Effect of glycomacropeptide fractions on cholecystokinin and food intake

Abstract

Glycomacropeptide (GMP) is the hydrophilic 64-amino acid C-terminal glycopeptide released into cheese whey when k-casein is cleaved by chymosin. GMP exists as a mixture of different glycoforms due to the carbohydrates sialic acid (N-acetylneuraminic acid, NeuNAc), galactose (Gal), galactosamine and glucosamine attached by O-glycosidic linkages. GMP reportedly stimulates the release of cholecystokinin (CCK), which may promote satiety. The objectives of the present study were to manufacture three glycoforms of GMP, minimally glycosylated GMP (3·5 (SD 0·1) % NeuNAc and 1·5 (SD 0·1) % Gal), glycosylated GMP (12·0 (SD 0·3) % NeuNAc and 4·2 (SD 0·2) % Gal) and a GMP-depleted whey protein concentrate, and to assess the effects of these fractions relative to glucose on CCK, subjective measures of satiety and food intake. In a randomised double-blind acute study, twenty overweight/obese males (56·9 (SD 7·2) years, 97·4 (SD 8·1) kg, 31·5 (SD 3·0) kg/m 2 ) were recruited to consume four 50 g preloads (two GMP preparations, GMP-depleted whey and glucose) containing 895 kJ. Blood samples and subjective measures of satiety were collected before and at 15, 30, 60, 90, 120 and 180 min after the consumption of preload, and CCK levels were measured. A lunchtime meal of hot food was provided from which subjects ate ad libitum until satisfied. Energy and nutrient intakes from the food consumed were calculated. There was no significant difference in CCK levels, subjective measures of satiety or food intake between treatments at the given preload level. These results suggest that the protein fractions at the dose employed do not influence satiety, CCK levels or energy intake at a subsequent meal.

Physico-chemical characterization of chitosan-based edible films incorporating bioactive compounds of different molecular weight

“…These differences are possibly related with the hydrophilicity of the different peptides. Although hydrophilicity of WPC hydrolysate was not characterized, literature reports that GMP is highly hydrophilic (Keogh et al, 2010), while lactoferrin presents both hydrophobic and hydrophilic areas in its conformation (Lu et al, 2005).…”

Milk protein for improved metabolic health: a review of the evidence

“…Supportive evidence however is lacking [106,107]. In an isoenergetic study of whey protein, whey protein plus GMP, whey protein-derived alpha-lactalbumin (α-lac), casein and non-dairy soy protein, it was α-lac that was shown to suppress intake relative to the other fractions [111], whilst in a study comparing various forms of GMP no differential effects on intake were reported [112]. In a recent study of overweight women from our laboratory we also found no differential effect of GMP on energy intake [113] when we gave matched beverages containing 25 g of whey protein concentrate, GMP, beta-lactoglobulin (β-lac) and colostrum-derived whey protein, although greater fullness was induced by β-lac [113].…”

Dietary bioactive peptides: Human studies

“…Test meal intake was not different by preload: GMP alone was not considered by the authors as critical in pre-meal whey-induced satiety; however, it may have a role in compensatory intake regulation. Other authors found no significant difference in CCK levels, neither subjective measures of satiety nor in food intake between treatments at the given preload level, whatever the degree of glycosylation of the GMP (Keogh et al, 2010).…”