异石胆酸（Isolithocholic acid，又称β-石胆酸）是石胆酸的同分异构体，属于胆酸类化合物，可由石胆酸（Lithocholic acid）或3α-硫酸化石胆酸（Lithocholic acid 3α-sulfate）经微生物代谢产生。

[1] Thanissery R, Winston JA, Theriot CM. Inhibition of spore germination, growth, and toxin activity of clinically relevant C. difficile strains by gut microbiota derived secondary bile acids. Anaerobe. 2017 Jun;45:86-100. doi: 10.1016/j.anaerobe.2017.03.004. Epub 2017 Mar 6. PMID: 28279860; PMCID: PMC5466893.[2]Lin H, An Y, Tang H, Wang Y. Alterations of Bile Acids and Gut Microbiota in Obesity Induced by High Fat Diet in Rat Model. J Agric Food Chem. 2019 Apr 3;67(13):3624-3632. doi: 10.1021/acs.jafc.9b00249. Epub 2019 Mar 20. PMID: 30832480.