Abstract: It has long been proposed that nanostructured liquid crystal phases may be formed on digestion of lipids when the transient lipid concentrations and packing are amenable to structure formation, however the in situ observation of such structures during the digestion of pharmaceutically and nutritionally bio-relevant systems is a recent development. In situ scattering and microscopic observations have revealed a range of nanostructures are formed transiently, and at the end point of digestion of milk fats and pharmaceutical systems. The formation of structure in such systems is highly dependent on the presence of other amphiphilic components such as bile salts. The concept of the formation of nanostructured materials during lipid digestion has also been harnessed to deliberately generate persistent dispersed cubic phase systems with a complete absence of contaminating liposomes. These materials have drug delivery and biosensing applications to name a few.