Journal Articles

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Author: search.filters.author.Giezenaar CSubject: search.filters.subject.11 Medical and Health Sciences

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    Effects of intraduodenal protein on appetite, energy intake, and antropyloroduodenal motility in healthy older compared with young men in a randomized trial.
    (2014-10) Soenen S; Giezenaar C; Hutchison AT; Horowitz M; Chapman I; Luscombe-Marsh ND
    BACKGROUND: Protein-rich supplements are used widely for the prevention and management of undernutrition in older people. The use of protein supplements in older people could, however, be counterproductive by reducing appetite and overall energy intake. OBJECTIVE: The objective was to determine whether aging influences the effects of protein loads, administered directly into the small intestine, on energy intake, antropyloroduodenal motility, and appetite. DESIGN: Intraduodenal infusions (240 mL, 60 min) of saline (0 kcal, control) and protein (hydrolyzed whey) loads of 30, 90, and 180 kcal were followed by an ad libitum buffet meal in 10 young (19-29 y) and 10 healthy older (68-81 y) men. Suppression of energy intake (kcal) at the meal by protein infusion compared with control was calculated. RESULTS: In young subjects, a dose-responsive suppression (±SEM) of energy intake was found at the buffet meal by protein (suppression at 30 kcal: 7 ± 8%, P = 0.189; 90 kcal: 17 ± 8%, P = 0.054; 180 kcal: 33 ± 7%, P = 0.002), whereas suppression was observed only after the 180-kcal load in older subjects (30 kcal: 7 ± 4% increase, P = 0.126; 90 kcal: 6 ± 7% increase, P = 0.291; 180 kcal: 17 ± 6% suppression, P = 0.016). Suppression of energy intake by protein was less in older than in young subjects (P < 0.005). In young subjects, total energy intake (meal + infusion) on the 180-kcal protein-infusion day was lower than that on the control day (P = 0.041), whereas in older subjects it was greater on the 30-kcal (P = 0.033) and 90-kcal (P = 0.016) infusion days. Energy intake was inversely related to isolated pyloric pressure waves (r = -0.32, P = 0.013) and positively related to antral (r = 0.30, P = 0.021) and duodenal (r = 0.35, P = 0.006) pressure waves. Suppression of energy intake by protein was inversely related to the change in isolated pyloric pressure waves (r = -0.35, P = 0.027) and positively related to duodenal pressure waves (r = 0.32, P = 0.044). CONCLUSIONS: Intraduodenal protein suppresses appetite and energy intake less in healthy older than in young adults. In older subjects, intraduodenal protein at low doses increased overall energy intake, which supports the use of protein supplements in undernourished older people. This trial was registered at www.anzctr.org.au as 12612000906853.
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    Effects of age on blood pressure and heart rate responses to whey protein in younger and older men
    (John Wiley and Sons, Inc on behalf of The American Geriatrics Society, 2021-05) Giezenaar C; Oberoi A; Jones KL; Horowitz M; Chapman I; Soenen S
    BACKGROUND: Postprandial falls in blood pressure (BP) are more common in older compared to younger individuals. The effects of protein compared to carbohydrates and fat on postprandial BP, and the relation to gastric emptying rates, are poorly studied. OBJECTIVES: To determine the effects of a whey protein compared to a control drink on systolic BP (SBP) and diastolic BP (DBP), and heart rate (HR) in healthy younger and older men, and to relate these effects to gastric emptying. DESIGN: A pooled analyses of two randomized, double-blind, cross-over studies. SETTING: Two acute clinical intervention studies with identical study design. PARTICIPANTS: Nineteen older (age: 74 ± 1 years, body mass index: 26 ± 1 kg/m2 ) and 13 younger (23 ± 1 years, 24 ± 1 kg/m2 ) healthy men. INTERVENTION: A 70 g/280 kcal whey-protein or control (water with diet cordial, ~2 kcal) drink (450 ml). MEASUREMENTS: BP and HR were assessed with an automated device immediately before and at 3-min intervals after drink ingestion (0-180 min). Gastric emptying of the drinks was measured using 3D ultrasonography (0-180 min). RESULTS: Older versus younger men exhibited a greater fall in SBP (-23 ± 2 vs -15 ± 2 mmHg, p = 0.001) after whey-protein versus control, as BP did not change after the two drinks in younger men (p > 0.05). The nadir in SBP occurred later in the older than younger men (114 ± 11 vs 62 ± 14 min; p < 0.001), with SBP still apparently declining 180 min after whey-protein ingestion in the older men. The magnitude of the rise in HR was greater (p < 0.05) in the younger than older men. CONCLUSION: Following ingestion of 70 g whey protein, healthy older men exhibited a sustained fall in BP, despite an increase in HR, whereas in younger men there was no change in BP. BP may need to be monitored after high protein meals in older people at risk of postprandial hypotension.
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    Effects of randomized whey-protein loads on energy intake, appetite, gastric emptying, and plasma gut-hormone concentrations in older men and women.
    (2017-09) Giezenaar C; Trahair LG; Luscombe-Marsh ND; Hausken T; Standfield S; Jones KL; Lange K; Horowitz M; Chapman I; Soenen S
    Background: Protein- and energy-rich supplements are used widely for the management of malnutrition in the elderly. Information about the effects of protein on energy intake and related gastrointestinal mechanisms and whether these differ between men and women is limited.Objective: We determined the effects of whey protein on energy intake, appetite, gastric emptying, and gut hormones in healthy older men and women.Design: Eight older women and 8 older men [mean ± SEM age: 72 ± 1 y; body mass index (in kg/m2): 25 ± 1] were studied on 3 occasions in which they received protein loads of 30 g (120 kcal) or 70 g (280 kcal) or a flavored water control drink (0 kcal). At regular intervals over 180 min, appetite (visual analog scales), gastric emptying (3-dimensional ultrasonography), and blood glucose and plasma gut-hormone concentrations [insulin, glucagon, ghrelin, cholecystokinin, gastric inhibitory polypeptide (GIP), glucagon-like peptide 1 (GLP-1), and peptide tyrosine tyrosine (PYY)] were measured, and ad libitum energy intake was quantified from a buffet meal (180-210 min; energy intake, appetite, and gastric emptying in the men have been published previously).Results: Energy intake at the buffet meal was ∼80% higher in older men than in older women (P < 0.001). Energy intake was not suppressed by protein compared with the control in men or women (P > 0.05). There was no effect of sex on gastric emptying, appetite, gastrointestinal symptoms, glucose, or gut hormones (P > 0.05). There was a protein load-dependent slowing of gastric emptying, an increase in concentrations of insulin, glucagon, cholecystokinin, GIP, GLP-1, and PYY, and an increase in total energy intake (drink plus meal: 12% increase with 30 g and 32% increase with 70 g; P < 0.001). Energy intake at the buffet meal was inversely related to the stomach volume and area under the curve of hormone concentrations (P < 0.05).Conclusion: In older men and women, whey-protein drinks load-dependently slow gastric emptying and alter gut hormone secretion compared with a control but have no suppressive effect on subsequent ad libitum energy intake. This trial was registered at www.anzctr.org.au as ACTRN12612000941864.