Impact of digestion on the antimutagenic activity of the milk protein casein

Abstract

The effect of caseinate and soy protein on the mutagenicity induced by N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) was assessed in in-vitro and in-vivo studies using a host-mediated assay. Of the two dietary proteins tested, only casein showed antimutagenic activity. Moreover, evidence is presented that enzymatic digestion of sodium-caseinate greatly improved its antimutagenic potential. It is suggested that the molecular structure of a protein determines its protective effect against mutagens. A stronger protection appears to correspond with a lack of secondary and tertiary structure. These findings shed new light on the possible prevention of mutagenesis and/or carcinogenesis by food proteins, with an unique role for milk proteins.