Marginal protein intake results in reduced plasma IGF-I levels and skeletal muscle fiber atrophy in elderly women

J Nutr Health Aging. 2000;4(2):85-90.


We investigated the effects of dietary protein on plasma IGF-I levels and muscle fiber cross-sectional area (CSA). Twelve healthy elderly women were randomly assigned to a weight-maintaining diet containing either 1.47 (marginal) or 2.94 (adequate) g protein/kg body cell mass (BCM)/d, (0.45 and 0.92 g/kg body weight/d, respectively) for 10wks. Plasma IGF-I levels and muscle fiber areas and distributions were evaluated at baseline and 10wks. After 10wks, both IGF-I and type I fiber CSA had declined significantly in subjects fed the marginal diet (30.1+/-2.1% and 32.7+/-7.9%, respectively) while they increased in those fed the adequate diet (19.5+/-7.0% and 22.3+/-7.5%, for IGF-I and type I CSA, respectively). The change in IGF-I was the only significantly associated with the change in type I fiber CSA (r2=0.70; p<0.03). These findings show that marginal dietary protein intakes will result in losses of muscle mass in the elderly and suggest a role for plasma IGF-I as a biochemical marker for the histological changes in skeletal muscle.

Publication types

  • Clinical Trial
  • Controlled Clinical Trial

MeSH terms

  • Aged
  • Aging / physiology*
  • Biomarkers / blood
  • Body Composition
  • Diet, Protein-Restricted / adverse effects*
  • Dietary Proteins / administration & dosage*
  • Female
  • Humans
  • Insulin-Like Growth Factor I / analysis*
  • Longitudinal Studies
  • Muscle Fibers, Skeletal / pathology
  • Muscle, Skeletal / pathology*
  • Muscular Atrophy / diagnosis
  • Muscular Atrophy / etiology*
  • Nitrogen / metabolism


  • Biomarkers
  • Dietary Proteins
  • Insulin-Like Growth Factor I
  • Nitrogen