• Food Science and Industry
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• v.51 no.4
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• pp.302-312
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• 2018

Bioactive peptides generated from milk proteins play an important role in the prevention and alleviation of diabetes. Whey proteins possess direct insulinotropic effect by amino acids (especially branch chain amino acids) produced through its gastrointestinal digestion. Additionally, blood glucose level can be lowered by gut hormone which called incretin [glucose dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1)]. However, physiological effects of incretin readily disappeared by dipeptidyl peptidase-4 (DPP-4) causing degradation of GLP-1. Several DPP-4 inhibitors are currently used as therapeutic medicines for the treatment of type II diabetes. More than 60 natural peptide (2-14 amino acids) DPP-4 inhibitors were identified in milk proteins. Peptide DPP-4 inhibitors act as substrate inhibitor and delay breakdown of GLP-1 both in vitro and in vivo. This review summarizes nutritional quality of milk proteins, absorption and mode of action of bioactive peptides, and finally up-to-dated knowledge on DPP-4 inhibitory peptides derived from milk proteins.

• Journal of Applied Biological Chemistry
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• v.64 no.1
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• pp.75-81
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• 2021

Recent gut microbiota studies have revealed the important roles of gut microbiota for our health. Increasing numbers of health functional foods have been developed every year. Development of functional food often includes ex- and in-vivo experiment to verify the beneficial effects of the functional food. To investigate effects of functional food on gut microbiota, animal models were often conducted. Beneficial effects of food can be evaluated based on how gut microbiota was shifted by food, which results in either increase in beneficial bacteria, decrease in potentially pathogenic bacteria or both. As animal experiments are generally time-consuming and laborious, we investigate how well in-vitro investigation of fecal microbiota may reflect dietary health benefits. Here, we tested 15 kinds of diets using two human subjects' fecal materials. Our results showed varying gut microbiota shifts according to diets, which suggested generally known beneficial diets (i.e. Kimchi, Chunggukjang) increased Lactobacillus and Bifidobacterium. Therefore, we suggest that in vitro fecal microbiota analysis could be used to evaluate beneficial effects of diets. Moreover, this method may be ideal to establish personalized diet.