None listed
Conditions
Brief summary
The ingestion of nutrients induces a number of changes in gastrointestinal 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 and changes in small intestinal motility. It has been established that fat and carbohydrate empty from the stomach at an overall rate of 1-3kcal/minute irrespective of volume, while the load of fat and carbohydrate is known to effect gastrointestinal motor activity and slow gastric emptying rate. To date, research documenting the gastric emptying rate of protein is limited and the effect of varying the protein load has not been characterised. Moreover, the relationship between gastric emptying and the regulation of energy intake by dietary protein remains unclear. Effects on gastrointestinal hormone release also occur with macronutrient ingestion. Small intestinal administration of fat has been shown to increase plasma CCK, PYY, and GLP-1 to a greater extent than carbohydrate in both healthy young and older men. However, evidence for load-dependent effects of protein on gut hormones is inconsistent. Since these gastrointestinal hormones have an important role in the regulation of appetite and energy intake, it is imperative that changes in the magnitude and temporal pattern of their release is established in response to varying protein loads and also related to changes in gastric emptying and intragastric meal distribution. Thus, this study has been designed to investigate how the load of orally administered Whey Protein Isolate effects gastric emptying rate, intragastric meal distribution, gut hormone concentrations, appetite sensations, and subsequent energy intake in healthy, lean individuals.
Interventions
The participant will receive a single 450mL preload per study visit (separated by at least 3 days) in a randomised, crossover fashion of: i) 30 grams Whey Protein Isolate with diet lime cordial flavouring ii) 70 grams Whey Protein Isolate with diet lime cordial flavouring or iii) Water control with diet lime cordial flavouring. All preloads contain measured amounts of saline solution to match the osmolarity of each drink, and 100uL of 13C Octanoic acid to enable measurement of gastric emptying v
The participant will receive a single 450mL preload per study visit (separated by at least 3 days) in a randomised, crossover fashion of: i) 30 grams Whey Protein Isolate with diet lime cordial flavouring ii) 70 grams Whey Protein Isolate with diet lime cordial flavouring or iii) Water control with diet lime cordial flavouring. All preloads contain measured amounts of saline solution to match the osmolarity of each drink, and 100uL of 13C Octanoic acid to enable measurement of gastric emptying via 13CO2 in the breath. Gastric emptying rate and intragastric meal distribution using 3D ultrasound, hormone concentrations by blood sampling, appetite sensation questionnaires in the form of a Visual Analogue Scale (VAS), and subsequent energy intake will be measured. A buffet meal will be provided at 180 mins following the preload and the participant will have 30 minutes to eat until comfortably full. The buffet meal consists of 300mL orange juice, 600mL water, 375mL iced coffee, 4 slices white bread, 4 slices brown bread, 100g deli leg ham, 100g virginian chicken, 4 slices cheese, 100g tomato, 100g cucumber, 100g lettuce, 2 portions mayonnaise, 2 portions margarine, 1 medium red delicious apple, 1 medium banana, 200g chocolate custard, 150g fruit salad, 200g strawberry yoghurt, and a 14g milky way chocolate bar. Each volunteer will receive one of each of the 3 treatments on each of the 3 study days. Each study visit will be separated by no less than 3 days. Each visit will last approximately 4 hours.
Sponsors
Dr Natalie Luscombe-Marsh
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Treatment
Masking
Blinded (masking used)
Eligibility
Sex/Gender
All
Age
18 Years to 55 Years
Healthy volunteers
Yes
Inclusion criteria
non-obese with a body mass index of 19-25kg/m2 and weight stable (<5% fluctuation in body weight in previous 3 months)
Exclusion criteria
1) Significant gastrointestinal symptoms; disease or surgery 2) Use of prescribed or non-prescribed medications (including vitamins and herbal supplements) which may effect energy metabolism, GI function, body weight or appetite (eg domperidone and cisapride, anticholinergic drugs (eg. atropine), metoclopramide, erythromycin, hyoscine, orlistate, green tea extracts, astragalus, St. johns Wort etc.) 3) Diabetes mellitus, epilepsy, cardiovascular or respiratory disease, or any other significant illness as assessed by the investigator 4) Intake of >20g alcohol on a daily basis 5) Smokers (cigarettes, cigars, marijuana) 6) In female subjects, pregnancy or lactation. A pregancy test will be performed in all female subjects of childbearing potential, using a urine sample, prior to commencement of the study and subsequently prior to each study day 7) Restrained eaters, as determined by a score of >12 on the eating restraint questionnaire component of the 3 factor eating questionnaire 8) Donation of blood in the past 12 weeks prior to enrolment in the study. Subjects will also be advised to abstain from donating blood for 12 weeks following study completion 9) Consumption of a vegetarian diet.
Outcome results
None listed