Nitrogen balance in older individuals in energy balance depends on timing of protein intake.
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.
Jordan
Leora Y
LY
Department of Health and Exercise Science, Colorado State University, Fort Collins, CO 80523-1582, USA.
Melanson
Edward L
EL
Melby
Christopher L
CL
Hickey
Matthew S
MS
Miller
Benjamin F
BF
D000368:Aged; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000494:pharmacology; D004044:Dietary Proteins / Q000494:pharmacology*; D004734:Energy Metabolism / Q000502:physiology*; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009584:Nitrogen / Q000378:metabolism*; D009751:Nutritional Requirements; D013997:Time Factors
D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D009584:Nitrogen