Studies on the increased incidence rate of colon cancer due to the excess intake of water soluble dietary fiber

点击翻译按钮获取中文摘要

In order to make clear whether it is necessary to lay a guideline for the intake ratio of water souble dietary fiber to the water insoluble one, we investigated the effect of feeding guar gum or guar gum plus cellulose on the chemical carcinogenesis by 1,2-dimethylhydrazine of rat colon. The results obtained were as follows.1. We confirmed the precedent reports indicating the enhancement of tumor formation by feeding guar gum with statistical significance.2. We disclosed the fact that the enhanced tumor formation was suppressed completely when 2/3 of the guar gum was replaced with cellulose.3. In both cases of 1. and 2.,serum cholesterol and tryglyceride levels were decreased significantly, and fecal excretion per day of total bile acids were almost doubled.4. In the case of 1., the fecal concentration of total bile acids was in the same level to or significantly higher than the control (no dietary fiber fed). In the case of 2., however, the fecal concentration of total bile acids was significantly lower than or almost half of the control.5. In the case of 1., de-conjugation activities were higher, and in the case of 2., they were lower than the control group. Accordingly, the de-conjugation of the excretion form of DMH to the digestive tract, the glucuronate conjugate of methylazoxymethanol was deduced to be more complete in the case 1. when compared with the case 2 rats.6. 7-α-dehydroxylation activity was deduced to be lower in the case 1. rats than the control or case 2. rats on the fact that the amount of lactate, acetate or propionate detected in the cecum was almost double in the case 1. compared to the control rats or case 2. rats. Consequently, the concentration of fecal secondary bile acids of case 1. rats was the lowest among other groups and the neoplasma detected in case 1. rats were all adenoma. Thus, it is to be desired that the guideline for balanced intake of dietary fiber is officially published.