Rôle signal des acides aminés et de la leucine dans les cellules hépatiques

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Les traitements de pasteurisation et de séchage de l'œuf entier ainsi que l'étuvage du blanc d'œuf modifient le coefficient d'efficacité protéique et la composition corporelle chez le rat

Les traitements de pasteurisation et de séchage de l'œuf entier ainsi que l'étuvage du blanc d'œuf modifient le coefficient d'efficacité protéique et la composition corporelle chez le ratLes traitements de pasteurisation et de séchage de l'œuf entier ainsi que l'étuvage du blanc d'œuf modifient le coefficient d'efficacité protéique et la composition corporelle chez le ra

O18: La texture de la nourriture affecte la satiété et les mécanismes centraux de la prise alimentaire chez l’homme : étude par IRM fonctionnelle

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Milk protein fractions moderately extend the duration of satiety compared with carbohydrates independently of their digestive kinetics in overweight subjects.

Digestive kinetics are believed to modulate satiety through the modulation of nutrient delivery. We hypothesised that the duration of satiety could be extended by modulating the kinetics of dietary amino acid delivery in overweight subjects, using snacks containing casein and whey protein. In the present study, eighty-two subjects underwent a first satiety test where they received a control snack containing 60 g maltodextrin. For the next 5 d, the subjects consumed a liquid protein snack containing 30 g carbohydrates and 30 g proteins (casein, whey protein or an equal mix of the two; n 26-28 per group). The subjects then underwent a second satiety test after ingesting the protein snack. The time period elapsing between the snack and request for lunch, food intake at lunch and satiety scores were recorded. A subgroup of twenty-four subjects underwent a digestive and metabolic investigation after ingesting their protein snack. Gastric emptying times were 2·5, 4 and 6 h for whey protein, mix and casein, respectively, displaying different kinetics of appearance of dietary N in plasma but without affecting pancreatic and gastrointestinal hormones. Compared with the control snack, proteins extended the duration of satiety (+17 min, P= 0·02), with no difference between the protein groups. The satiating effect of proteins was greater in subjects who ate their lunch early after the snack (below the median value, i.e. 2 h) at the control test (+32 min, P= 0·001). Energy intake at lunch was not modulated by proteins. The satiating effect of proteins is efficient in overweight subjects, especially when the duration of satiety is short, but independently of their digestive and plasma amino acid kinetics

Urinary medium-chained acyl-carnitines sign high caloric intake whereas short-chained acyl-carnitines sign high-protein diet within a high-fat, hypercaloric diet in a randomized crossover design dietary trial

The western dietary pattern is known for its frequent meals rich in saturated fat and pro-tein, resulting in a postprandial state for a large part of the day. Therefore, our aim was to investi-gate the postprandial glucose and lipid metabolism in response to high (HP) or normal (NP) protein, high-fat hypercaloric diet and to identify early biomarkers of protein intake and hepatic lipid accu-mulation. In a crossover design, 17 healthy subjects were randomly assigned to consume a HP or NP hypercaloric diet for two weeks. In parallel, a control group (CD; n = 10) consumed a weight-maintaining control diet. Biomarkers of postprandial lipid and glucose metabolism were measured in 24 h urine and in plasma before and following a meal challenge. The metabolic profile of urine but not plasma, showed increased excretion of13C, carnitine and short chain acyl-carnitines after adaptation to the HP diet. Urinary excretion of decatrienoylcarnitine and octenoylcarnitine increased after adaptation to the NP diet. Our results suggest that the higher excretion of short-chain urinary acyl-carnitines could facilitate the elimination of excess fat of the HP diet and thereby reduce hepatic fat accumulation previously reported, whereas the higher excretion medium-chains acyl-carnitine could be early biomarkers of hepatic lipid accumulation.</p

Energy restriction only slightly influences protein metabolism in obese rats, whatever the level of protein and its source in the diet

International audienceBACKGROUND: High protein (HP) diets during energy restriction have been studied extensively regarding their ability to reduce body fat and preserve lean body mass, but little is known about their effects on protein metabolism in lean tissues. OBJECTIVE: To determine the effects of energy restriction and protein intake on protein anabolism and catabolism in rats. METHODS: For 5 weeks, 56 male Wistar rats were fed an obesity induction (OI) diet. They were then subjected to a 40% energy restriction using the OI diet or a balanced HP diet for 3 weeks, whereas a control group was fed the OI diet ad libitum (n ¼ 8 per group). HP-restricted rats were divided into five groups differing only in terms of their protein source: total milk proteins, casein (C), whey (W), a mix of 50% C and W, and soy (n ¼ 8). The animals were then killed in the postprandial state and their body composition was determined. Protein synthesis rates were determined in the liver, gastrocnemius and kidney using a subcutaneous 13 C valine flooding dose. mRNA levels were measured for key enzymes involved in the three proteolysis pathways. RESULTS: Energy restriction, but not diet composition, impacted weight loss and adiposity, whereas lean tissue mass (except in the kidney) was not influenced by diet composition. Levels of neoglucogenic amino acids tended to fall under energy restriction (Po0.06) but this was reversed by a high level of protein. The postprandial protein synthesis rates in different organs were similar in all groups. By contrast, mRNA levels encoding proteolytic enzymes rose under energy restriction in the muscle and kidney, but this was counteracted by a HP level. CONCLUSIONS: In adult obese rats, energy restriction but not diet composition affected fat pads and had little impact on protein metabolism, despite marked effects on proteolysis in the kidney and muscle. INTRODUCTION Weight management strategies are designed to reduce body fat while causing no major reduction in lean tissue. The different strategies proposed 1,2 involve varying levels of energy restriction and modifications to the energy nutrient content of diets, such as limiting the consumption of fat or carbohydrate (CHO) and increasing the protein content. 3,4 Proteins have been the focus of particular study because of their satiating effect that might both reduce energy intake 5 and increase subject compliance with a diet. 6,7 In addition, a protein-rich diet may minimize the loss of lean body mass that is observed under a low-calorie diet. 8,9 The type of protein source may also exert an influence, as reported in rodent models. 10,11 The effects of energy restriction on anabolic and catabolic fluxes are poorly understood and the findings available, which differ regarding numerous parameters (model, duration, degree of restrictions), are not comparable. In humans, one study recently showed that muscle protein synthesis was decreased after moderate energy restriction. 12 Other data have been obtained in rats and revealed contrasting effects of energy restriction on muscle protein anabolism, depending the type of muscle (soleus