECT OF WHEAT BRAN AGAINST 1,2-DIMETHYLHYDRAZINE INDUCED LARGE BOWEL CARCINOGENESIS IN RATS

We evaluated the preventive effects of wheat bran (40%, weight percent of diet) on the development of large bowel carcinoma induced by weekly intraperitoneal administration of 25 mg/kg (body weight) of 1,2-dimethylhydrazine over 19 weeks in the rat. Feces number and volume per pellet in wheat bran diet group were significantly greater than those in basal diet group, and the induction rates of tumor in the wheat bran diet group was found to be significantly lower than that in the basal diet group. These results suggested that wheat bran was effective in inhibiting large bowel carcinogenesis, and that the increased fecal weight and volume from wheat bran may be involved in such an inhibitory effect.

A New Method for Measurement of Gastric and Colonic Lesions with an Electronic Endoscope and Image Processor

In order to measure the sizes of gastric and colonic lesions endoscopically, we established a system composed of an electronic endoscope, image processor, and personal computer. The long and short diameter of the lesion were calculated by a program which corrected the curvature radius of the lens of the endoscope and variables. 1) To evaluate its accuracy, we measured a 10 mm scale spherical model at different distances from the lens of the endoscope. The mean value was 9.7 mm, ranging from 9.0 to 10.9 mm. The rate of error was –0.38±4.4 % (mean±SE). 2) Using this system, we measured the sizes of 34 gastric and colonic lesions in 34 patients (3 with gastric cancers, 20 with gastric polyps, and 11 with colonic polyps), and compared them with the real sizes of the resected or polypectomized specimens. The rate of error was–1.1±1.3% (mean±SE). The results showed that our system was useful to evaluate the accurate sizes of gastric and colonic lesions endoscopically.