EAA supplementation to increase nitrogen intake improves muscle function during bed rest in the elderly

Clin Nutr. 2010 Feb;29(1):18-23. doi: 10.1016/j.clnu.2009.03.009. Epub 2009 May 5.


Background & aims: Older individuals are more likely to experience extended hospitalization and become protein malnourished during hospitalization. The concomitant compulsory inactivity results in functional decline. Increasing protein intake in hospitalized patients improves nitrogen balance, but effects on function are unknown. In the present study, we examined the effects of increasing protein intake by essential amino acid (EAA) supplementation in older individuals subjected to 10 d bed rest on LBM and muscle function.

Methods: Subjects were given a placebo (n=12, 68+/-5 (SD) yrs, 83+/-19 kg) or 15 g of EAA (n=10, 71+/-6, 72+/-8 kg) 3 times per day throughout 10d of bed rest. LBM, muscle protein synthesis, and muscle function were determined before and after bed rest. Due to an imbalance in randomized gender distribution between groups, gender and beginning functional and LBM measures were utilized for analyses by repeated measures analysis of covariance (RMANCOVA).

Results: Analyses revealed the potential for the preservation of functional outcomes with EAA supplementation.

Conclusions: Increasing protein intake above the RDA may preserve muscle function in the elderly during compulsory inactivity. EAA supplementation is potentially an efficient method of increasing protein intake without affecting satiety.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Absorptiometry, Photon
  • Aged / physiology*
  • Aging
  • Amino Acids, Essential / administration & dosage
  • Amino Acids, Essential / therapeutic use*
  • Analysis of Variance
  • Bed Rest*
  • Body Composition / drug effects
  • Dietary Supplements*
  • Female
  • Hospitalization
  • Humans
  • Male
  • Muscle Proteins / biosynthesis
  • Muscle Proteins / drug effects
  • Muscle, Skeletal / drug effects*
  • Muscle, Skeletal / physiology*
  • Nitrogen / metabolism*
  • Protein-Energy Malnutrition / prevention & control


  • Amino Acids, Essential
  • Muscle Proteins
  • Nitrogen