Research Articles

Branched Chain Amino Acids (BCAA’s)

 Branched chain amino acid supplementation during bed rest: Effect on recovery.

Stein TP, Donaldson MR, Leskiw MJ, Schluter MD, Baggett DW, Boden G.

Department of Surgery, University of Medicine and Dentistry of New Jersey-School of Osteopathic Medicine, Stratford, NJ, USA.

Background: Bed rest is associated with a loss of protein from the weight bearing muscle. Objectives: To determine whether increasing the amount of the branched chain amino acids (BCAAs) in the diet during bed rest would improve the anabolic response after bed rest. Methods: The study was divided into three phases, a one day ambulatory period, fourteen days of bed rest period and a four day recovery period. Before starting the bed rest phase, the subjects (n=12) were randomized into two groups. Dietary intake (1.3 x Resting energy expenditure) was supplemented with either 30 mMol.d(-1) each of glycine (2.16 g d(-1)), serine (3.15 g d(-1)) and alanine (2.58 g d(-1)) and diet 2 (BCAA supplemented) with 30 mMol.d(-1) each of the three branched chain amino acids leucine (3.93 g d(-1)), isoleucine (3.93 g d(-1)) and valine (3.51 g d(-1). Protein and glucose kinetics were measured during each phase. Whole body protein synthesis (WBPSR) was determined with U-(15)N labeled algal amino acids, muscle (M-FSR) and plasma protein synthesis (fibrinogen, ceruloplasmin, complement C-3, transferrin and VLDL Apoprotein B-100, PP-FSR) with (2)H5 L-phenylalanine. Total glucose production (RaT) and gluconeogenesis from alanine (RaGng) were determined by with a combination of U-(13)C3 L-alanine and 6,6 (2)H2 glucose. Daily N balance and urinary 3-methyylhistidine excretion were determined for the bed rest and recovery phases. Results: N retention was greater with BCAA fed group during the second week of bed rest (56 +/- 6 vs 26 +/- 12 mg N. kg(-1).d(-1), p<0.05). WBPSR was reduced by ~20% during bed rest (NEAA, 3.39 +/- 0.10 vs 2.86 +/- 0.18 g prot. kg(-1).d(-1), p<0.05; BCAA 3.96 +/- 0.33 vs 2.89 +/- 0.27 g prot. kg(-1).d(-1), p<0.05). There was no effect of BCAA supplementation on either M-FSR (0.34 +/- 0.15 vs 0.34 +/- 0.08 %. d(-1)), or PP-FSR or the rate of 3-MeH excretion (3.55 +/- 0.10 vs 3.26 +/- 0.10 micro mol.kg(-1).d(-1)) during or after bed rest. Muscle tissue free amino acid concentrations were increased during bed rest with BCAA (0.214 +/- 0.066 vs 0.088 +/- 0.12 nmol. mg protein(-1), p<0.05). RaT and RaAGng were unchanged with bed rest but were reduced (p<0.05) with the BCAA group in the recovery phase (RaT 22.2 +/- 1.0 vs 18.6 +/- 0.9 mmol. kg(-1).hr(-1) and RaT (0.72 +/- 0.10 vs 0.34 +/- 0.12 mmol. kg(-1).hr(-1)). Conclusions: Accretion of amino acids in the tissue free amino acid pools is a significant factor in the improved N balance found with BCAA supplementation during bed rest. The amount accreted is not enough to impact protein kinetics in the recovery phase, but does improve N retention by providing additional essential amino acids in the early recovery phase.

Branched-chain amino acids prolong exercise during heat stress in men and women.

Mittleman KD, Ricci MR, Bailey SP.

Department of Exercise Science, Rutgers University, New Brunswick, NJ 08903, USA. dwrite!kmittle@attmail.com

To assess the effect of branched-chain amino acids (BCAA) supplementation on endurance performance in the heat, six women and seven men participated in two trials of rest in the heat (Ta = 34.4 +/- 1.8 degrees C; rh = 39 +/- 14%), followed by 40% VO2peak exercise to exhaustion. Subjects ingested 5 mL x kg(-1) of a placebo (PLAC) or BCAA drink every 30 min. Cycle time to exhaustion increased during BCAA (153.1 +/- 13.3 vs 137.0 +/- 12.2 min, P < 0.05) for men and women. Plasma glucose was maintained at baseline values for both drinks; however, women had significantly higher concentrations (5.9 +/- 0.6 vs 4.0 +/- 0.2 mM, P < 0.05). Plasma free fatty acids and ammonia were not influenced by drink or gender but increased over time. BCAA resulted in a significant (P < 0.05) increase in plasma BCAA (1209 +/- 119 vs 496 +/- 44 microM), while F-TRP (9.6 +/- 0.9 vs 12.0 +/- 1.3 microM) and F-TRP:BCAA were decreased (0.009 +/- 0.001 vs 0.024 +/- 0.003 ND) in both men and women. Cardiovascular and thermoregulatory data were similar between treatments for all subjects. Psychological data were not influenced by BCAA. These results indicate BCAA supplementation prolongs moderate exercise performance in the heat.

http://jcem.endojournals.org/cgi/content/full/86/5/2136

Branched chain amino acids activate messenger ribonucleic acid translation regulatory proteins in human skeletal muscle, and glucocorticoids blunt this action.

Liu Z, Jahn LA, Long W, Fryburg DA, Wei L, Barrett EJ.

Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908, USA. zl3@virginia.edu

Branched chain amino acids (BCAA) are particularly effective anabolic agents. Recent in vitro studies suggest that amino acids, particularly leucine, activate a signaling pathway that enhances messenger ribonucleic acid translation and protein synthesis. The physiological relevance of these findings to normal human physiology is uncertain. We examined the effects of BCAA on the phosphorylation of eukaryotic initiation factor 4E-binding protein 1 (eIF4E-BP1) and ribosomal protein S6 kinase (p70(S6K)) in skeletal muscle of seven healthy volunteers. We simultaneously examined whether BCAA affect urinary nitrogen excretion and forearm skeletal muscle protein turnover and whether the catabolic action of glucocorticoids could be mediated in part by inhibition of the action of BCAA on the protein synthetic apparatus. BCAA infusion decreased urinary nitrogen excretion (P < 0.02), whole body phenylalanine flux (P < 0.02), plasma phenylalanine concentration (P < 0.001), and improved forearm phenylalanine balance (P = 0.03). BCAA also increased the phosphorylation of both eIF4E-BP1 (P < 0.02) and p70(S6K) (P < 0.03), consistent with an action to activate the protein synthetic apparatus. Dexamethasone increased plasma phenylalanine concentration (P < 0.001), prevented the BCAA-induced anabolic shift in forearm protein balance, and inhibited their action on the phosphorylation of p70(S6K). We conclude that in human skeletal muscle BCAA act directly as nutrient signals to activate messenger ribonucleic acid translation and potentiate protein synthesis. Glucocorticoids interfere with this action, and that may be part of the mechanism by which they promote net protein catabolism in muscle.

Mobilization of visceral adipose tissue related to the improvement in insulin sensitivity in response to physical training in NIDDM. Effects of branched-chain amino acid supplements.

Mourier A, Gautier JF, De Kerviler E, Bigard AX, Villette JM, Garnier JP, Duvallet A, Guezennec CY, Cathelineau G.

Service de Diabetologie et de Radiologie, Hopital Saint-Louis, Paris, France.

OBJECTIVE: To evaluate the effects of an intense physical training program on abdominal fat distribution, glycemic control, and insulin sensitivity in patients with NIDDM and to determine whether branched-chain amino acid (BCAA) supplements influence these effects. RESEARCH DESIGN AND METHODS: Twenty-four patients (ages 45 +/- 2 [mean +/- SE] years, BMI 30.2 +/- 0.9 kg/m2, HbA1c 7.9 +/- 0.3%) were randomly assigned to four groups: training plus BCAA supplement (n = 6), training plus placebo (n = 6), sedentary plus BCAA supplement (n = 6), and sedentary plus placebo (n = 6). Physical training consisted of a supervised 45-min cycling exercise at 75% of their oxygen uptake peak (VO2 peak) two times per week and an intermittent exercise one time per week for 2 months. RESULTS: Patients who exercised increased their VO2 peak by 41% and their insulin sensitivity by 46%. Physical training significantly decreased abdominal fat evaluated by magnetic resonance imaging (umbilicus), with a greater loss of visceral adipose tissue (VAT) (48%) in comparison with the loss of subcutaneous adipose tissue (18%), but did not significantly affect body weight. The change in visceral abdominal fat was associated with the improvement in insulin sensitivity (r = 0.84, P = 0.001). BCAA supplementation had no effect on abdominal fat and glucose metabolism. CONCLUSIONS: Physical training resulted in an improvement in insulin sensitivity with concomitant loss of VAT and should be included in the treatment program for patients with NIDDM.

Combined effects of caloric restriction and branched-chain amino acid supplementation on body composition and exercise performance in elite wrestlers.

Mourier A, Bigard AX, de Kerviler E, Roger B, Legrand H, Guezennec CY.

Centre d'Etudes et de Recherches de Medecine Aerospatiale, Departement de Physiologie Systemique, Bretigny-sur-orge, France.

Twenty-five competitive wrestlers restricted their caloric intake (28 kcal.kg-1.day-1) for 19 days, using a hypocaloric control (hC, n = 6), hypocaloric high-protein (hHP, n = 7), hypocaloric high-branched-chain amino acid (hBCAA, n = 6), hypocaloric low-protein (hLP, n = 6) diet to determine the effects of caloric restriction on body composition and performances versus control diet (C, n = 6). Anthropometric parameters (weight, percent body fat) and adipose tissue (AT) distribution measured by magnetic resonance imaging (MRI) obtained before and after diet, were compared. A significant highest body weight loss (-4 kg, p < 0.05) and decrease in the percent of body fat (-17.3%, p < 0.05) were observed for subjects of the hBCAA group. Subjects of the hBCAA group exhibited a significant reduction (-34.4%, p < 0.05) in abdominal visceral adipose tissue (VAT). There was no change in aerobic (VO2max) (p > 0.75) and anaerobic capacities (Wingate test) (p > 0.81), and in muscular strength (p > 0.82). We conclude that under our experimental conditions, the combination of moderate energy restriction and BCAA supplementation induced significant and preferential losses of VAT, and allowed maintainance of a high level of performance.

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