Bile salts (BS) are bio-surfactants present in the gastrointestinal tract (GIT) that play a crucial role in the
digestion and absorption of nutrients. The importance of BS for controlled release and transport of lipid
soluble nutrients and drugs has recently stimulated scientific interest in these physiological compounds. BS
are so-called facial amphiphiles showing a molecular structure that is very distinct from classical surfactants.
This peculiar molecular structure facilitates the formation of dynamic aggregates able to solubilise and
transport lipid soluble compounds. The detergent nature of BS has been studied in the literature, mostly
concentrating on the self-assembly behaviour of BS in solution but also in relation to protein denaturation and
its effect on improving proteolysis. In contrast, the affinity of BS for hydrophobic phases has received less
attention and studies dealing directly with the interfacial behaviour of BS are very limited in the literature.
This is despite the fact that the interfacial activity of BS plays a vital role in fat digestion since it is closely
involved with lypolisis. BS adsorb onto fat droplets and can remove other materials such as proteins,
emulsifiers and lipolysis products from the lipid surface. The unusual surface behaviour of BS is directly
related to their intriguing molecular structure and further knowledge could provide an improved
understanding of lipid digestion. This review aims to combine the new insights gained into the surface
properties of BS and their role in digestion. A better understanding of surface activity of BS would allow
manipulation of physico-chemical and interfacial properties to modulate lipid digestion, improve
bioavailability of lipid soluble nutrients and reduce absorption of saturated fats, cholesterol and trans fats.