Bile acids occupy a central position in in the absorption, excretion and metab- olism of lipids within the body. Our understanding of their unique properties has illuminated many biochemical and biophysical processes. Animals have evolved a unique system of preserving these important detergent-like molecules within the body and reusing them many times - the enterohepatic circulation. Disorders of the enterohepatic circulation contribute to a correspondingly wide range of diseases, and recent developments have centred in particular on cholesterol gallstone disease and bile acid diarrhoea....