title: Attenuation of the protein wasting associated with bed rest by branched-chain amino acids.
abstract: Bed rest is generally accepted as being an appropriate ground-based model for human spaceflight. The objectives of this study were to test the hypothesis that increasing the amount of branched-chain amino acids (BCAAs) in the diet could attenuate the protein loss associated with bed rest. Nineteen healthy subjects were randomized into two groups according to diet. During the 6 d of bed rest, the diets were supplemented with either 30 mmol/d each of three non-essential amino acids, glycine, serine, and alanine (control group), or with 30 mmol/d each of the BCAAs, leucine, isoleucine, and valine (BCAA group). Nutrition was supplied as a commercially available defined formula diet at a rate of 1.3 x REE. Nitrogen (N) balance and urinary 3-MeH excretion were determined for the 6 d. In our results, the urine-based estimate of N balance was 22.2 +/- 14.4 (n = 9) mg N.kg-1.d-1 and 60.5 +/- 10.1 mg (n = 8) N.kg-1.d-1 for the control and BCAA-supplemented groups, respectively (P < 0.05). Urinary 3-MeH excretion was unchanged in both groups with bed rest. We conclude that BCAA supplementation attenuates the N loss during short-term bed rest.
authors.affiliation: Department of Surgery, University of Medicine and Dentistry of New Jersey, School of Osteopathic Medicine, Stratford 08084, USA.
authors.forename: T P
authors.initials: TP
authors.lastname: Stein
authors.forename: M D
authors.initials: MD
authors.lastname: Schluter
authors.forename: M J
authors.initials: MJ
authors.lastname: Leskiw
authors.forename: G
authors.initials: G
authors.lastname: Boden
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000378:metabolism; D000597:Amino Acids, Branched-Chain / Q000008:administration & dosage / Q000627:therapeutic use*; D001510:Bed Rest / Q000009:adverse effects*; D004734:Energy Metabolism; D005260:Female; D005526:Food, Formulated; D006801:Humans; D007532:Isoleucine / Q000008:administration & dosage; D007930:Leucine / Q000008:administration & dosage; D008297:Male; D008762:Methylhistidines / Q000652:urine; D009124:Muscle Proteins / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism; D014633:Valine / Q000008:administration & dosage; D019282:Wasting Syndrome / Q000178:diet therapy*
chemical_list: D000596:Amino Acids; D000597:Amino Acids, Branched-Chain; D008762:Methylhistidines; D009124:Muscle Proteins; D007532:Isoleucine; D007930:Leucine; D014633:Valine; C028118:3-methylhistidine; D009584:Nitrogen