"Fast proteins" with a unique essential amino acid content as an optimal nutrition in the elderly: growing evidence.

Background & Aims: Adequate protein intake is crucial to maintain body protein content in elderly subjects, but quality of dietary proteins should be also considered since amino acid composition and rate of protein digestion modulate amino acid availability. This study investigates whether the efficacy of optimal protein intake levels for protein retention in the elderly is influenced by protein quality.

Methods: We investigated the effect of a 10-day adequate-protein (AP) or high-protein (HP) diet together with the protein source as caseins (CAS) or soluble milk proteins (PRO) on whole-body (WB) protein synthesis (PS) and protein breakdown (PB) in 4 groups of healthy elderly men (mean ± SEM: 71.

Effects of trans MUFA from dairy and industrial sources on muscle mitochondrial function and insulin sensitivity.

Epidemiological studies suggest that chronic consumption of trans MUFA may alter muscle insulin sensitivity. The major sources of dietary trans MUFA (dairy fat vs. industrially hydrogenated oils) have different isomeric profiles and thus probably different metabolic consequences.

Enhanced muscle mixed and mitochondrial protein synthesis rates after a high-fat or high-sucrose diet.

Objective: Obesity and insulin resistance are associated with muscle mitochondrial dysfunction, which might be related to impairment of mitochondrial protein synthesis. This study aimed at investigating mixed and mitochondrial protein synthesis in skeletal muscle in response to dietary manipulations.

Research Methods And Procedures: High-sucrose (SU) and high-fat, high-sucrose (F) diets were provided for 6 weeks to Wistar rats at standard (N) and high (H) energy intakes and compared with controls.

Chronological approach of diet-induced alterations in muscle mitochondrial functions in rats.

Objective: Mitochondrial dysfunction might predispose individuals to develop insulin resistance. Our objective was to determine whether mitochondrial dysfunction or insulin resistance was the primary event during high-fat (HF) diet.

Research Methods And Procedures: Rats were fed an HF diet for 0, 3, 6, 9, 14, 20, or 40 days and compared with control.

Synergistic effects of caloric restriction with maintained protein intake on skeletal muscle performance in 21-month-old rats: a mitochondria-mediated pathway.

Caloric restriction (CR) delays the onset of age-related mitochondrial abnormalities but does not prevent the decline in ATP production needed to sustain muscle protein fractional synthesis rate (FSR) and contractile activity. We hypothesized that improving mitochondrial activity and FSR using a CR diet with maintained protein intakes could enhance myofibrillar protein FSR and consequently improve muscle strength in aging rats. Wistar rats (21 months old) were fed either an ad libitum (AL), 40% protein-energy restricted (PER) or 40% AL-isonitrogenous energy restricted (ER) diet for 5 months.

Diets high in sugar, fat, and energy induce muscle type-specific adaptations in mitochondrial functions in rats.

Obesity is often associated with insulin resistance and mitochondrial dysfunction within skeletal muscles, but the causative factors are not clearly identified. The present study examined the role of nutrition, both qualitatively and quantitatively, in the induction of muscle mitochondrial defects. Two experimental diets [high sucrose (SU) and high fat (F)] were provided for 6 wk to male Wistar rats at 2 levels of energy [standard (N) and high (H)] and compared with a standard energy cornstarch-based diet (C).

Insulin regulates protein synthesis rate in leukocytes from young and elderly healthy humans.

Immune response is dependent on synthesis and secretion of various proteins. Hence, in vivo determination of protein synthesis rate in leukocytes may reflect the functional activity of these cells under conditions of immune deficiency such as aging. Because (i) insulin stimulates protein turnover in various tissues and (ii) elderly people often suffer from a decrease in insulin sensitivity, we sought to determine the effect of physiological hyperinsulinemia (0.

Higher calcium urinary loss induced by a calcium sulphate-rich mineral water intake than by milk in young women.

It is well known that the intestinal availability of Ca from Ca-rich mineral waters is equivalent to that of milk Ca. However, the effect of associated anions on Ca urinary loss needs to be addressed. The aim of the current study was to compare, under ordinary conditions of consumption, milk and a SO4-rich mineral water as the Ca provider in a large number of subjects consuming the same quantity of Ca from the two sources in a crossover study lasting for an extended period.

Whole body protein breakdown is less inhibited by insulin, but still responsive to amino acid, in nondiabetic elderly subjects.

Responses of whole body glucose disposal (GDR) and protein breakdown (PB) to physiological insulin levels are altered in nondiabetic elderly subjects. Amino acids enhance inhibition of PB by insulin in young subjects. We hypothesized that addition of amino acid to insulin may improve the defect in PB regulation by insulin in elderly people.

Mitochondrial and sarcoplasmic proteins, but not myosin heavy chain, are sensitive to leucine supplementation in old rat skeletal muscle.

Leucine has a major anabolic impact on muscle protein synthesis in young as in old animals. However, myosin heavy chain (MHC), sarcoplasmic and mitochondrial proteins may differently respond to anabolic factors, especially during aging. To test this hypothesis, fractional synthesis rates (FSR) of the three muscle protein fractions were measured using a flooding dose of [1-(13)C] phenylalanine, in gastrocnemius muscle of adult (8 months) and old (22 months) rats, either in postabsorptive state (PA), or 90-120 min after ingestion of a alanine-supplemented meal (PP+A) or a leucine-supplemented meal (PP+L).

Protein synthesis rates of human PBMC and PMN can be determined simultaneously in vivo by using small blood samples.

Immune cell functions can be evaluated in vivo by measuring their specific protein fractional synthesis rates (FSR). Using stable isotope dilution techniques, we describe a new method allowing simultaneous in vivo assessment of FSR in two leukocyte populations in healthy human subjects, using small blood samples. Peripheral blood mononuclear cell (PBMC) and polymorphonuclear neutrophil (PMN) FSR were measured during primed continuous intravenous infusion of l-[1-(13)C]leucine.

Human albumin synthesis is increased by an ultra-endurance trial.

Purpose: The purpose of this study was to determine whether an ultra-endurance event is a strong stimulus to increase albumin synthesis involved in the process of intravascular albumin mass increase associated with transient hypervolemia.

Methods: The albumin synthetic rate was measured in six young men, 3 d before (C) and on the 1st (R1) and 8th (R8) days of the recovery from an ultra-endurance trial (5 h daily for 4 d). Albumin fractional (FSR) and absolute (ASR) synthetic rate were determined using a primed-constant infusion of [1(-13) C] leucine.