Development of an innovative method for reducing colon-cancer-inducing secondary bile acid formation through enhancement of anaerobic respiration of the intestinal bacteria

在大肠中形成的一些次级胆汁酸被认为是结肠癌的危险因素。在这项研究中，研究了一种新的方法来减少这种由肠道微生物的诱导代谢形成的次生胆汁酸。我们测试了通过引入厌氧呼吸来增强负责的肠道微生物的氧化代谢是否可以减少目标次级胆汁酸。因此，给大鼠喂食富马酸钠补充饮食以增强肠道微生物的厌氧呼吸。虽然研究结果提示脱氧胆酸（一种具有代表性的结肠癌致继发性胆汁酸）的相对丰度可能会降低，但观察到的效果并不实际适用，因为需要高剂量的富马酸（占饮食的5~10%），导致实验大鼠腹泻。因此，改进富马酸给药的方法，如包封，可能是实现这一目标所必需的。

Some secondary bile acids formed in the large intestine are known as a riskfactor of colon cancer. In this study a novel method that reduces such secondary bile acids formed by thereductive metabolism of gut microbes were investigated. We tested if the enhancement of oxidativemetabolism of the responsible gut microbes by the introduction of anaerobic respiration can reduce thetarget secondary bile acids. Thus, rats were fed sodium fumarate-supplemented diet to enhanceanaerobic respiration of the gut microbes. Although the results suggested a possibility of decreasingrelative abundance of deoxycholic acid, a representative colon-cancer-inducing secondary bile acid, theobserved effects were not practically applicable, because high dose of fumarate was required (5~10% ofthe diet), which resulted in the diarrhea in rats experiments. Therefore, improved method of fumaratefeeding, e.g. encapsulation, might be necessary to achieve this goal.