Potential implications of food proteins-bile salts interactions

This review is focused at discussing the existing literature on proteins/peptides ? bile salts (BS) interactions regarding of the physiological processes they can modulate, as well as to analyze the in vitro assays mostly used to assess protein/peptides-bile salt interactions. When partially hydrolyzed proteins by pepsin in the stomach are flushed into the duodenum, they come into contact with the enzymes secreted by the pancreas (trypsin, chymotrypsin and lipase/colipase) and with the BS secreted by the gallbladder. It is at this stage where different types of interaction between the peptides present and the BS can take place, which can have potential health implications affecting (a) bile excretion, (b) the transport and absorption of hydrophobic molecules (cholesterol, fatty acids, vitamins and fat-soluble bioactive compounds) and (c) the degree and rate of lipolysis of dietary lipids. The molecular mechanisms underlying the modulation of processes (a) has to do with the ability of peptides to bind and precipitate BS, producing their elimination in the feces, whereas the modulation of process (b) and (c) are related to the role that BS have in the duodenal transport and absorption of lipids, fatty acids or any other hydrophobic molecule. In spite of a general evidence supporting that all food proteins or their hydrolysates/peptides have a certain degree of interaction with bile salts when testing their in vitro binding capacity or their influence on the micellar solubility of hydrophobic molecules, more studies are needed at a molecular level and using in vitro models that better simulate gastrointestinal digestion, to elucidate the mechanism underlying those effects.