Br J Nutr 2003 Feb;89(2):239-48 Related Articles, Links
Casein and whey exert different effects on plasma amino acid profiles, gastrointestinal hormone secretion and appetite.
Hall WL, Millward DJ, Long SJ, Morgan LM.
Centre for Nutrition and Food Safety, School of Biomedical and Life Sciences, University of Surrey, Guildford, Surrey GU2 7XH.
[email protected]
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.
PMID: 12575908
[PubMed - indexed for MEDLINE]
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Slow and fast dietary proteins differently modulate postprandial protein accretion.
Boirie Y, Dangin M, Gachon P, Vasson MP, Maubois JL, Beaufrere B.
Laboratoire de Nutrition Humaine, Universite Clermont Auvergne, Centre de Recherche en Nutrition Humaine, BP 321, 63009 Clermont-Ferrand Cedex 1, France.
The speed of absorption of dietary amino acids by the gut varies according to the type of ingested dietary protein. This could affect postprandial protein synthesis, breakdown, and deposition.
To test this hypothesis, two intrinsically 13C-leucine-labeled milk proteins, casein (CAS) and whey protein (WP), of different physicochemical properties were ingested as one single meal by healthy adults. Postprandial whole body leucine kinetics were assessed by using a dual tracer methodology.
WP induced a dramatic but short increase of plasma amino acids.
CAS induced a prolonged plateau of moderate hyperaminoacidemia, probably because of a slow gastric emptying.
Whole body protein breakdown was inhibited by 34% after CAS ingestion but not after WP ingestion.
Postprandial protein synthesis was stimulated by 68% with the WP meal and to a lesser extent (+31%) with the CAS meal.
Postprandial whole body leucine oxidation over 7 h was lower with CAS (272 +/- 91 micromol.kg-1) than with WP (373 +/- 56 micromol.kg-1). Leucine intake was identical in both meals (380 micromol.kg-1).
Therefore, net leucine balance over the 7 h after the meal was more positive with CAS than with WP (P < 0.05, WP vs. CAS).
In conclusion, the speed of protein digestion and amino acid absorption from the gut has a major effect on whole body protein anabolism after one single meal. By analogy with carbohydrate metabolism, slow and fast proteins modulate the postprandial metabolic response, a concept to be applied to wasting situations.
PMID: 9405716 [PubMed - indexed for MEDLINE]
