Short-term protein and energy supplementation activates nitrogen kinetics and accretion in poorly nourished elderly subjects.
BACKGROUND
An increase in protein intake exerts a stimulating effect on protein kinetics in children, young adults, and healthy elderly persons. However, there are few data on the response to such dietary changes in malnourished elderly subjects, despite important medical implications in this population.


OBJECTIVE
The objective of this study was to determine the metabolic response to short-term nutritional supplementation in moderately malnourished elderly subjects.


METHODS
The influence of 10 d of supplementation (1.67 MJ/d and 30 g protein/d) on body composition, resting energy expenditure, and whole-body protein kinetics was studied in 17 malnourished elderly patients and 12 healthy young adults. A control group of 6 malnourished elderly patients received no supplementation.


RESULTS
Supplemented elderly subjects had a significantly greater fat-free mass gain than did unsupplemented elderly subjects (1.3 and 0.1 kg, respectively; age effect, P < 0.05; diet effect, P < 0.02) and a significantly greater increase in fasting rate of protein synthesis than did young supplemented subjects (0.6 and 0.2 g*kg FFM(-1)*11 h(-1); age effect, P < 0.05). The net protein balance in the supplemented elderly subjects in the fed state was positively correlated with protein intake (r(2) = 0.46) and in the fasted state was negatively correlated with protein intake (r(2) = 0.27). The sum of these regressions is a line with increasingly positive net diurnal protein balance produced by increasing protein intake.


CONCLUSIONS
These data provide evidence of a short-term anabolic response of protein metabolism to dietary supplementation in malnourished elderly patients that is likely to improve muscle strength and functional status.
Bos
C
C
Institut National de la Recherche Agronomique (INRA), Unité de Nutrition Humaine et de Physiologie Intestinale, Institut National Agronomique Paris-Grignon (INA PG), Paris, France. bos@inapg.inra.fr
Benamouzig
R
R
Bruhat
A
A
Roux
C
C
Mahé
S
S
Valensi
P
P
Gaudichon
C
C
Ferrière
F
F
Rautureau
J
J
Tomé
D
D
D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000641:Ammonia / Q000097:blood / Q000652:urine; D001823:Body Composition / Q000502:physiology; D001834:Body Water / Q000502:physiology; D004044:Dietary Proteins / Q000378:metabolism*; D002149:Energy Intake / Q000502:physiology*; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D009584:Nitrogen / Q000097:blood / Q000378:metabolism* / Q000652:urine; D011502:Protein-Energy Malnutrition / Q000178:diet therapy* / Q000378:metabolism / Q000503:physiopathology; D014508:Urea / Q000097:blood / Q000652:urine; D015431:Weight Loss
D004044:Dietary Proteins; D000641:Ammonia; D014508:Urea; D009584:Nitrogen