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Am J Physiol Regul Integr Comp Physiol. 2015 Oct 15;309(8):R845-54. doi: 10.1152/ajpregu.00213.2015. Epub 2015 Aug 19.

Lesser suppression of energy intake by orally ingested whey protein in healthy older men compared with young controls.

Author information

1
Discipline of Medicine and National Health and Medical Research Council of Australia, Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, South-Australia, Australia;
2
Discipline of Medicine and National Health and Medical Research Council of Australia, Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, South-Australia, Australia; Commonwealth Scientific and Industrial Research Organisation Animal, Food and Health Sciences, Adelaide, Australia; and.
3
Discipline of Medicine and National Health and Medical Research Council of Australia, Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, South-Australia, Australia; Department of Medicine, Haukeland University Hospital, Bergen, Norway.
4
Discipline of Medicine and National Health and Medical Research Council of Australia, Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, South-Australia, Australia; stijn.soenen@adelaide.edu.au.

Abstract

Protein-rich supplements are used widely for the management of malnutrition in young and older people. Protein is the most satiating of the macronutrients in young. It is not known how the effects of oral protein ingestion on energy intake, appetite, and gastric emptying are modified by age. The aim of the study was to determine the suppression of energy intake by protein compared with control and underlying gastric-emptying and appetite responses of oral whey protein drinks in eight healthy older men (69-80 yr) compared with eight young male controls (18-34 yr). Subjects were studied on three occasions to determine the effects of protein loads of 30 g/120 kcal and 70 g/280 kcal compared with a flavored water control-drink (0 g whey protein) on energy intake (ad libitum buffet-style meal), and gastric emptying (three-dimensional-ultrasonography) and appetite (0-180 min) in a randomized, double-blind, cross-over design. Energy intake was suppressed by the protein compared with control (P = 0.034). Suppression of energy intake by protein was less in older men (1 ± 5%) than in young controls (15 ± 2%; P = 0.008). Cumulative energy intake (meal+drink) on the protein drink days compared with the control day increased more in older (18 ± 6%) men than young (1 ± 3%) controls (P = 0.008). Gastric emptying of all three drinks was slower in older men (50% gastric-emptying time: 68 ± 5 min) than young controls (36 ± 5 min; P = 0.007). Appetite decreased in young, while it increased in older (P < 0.05). In summary, despite having slower gastric emptying, elderly men exhibited blunted protein-induced suppression of energy intake by whey protein compared with young controls, so that in the elderly men, protein ingestion increased overall energy intake more than in the young men.

KEYWORDS:

aging; appetite; energy intake; gastric emptying; whey protein

PMID:
26290103
PMCID:
PMC4666943
DOI:
10.1152/ajpregu.00213.2015
[Indexed for MEDLINE]
Free PMC Article

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