Research Study Abstract

Nitrogen Balance in Older Individuals in Energy Balance Depends on Timing of Protein Intake

  • Published on Oct. 2010

Abstract: To explore whether nitrogen retention can differ on an isonitrogenous diet by changing when protein is consumed, we performed a short-term study in older individuals (64.5 ± 2.0 years) performing daily exercise while in energy balance. Participants consumed an isonitrogenous–isocaloric diet with the timing of a protein or carbohydrate beverage after exercise (protein after exercise [PRO], carbohydrate after exercise [CHO]) versus earlier in the day. Three-day mean energy balance (PRO: 202 ± 36 kcal and CHO: 191 ± 44 kcal; p = .68) did not differ between trials, but 3-day mean nitrogen balance was significantly more positive in the PRO (1.2 ± 0.32 g N) trial than the CHO trial (0.8 ± 0.45 g N; p < .05). Older individuals were better able to maintain nitrogen balance by simply changing when a portion of an identical amount of daily protein was consumed.


  • Leora Y. Jordan 1
  • Edward L. Melanson 2
  • Christopher L. Melby 3
  • Matthew S. Hickey 1
  • Benjamin F. Miller 1


  • 1

    Department of Health and Exercise Science, Colorado State University, Fort Collins

  • 2

    Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Denver School of Medicine, Aurora

  • 3

    Department of Food Science and Human Nutrition, Colorado State University, Fort Collins


J Gerontol A Biol Sci Med Sci