Low protein/low methionine/high carbohydrate diets induce hyperphagia, increase energy expenditure and FGF21, but modestly affect adiposity infemale BalbC mice.

International audienceTitle: Low protein/low methionine/high carbohydrate diets induce hyperphagia, increase energy expenditure and FGF21, but modestly affect adiposity in female BalbC mice ABSTRACT PREVIEW Author(s)ObjectivesLow-protein diets are reported to induce hyperphagia in an effort to fulfil protein needsbut at the expense of energy balance with a risk to gain in adiposity. However, differentstudies conducted on low-protein diets in animal and human did not confirm weight andbody fat gain because an increased energy expenditure compensated more or lesscompletely for the increase in energy intake and prevents the gain in adiposity. Thepresent study evaluated in mice the consequence of protein restricted diets combined withprotein quality (milk protein versus soy protein with slight methionine deficiency) onenergy intake, energy expenditure and adiposity and the role of FGF21 in the response tothese protein restricted dietsMethodsThe present study investigated in female BalbC mice the behavioral, metabolic andphenotypic responses to 8 weeks feeding a very low (3%), moderately low (6%) or adequate(20%) dietary protein content and whether methionine scarcity in the dietary protein (Soyprotein vs casein) affected these responses. Food intake, body weigh, adiposity (assessedby DEXA), were measured throughout the study and body composition determined bydissection at the end of the study. Plasma, liver, muscle, adipose tissue and hypothalamussamples were collected for nutrient, hormones and/or gene expression measurements.The different mice groups : P20C 20% casein, P20S 20% soy protein, P6C 6% casein, P6S 6%soy protein, P6S-Cor 6% soy protein corrected for methionine, P3C 3% caseinResultsIn female adult BalbC mice, a decrease in dietary casein from 20% to 6% and 3% increasedenergy intake and slightly increased adiposity, and this response was exacerbated with soyproteins with low methionine content compared to milk protein (figure 1). Lean body masswas reduced in 3% casein fed mice but preserved in all 6% fed mice. The effect on fat masswas however limited because total energy expenditure (TEE) increased to the same extentas energy intake (figure 2). In plasma, when protein was decreased, IGF-1 decreased, FGF21increased and plasma FGF21 was best described by using a combination of dietary proteinlevel, protein to carbohydrate ratio and protein to methionine ratio in the diet (figure 3). Insulinresponse to an oral glucose tolerance test was reduced in soy fed mice and in low-proteinfed mice. Low-protein diets did not affect Ucp1 but increased Fgf21 in brown adiposetissue and increased Fgf21, Fas, and Cd36 in the liver. In the hypothalamus, Npy wasincreased and Pomc was decreased only in 3% casein fed mice.Conclusions In conclusion, reducing dietary protein and protein quality increases energy intake but alsoenergy expenditure resulting in an only slight increase in adiposity. In this process FGF21 isprobably an important signal that responds to a complex combination of proteinrestriction, protein quality and carbohydrate content of the diet

Intestinal kinetics from digestion of milk proteins in humans

Objective. We aim to assess in humans the intestinal digestion of two protein fractions from milk, i.e. a soluble (SP) and non-soluble (casein; CAS) proteins, that exhibit opposite chemical and digestive characteristics

Increasing Protein at the Expense of Carbohydrate in the Diet Down-Regulates Glucose Utilization as Glucose Sparing Effect in Rats

High protein (HP) diet could serve as a good strategy against obesity, provoking the changes in energy metabolic pathways. However, those modifications differ during a dietary adaptation. To better understand the mechanisms involved in effect of high protein diet (HP) on limiting adiposity in rats we studied in parallel the gene expression of enzymes involved in protein and energy metabolism and the profiles of nutrients oxidation. Eighty male Wistar rats were fed a normal protein diet (NP, 14% of protein) for one week, then either maintained on NP diet or assigned to a HP diet (50% of protein) for 1, 3, 6 and 14 days. mRNA levels of genes involved in carbohydrate and lipid metabolism were measured in liver, adipose tissues, kidney and muscles by real time PCR. Energy expenditure (EE) and substrate oxidation were measured by indirect calorimetry. Liver glycogen and plasma glucose and hormones were assayed. In liver, HP feeding 1) decreased mRNA encoding glycolysis enzymes (GK, L-PK) and lipogenesis enzymes(ACC, FAS), 2) increased mRNA encoding gluconeogenesis enzymes (PEPCK), 3) first lowered, then restored mRNA encoding glycogen synthesis enzyme (GS), 4) did not change mRNA encoding β-oxidation enzymes (CPT1, ACOX1, βHAD). Few changes were seen in other organs. In parallel, indirect calorimetry confirmed that following HP feeding, glucose oxidation was reduced and fat oxidation was stable, except during the 1st day of adaptation where lipid oxidation was increased. Finally, this study showed that plasma insulin was lowered and hepatic glucose uptake was decreased. Taken together, these results demonstrate that following HP feeding, CHO utilization was increased above the increase in carbohydrate intake while lipogenesis was decreased thus giving a potential explanation for the fat lowering effect of HP diets

Les critères de qualité des protéines ont-il évolué?

International audienceLa qualité des protéines dépend de leur capacité à fournir des acides aminés indispensables en quantité suffisante pour permettre, notamment, une synthèse optimale des protéines corporelles. Plusieurs critères sont utilisés pour rendre compte de cette capacité, en se basant sur des mesures in vivo chez l’Homme ou sur modèle animal, ou sur l’analyse de la composition en acides aminés des protéines. Les approches in vivo sont, soit des mesures de croissance chez le rat (coefficient d’efficacité protéique), soit des mesures de biodisponibilité digestive (digestibilité, absorption) et métabolique (rétention azotée, valeur biologique) des protéines. Les mesures de digestibilité des protéines, et surtout des acides aminés, présentent des contraintes méthodologiques fortes et des développements ont été proposés récemment pour s’affranchir du recours à des méthodes invasives. Le critère basé sur la composition des protéines le plus utilisé est le PD-CAAS (score chimique corrigé de la digestibilité de la protéine). L’Organisation des Nations Unies pour l’alimentation et l’agriculture (FAO) a proposé en 2011 de le remplacer par le DIAAS (score chimique corrigé de la digestibilité des acides aminés) ce qui le rend plus difficile à déterminer en raison des freins méthodologiques relatifs à la mesure des digestibilités individuelles des acides aminés. Ces indices basés sur les scores chimiques dépendent par principe fortement de la composition de la protéine, mais aussi du profil de besoin en acides aminés de l’Homme dont la dernière mise à jour date de 2007

Déterminants de la biodisponibilité des protéines et des acides aminés

Conférence dans un atelier de microencapsulation, organisé par le Pôle Nutrition Santé Longévité, à Loo

Dietary protein and blood glucose control

International audienceTome´Purpose of review This review presents the different pathways by which protein and amino acid impact glucose control. The review more particularly discusses the contradictory effects reported in the literature on the involvement of amino acid on glucose production and in insulin secretion and sensitivity. Recent findings Some recent findings allow a better understanding of the direct and indirect mechanisms involved in the insulinotropic activity of some amino acids in pancreatic b-cell and in the production of glucose through liver gluconeogenesis that participates to improve the control of glycemia. In contrast, the potential deleterious effects of branched chain amino acid, and particularly leucine, hypothesized in previous publications, have been discussed in some recent publications. Summary These processes are of high clinical relevance since the role of protein and amino acid have been repeatedly discussed to improve insulin secretion in type 2 diabetes patients or in weight management strategy in overweight and obese individuals. In addition, whether blood amino acid could be used as biomarkers for the risk of type 2 diabetes needs to be discussed

Protein and amino acid digestibility of 15N Spirulina in rats

International audiencePurpose: Spirulina is often used as dietary supplement for its protein content and quality. However, in vivo data on protein digestibility are lacking. This study aims to determine nitrogen and amino acid digestibility in rats. A secondary objective was to test the effect of sonication prior to ingestion to break cell walls.Methods: Wistar rats were fed a single test meal containing 15N Spirulina that was either sonicated (n = 11) or not (control, n = 13). Rats were euthanized 6 h after the meal ingestion. Spirulina nitrogen digestibility was measured by assessment of 15N recovery in digestive contents. Amino acid digestibility was measured by quantification of the caecal amino acid content and their 15N enrichment.Results: Real fecal nitrogen digestibility was 86.0 ± 0.7%, without any differences between groups. Mean 15N amino acid caecal digestibility was 82.8 ± 1.3%, and values ranged between 77.9 ± 1.9% for serine and 89.4 ± 1.0% for methionine. No effect of sonication was observed. The most limiting AA was histidine, with a chemical score of 0.98 and a PD-CAAS of 0.84. Lysine was also limiting in a lesser extent.Conclusion: The nitrogen and amino acid digestibility of Spirulina is relatively low, and showed no effect of prior sonication. Its amino acid composition is relatively well balanced but not enough to compensate for the poor digestibility

Devenir digestif des matrices laitières: application aux fractions protéiques

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Stimulation of CCK and GLP-1 secretion and expression in STC-1 cells by human jejunal contents and in vitro gastrointestinal digests from casein and whey proteins

International audienceThe present study evaluates casein and whey protein gastrointestinal digests as inducers of CCK and GLP-1 secretion and expression in STC-1 cells. In vitro digests were characterized regarding protein, peptide and free amino acid content. Digests from the intestinal phase containing small size peptides and free amino acids behaved as more potent CCK inducers than digests from the gastric phase. However, GLP-1 release was maximized with casein gastric digests and whey protein intestinal digests. Human jejunal digests from the same substrates showed a comparable response, except for casein jejunal digests which exerted a higher effect than in vitro casein gastrointestinal digests. The gene expression experiments also showed increased CCK and GLP-1 mRNA levels but the differences between the gastric and gastrointestinal phases were not as pronounced as observed by quantifying the secreted hormone. Our results demonstrate that the degree of protein hydrolysis during digestion plays an important role in CCK and GLP-1 secretion.Graphical abstract: Stimulation of CCK and GLP-1 secretion and expression in STC-1 cells by human jejunal contents and in vitro gastrointestinal digests from casein and whey protein