None listed
Conditions
Brief summary
Ageing is associated with a physiological reduction of appetite and energy intake, which has been called the “anorexia of ageing”. Dietary supplementation with liquid protein preparations is now used frequently to increase energy and protein intake in older adults in both institutionalized and community-dwelling populations. Although the latter would appear a logical approach, evidence for success of increased energy intake in older individuals is limited. It is well established that the ingestion of nutrients induce a number of changes in gastrointestinal (GI) function, which are associated with the modulation of appetite and energy intake. These changes include the slowing of gastric emptying, which sustains gastric distension and is associated with proximal gastric relaxation. Urgent investigation is warranted to determine the optimal load of protein that can be incorporated into their diet to assist in sparing muscle mass without reducing their appetite. The study aims to characterise in healthy older individuals, absolute and in comparison to young individuals, the effect of different oral protein-rich loads on energy intake, appetite, antral area, gastric emptying, plasma concentrations of amino acids, hormones (i.e. CCK, PYY, ghrelin, GLP-1, GIP, glucagon and insulin) and glucose, and studies the relationship between the suppression of appetite and energy intake by protein with ‘intragastric’ mechanisms.
Interventions
A total of 15 healthy young (18-35 years) and 15 healthy older (>65 years) subjects with a body mass index (BMI) of 22-30 kg/m2 will be recruited. Each subject will be studied on 4 occasions, with a randomised intervention order, separated by at least 3 days. Bolus oral consumption of preloads containing the following amounts of calories and energy percentage (%) protein/carbohydrate/fat; i) control 0 kcal, ii) ‘pure protein’ 280 kcal and 100/0/0 energy % (70/0/0 g), or iii) ‘low-caloric protein
A total of 15 healthy young (18-35 years) and 15 healthy older (>65 years) subjects with a body mass index (BMI) of 22-30 kg/m2 will be recruited. Each subject will be studied on 4 occasions, with a randomised intervention order, separated by at least 3 days. Bolus oral consumption of preloads containing the following amounts of calories and energy percentage (%) protein/carbohydrate/fat; i) control 0 kcal, ii) ‘pure protein’ 280 kcal and 100/0/0 energy % (70/0/0 g), or iii) ‘low-caloric protein-rich’ 280 kcal 20/40/40 energy % (14/28/12.4 g); or iv) ‘high-caloric protein-rich’ 504 kcal 56/22/22 energy % (70/28/12.4 g). The drinks will be equivolaemic (~450 mL) and matched for taste, texture and appearance. The drinks will contain different quantities of food-grade whey protein isolate powder (Fonterra Australia Pty Ltd, Mt Waverley, Australia) dissolved in varying amounts of distilled water, sodium chloride and low-calorie lime cordial (Bickford’s ‘diet lime’ cordial). 0.1 g 13C sodium acetate will also be added to the nutrient-containing solutions to enable the measurement of gastric emptying through excretion of 13CO2 in the breath. Gastric emptying rate and intragastric meal distribution are determined using 3D ultrasound. Appetite sensation questionnaires in the form of a Visual Analogue Scale (VAS) are measured and blood samples are collected for concentrations of gut hormones, amino acids and glucose. A standard buffet meal is provided at 180 minutes following the preload and the participant has 30 minutes to eat until comfortably full. The weight of the foods will be recorded before and after it is offered to the subjects and energy intake and macronutrient composition calculated subsequently using commercially available software (Foodworks 3.01, Xyris Software, Highgate Hill, QLD, Australia).
Sponsors
Stijn Soenen
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Prevention
Masking
Blinded (masking used) (Subject, Caregiver, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
All
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
Body Mass Index (BMI): 22-30 kg/m2 Weight stable (<5% fluctuation in body weight in previous 3 months) Age young group: 18-35 years Age older group: >65
Exclusion criteria
Significant gastrointestinal symptoms, disease, or surgery. Current gallbladder or pancreatic disease; diabetes mellitus; epilepsy; cardiovasculr or respiratory diseases; any other illnesses as assessed by the investigator (including chronic illnesses not explicitly listed above). Impaired cognitive function. Depression. Use of prescribed or non-prescribed medications (including vitamins and herbal supplements) which may effect gastrointestinal function or appetite. Lactose intolerant or other food allergies; intolerance or allergy to paracetomol. Individuals with low ferritin levels or who have donated blood in the 12 weeks prior to taking part in the study. Current intake of >2 standard drinks on >5 days per week. Current smokers of cigarettes/cigars/marijuana. Current intake of any illicit substance. Experience claustrophobia in confined spaces. Unable to comprehend study protocol.
Outcome results
None listed