Effects of branched amino acids supplementation in malnourished elderly with catabolic status.
ABSTRACT Among various nutrients branched amino acids (BCAAS) have been shown to be the most responsible for the stimulation of protein synthesis in various situations including catabolic states.
We evaluated the effect of a small amount of proteins enriched with BCAAs (0.4 g/kg/day and 0.2 g/kg/day BCAAs) on body weight and composition; nitrogen balance, energy intake and inflammation after 2 weeks of supplementation in acute elderly with catabolic status.
Two weeks randomized controlled trial.
Geriatric department of teaching hospital.
Thirty patients with malnutrition and inflammatory process (MNA < 24, albumin < 30 g/l and CRP > or = 20 mg/l) who agreed to participate in the study were consecutively included.
Body composition was determined by labelled water dilution method; resting energy expenditure (REE) was determined by indirect calorimetry; energy intake was calculated for a 3 days period at D1 and D12. Nutritional and inflammatory proteins and cytokines (IL-6 and TNF) were measured at day 1 and 14.
No difference was observed at day 14 between supplemented (S) and control (C) group for weight (S: 58.0 +/- 11.8 kg and C: 60.0 +/- 15.9 kg); fat free mass (S: 40.7 +/- 8.3 kg and C: 40 +/- 8.2 kg); nitrogen balance (S: 1.34 +/- 2.21 g/day and C: 0.59 +/- 4.47 g/day); and energy intake (S: 20 +/- 3.6 kcal/day and C: 20.5 +/- 8.6 kcal/day). Energy intake was at similar level than REE and clearly less than energy requirement in C and S. A significant decrease was observed for orosomucoid and Prognostic Inflammatory and Nutritional Index (PINI) in S.
Our results do not confirm improvement of nutritional status with enriched BCAAs supplementation as suggested in the literature. Persistence of inflammatory condition may be an explanation despite an improvement of inflammatory status was observed in the supplemented group. Those results show clearly that energy requirements are not covered in acute hospitalized elderly people. The fact that not only energy intake but also REE are decreased brings a new insight on catabolic situations.
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ABSTRACT: The nature of the deficit underlying age-related muscle wasting remains controversial. To test whether it could be due to a poor anabolic response to dietary amino acids, we measured the rates of myofibrillar and sarcoplasmic muscle protein synthesis (MPS) in 44 healthy young and old men, of similar body build, after ingesting different amounts of essential amino acids (EAA). Basal rates of MPS were indistinguishable, but the elderly showed less anabolic sensitivity and responsiveness of MPS to EAA, possibly due to decreased intramuscular expression, and activation (phosphorylation) after EAA, of amino acid sensing/signaling proteins (mammalian target of rapamycin, mTOR; p70 S6 kinase, or p70(S6k); eukaryotic initiation factor [eIF]4BP-1; and eIF2B). The effects were independent of insulin signaling since plasma insulin was clamped at basal values. Associated with the anabolic deficits were marked increases in NFkappaB, the inflammation-associated transcription factor. These results demonstrate first, EAA stimulate MPS independently of increased insulin availability; second, in the elderly, a deficit in MPS in the basal state is unlikely; and third, the decreased sensitivity and responsiveness of MPS to EAA, associated with decrements in the expression and activation of components of anabolic signaling pathways, are probably major contributors to the failure of muscle maintenance in the elderly. Countermeasures to maximize muscle maintenance should target these deficits.Faseb J. 01/2004; 19(3):422-4.
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ABSTRACT: To test the hypothesis that muscle protein synthesis (MPS) is regulated by the concentration of extracellular amino acids, we investigated the dose-response relationship between the rate of human MPS and the concentrations of blood and intramuscular amino acids. We increased blood mixed amino acid concentrations by up to 240 % above basal levels by infusion of mixed amino acids (Aminosyn 15, 44-261 mg kg-1 h-1) in 21 healthy subjects, (11 men 10 women, aged 29 +/- 2 years) and measured the rate of incorporation of D5-phenylalanine or D3-leucine into muscle protein and blood and intramuscular amino acid concentrations. The relationship between the fold increase in MPS and blood essential amino acid concentration ([EAA], mM) was hyperbolic and fitted the equation MPS = (2.68 x [EAA])/(1.51 + [EAA]) (P < 0.01). The pattern of stimulation of myofibrillar, sarcoplasmic and mitochondrial protein was similar. There was no clear relationship between the rate of MPS and the concentration of intramuscular EAAs; indeed, when MPS was increasing most rapidly, the concentration of intramuscular EAAs was below basal levels. We conclude that the rates of synthesis of all classes of muscle proteins are acutely regulated by the blood [EAA] over their normal diurnal range, but become saturated at high concentrations. We propose that the stimulation of protein synthesis depends on the sensing of the concentration of extracellular, rather than intramuscular EAAs.The Journal of Physiology 10/2003; 552(Pt 1):315-24. · 4.38 Impact Factor
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ABSTRACT: This review collates studies of healthy, sick, underweight (BMI < or = 21 kg/m2) and very elderly people (> or = 90 yr), in whom resting energy expenditure (REE) was measured using indirect calorimetry. We have observed the following: (1) REE, when adjusted for differences in both body weight and fat-free mass (FFM), is similar in healthy and in sick elderly people being 20 and 28 kcal/kg of FFM per day, respectively, (2) their nutritional status influences their energy requirements given that weight-adjusted REE increases in line with a decrease in BMI, (3) total energy expenditure is lower in sick elderly people given that their physical activity level, i.e. the ratio of total energy expenditure to REE, is reduced during disease averaging at 1.36, (4) energy intake (EI) being only 1.23 x REE is insufficient to cover energy requirements in sick elderly patients, whereas the EI of healthy elderly people appears sufficient to cover requirements, and finally, (5) gender ceases to be a determinant of REE in people aged 60 yr or over, with the Harris & Benedict equation capable of accurately predicting mean REE in this population, whether healthy or sick.Clinical Nutrition 03/2007; 26(1):16-24. · 3.30 Impact Factor