Casein and whey exert different effects on plasma amino acid profiles, gastrointestinal hormone secretion and appetite

• Published in: British journal of nutrition Vol. 89; no. 2; pp. 239 - 248
• Main Authors: Hall, W. L., Millward, D. J., Long, S. J., Morgan, L. M.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.02.2003; CABI Pub
• Subjects: Adult; amino acid composition; Amino acids; Amino Acids - blood; Analysis of Variance; Biological and medical sciences; casein; Caseins; Cholecystokinin; Cholecystokinin - blood; dairy protein; Dietary protein; Dietary Proteins - administration & dosage; digestion; energy intake; Female; food intake; Fundamental and applied biological sciences. Psychology; gastric emptying; Gastric Inhibitory Polypeptide - blood; Gastrointestinal hormones; Gastrointestinal Hormones - metabolism; gastrointestinal system; Glucagon - blood; Glucagon-Like Peptide 1; hormone secretion; Humans; Hunger; Insulin - blood; Male; Metabolites; Peptide Fragments - blood; Postprandial amino acids; Postprandial Period; Protein Precursors - blood; Satiation; Satiety; Single-Blind Method; Vertebrates: digestive system; whey; Postprandial amino acids; Dietary protein; Satiety; Glucagon-like peptide-1; Cholecystokinin; Appetite; Human; Supplemented diet; Whey; Neuropeptide; Protein; Dietary protein: Satiety: Cholecystokinin: Glucagon-like peptide-1: Postprandial amino acids; Feeding; Glucagon like peptide 1; Endocrine secretion; Gastrointestinal hormone; Casein; Aminoacid; Macronutrient; Nutritional status
• ISSN: 0007-1145; 1475-2662
• DOI: 10.1079/BJN2002760

Protein, generally agreed to be the most satiating macronutrient, may differ in its effects on appetite depending on the protein source and variation in digestion and absorption. We investigated the effects of two milk protein types, casein and whey, on food intake and subjective ratings of hunger and fullness, and on postprandial metabolite and gastrointestinal hormone responses. Two studies were undertaken. The first study showed that energy intake from a buffet meal ad libitum was significantly less 90 min after a 1700 kJ liquid preload containing 48 g whey, compared with an equivalent casein preload (P<0·05). In the second study, the same whey preload led to a 28 % increase in postprandial plasma amino acid concentrations over 3 h compared with casein (incremental area under the curve (iAUC), P<0·05). Plasma cholecystokinin (CCK) was increased by 60 % (iAUC, P<0·005), glucagon-like peptide (GLP)-1 by 65 % (iAUC, P<0·05) and glucose-dependent insulinotropic polypeptide by 36 % (iAUC, P<0·01) following the whey preload compared with the casein. Gastric emptying was influenced by protein type as evidenced by differing plasma paracetamol profiles with the two preloads. Greater subjective satiety followed the whey test meal (P<0·05). These results implicate post-absorptive increases in plasma amino acids together with both CCK and GLP-1 as potential mediators of the increased satiety response to whey and emphasise the importance of considering the impact of protein type on the appetite response to a mixed meal.