Primary bile acids are produced in the liver, whereas secondary bile acids, such as lithocholic acid (LCA), are generated by gut bacteria from primary bile acids that escape the ileal absorption. Besides their well‐known function as detergents in lipid digestion, bile acids are important signaling molecules mediating effects on the host's metabolism.

中文翻译：

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胆酸可提高果蝇黑腹果蝇的存活率

一级胆汁酸是在肝脏中产生的，而二级胆汁酸（如石胆酸（LCA））则是由肠道细菌从一级胆汁酸中产生的，这些胆汁酸逃避了回肠的吸收。胆汁酸除了具有众所周知的脂质消化中去垢剂的功能外，还具有重要的信号分子介导对宿主代谢的作用。