The four major bile acids found in humans are synthesized from:

When considering bile as a digestive secretion, it is the bile acids that represent the most impoant components. They are synthesized from cholesterol and secreted into the bile conjugated to glycine or taurine, a derivative of cysteine. Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. (2012). Chapter 25. Overview of Gastrointestinal Function & Regulation. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks (Eds), Ganong's Review of Medical Physiology, 24e.