Effect of dietary protein on bed-rest-related changes in whole-body-protein synthesis

• Published in: The American journal of clinical nutrition Vol. 52; no. 3; pp. 509 - 514
• Main Authors: Stuart, CA, Shangraw, RE, Peters, EJ, Wolfe, RR
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 01.09.1990; American Society for Clinical Nutrition
• Subjects: Adult; Bed Rest; Biological and medical sciences; CATABOLISME; CATABOLISMO; DIETA; dietary protein; Dietary Proteins; Dietary Proteins - pharmacology; Fundamental and applied biological sciences. Psychology; Glucose Clamp Technique; HOMBRES; HOMME; Humans; Insulin; Insulin - pharmacology; Kinetics; LEUCINA; LEUCINE; Leucine - metabolism; Male; men; metabolism; METABOLISME DE L'AZOTE; METABOLISMO DEL NITROGENO; Metabolisms and neurohumoral controls; Nitrogen; Nitrogen - metabolism; nitrogen balance; Nitrogen metabolism. Proteins. Glycoproteins. Nucleic acids. Collagen; Oxidation-Reduction; pharmacology; Protein Biosynthesis; Protein Deficiency; Protein Deficiency - metabolism; PROTEINAS; PROTEINE; REGIME ALIMENTAIRE; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Human; Proteins; Synthesis; Diet; Catabolism; Leucine; Bed rest
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/52.3.509

To determine whether increasing dietary protein could exert a beneficial effect on bed-rest-related protein catabolism, two groups of normal subjects were subjected to 7 d of bed rest while taking isocaloric diets containing either 0.6 or 1.0 g protein.kg body wt−1.d−1. Whole-body-leucine turnover, leucine oxidation, and nonoxidative leucine disappearance were measured by use of a constant infusion of 1-13C-leucine. Before bed rest, the higher-protein diet resulted in a 14% decrease in whole-body-leucine turnover and a 28% decrease in leucine oxidation, but net nonoxidative leucine disappearance was not different on the two diets. A 24% decrease in nonoxidative leucine disappearance was seen in subjects assigned to the lower-protein diet, who had been on bed rest, but on the higher-protein diet, leucine kinetics were unchanged by bed rest. Bed rest does not cause an increase in whole-body-protein breakdown, but decreased whole-body-protein synthesis is demonstrable when dietary protein is low. This decrease is prevented by a higher dietary amount of protein.