Protein digestion, casomorphins, and fermented dairy products

This review describes a general concept of protein digestion and traditional views on the mechanisms of absorption of amino acids, di- and tripeptides on the example of milk protein. It covers the mechanism of milk fermentation by its own enzymes with the involvement of intestinal microflora. It also describes the ways of oligopeptide absorption, as well as pharmacological effects of biologically active oligopeptides, in particular casomorphine. We discuss the physiological role of casomorphins and some of their pharmacological effects on laboratory animals. Fermented dairy products are a good example of products containing casomorphins. We provide the definition of the ‘gut-brain axis’ with simultaneous nutrition of the brain and microbiota. Depending on fermentation of the product of bacterial hydrolysis by exoenzymes produced by starter or probiotic strains, casomorphins are generated in fermented dairy products. The mechanism of β-casamorphine action (especially in children) is particularly interesting for physiologists, pharmacologists, and psychologists, since their effects on cells and individual systems promote certain neurochemical reactions associated with behavior and vital activities in general. There is also an overview of studies analyzing food consumption and mood modeling with an evidence base for improving mental health and mood associated with consuming certain nutrients and foods, especially dairy products. Key words: casomorphins, fermented dairy products, children