Table 1.

A summary of bioactive peptides released during the enzymatic digestion of dairy proteins (bovine), and their in vitro and in vivo activities related to the control of food intake and glucose homeostasis.

Source	Peptides	Actions	References
β-lactoglobulin	ALPMH	-stimulates CCK secretion in vitro	[30]
β-casein (A1 genetic variant)	YPFPGPI YPFPGPI   FPGPI	-opiod receptor agonist, -delays gut transit, -stimulates somatostatin release in vivo, -other μ-opiod receptor mediated effects in the gut, -up-regulation of DPP-IV espression in the small intestine (non opiod effect), -stimulate CCK secretion in vitro	[109,110] [113] [53] [8,107]
k-casein Whey protein fraction	Glycomacropeptide (GMP)	-stimulates CCK secretion from isolated rat intestine, -stimulates the release of satiety enteric hormones in mice, by altering the gut microbiota composition, -contradictory results as to the effects on appetite, food intake and enteric hormone release in humans,	[115] [116] [118,119,120,121,122]
Caseins Whey proteins	DPP-IV inhibitory peptides LKPTPEGDL, LPYPY, IPIQY, IPI, WR LPQNIPPL	-inhibit DPP-IV protease activity in vitro -possible delay of incretin hormone (GLP-1 and GIP) degradation and improvement of the control of postprandial glucose levels (systemic effect), -possible local action as inhibitors of DPP-IV activity in the gut (brush border of intestinal mucosa and gut microbiota) No clear evidence of their passage across the intestinal epithelial barrier into circulation -DPP-IV inhibitors in vitro, can cross an epithelial cell monolayer (Caco-2 cells) in vitro -DPP-IV inhibitor in vitro, improves postprandial glucose control in rats	[49,50,51,52,125,126] [134] [126,129] [8,132]
β-lactoglobulin Whey protein isolate	α-glucosidase inhibitory peptides AP and other peptides (not isolated and identified)	-inhibit α-glucosidase activity in vitro -inhibit α-glucosidase activity in vitro, -delay glucose absorption after meal in prediabetic subjects	[85,136,137] [86]
β-lactoglobulin	LIVTQTMKG	-decreases acylated ghrelin release in vitro, -decreases plasma ghrelin levels and food intake in fasted mice after oral administration	[138]
β-lactoglobulin	HIRL	-reduces food intake in fasted mice after oral-, ic- or ip administration	[139]
β-lactoglobulin	MH	-anxiolytic-like dipeptide, -increases insulin sensitivity in mice and Akt phosphorylation (insulin receptor signalling) in hepatocytes and skeletal muscle cells in vitro and in vivo	[140]
α-S1-casein	YLG	-reverses cognitive decline in mice fed a high-fat diet after oral administration (possibly direct effects on neuronal cells or indirect effects mediated by peripheral actions, including actions on metabolic health)	[143]
caseins	Ghrelinergic peptide mixtures	-activate ghrelin receptor (GHSR1a) in vitro -induce a short-term increase of food intake in rats after oral administration (not so after ip administration)	[144]
sodium caseinate	RF	-stimulates CCK secretion in vitro, -delays gut transit of food after oral administration and decreases food intake after ip administration in mice	[8,106,124]

Abbreviations: ip, intraperitoneal; ic, intracerebroventricular; GLP-1, glucagon-like peptide-1; GIP, glucose-dependent insulinotropic peptide; CCK, cholecystokinin.