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

Am J Clin Nutr. 1990 Sep;52(3):509-14. 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.

Publication types

  • Clinical Trial
  • Controlled Clinical Trial
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Bed Rest*
  • Dietary Proteins / pharmacology*
  • Glucose Clamp Technique
  • Humans
  • Insulin / pharmacology
  • Kinetics
  • Leucine / metabolism
  • Male
  • Nitrogen / metabolism
  • Oxidation-Reduction
  • Protein Biosynthesis*
  • Protein Deficiency / metabolism


  • Dietary Proteins
  • Insulin
  • Leucine
  • Nitrogen