None listed
Conditions
Brief summary
Regulation of the factors that control food intake, the function of the stomach and small intestine and release of gut hormones is complex, and our understanding of this field is far from complete. There is increasing evidence that nutrient stimuli in the gut, especially in the small intestine, induce changes in gut motor and hormonal functions that play a central role in the control of energy intake and blood glucose. In particular high-protein diets have been found to be very effective for weight loss and for improving blood glucose in obese with and without type 2 diabetes. This study aims to investigate the effects of the amino acid, L-tryptophan, on gut motility, gut hormone release, blood glucose control and energy intake in humans. We hypothesise that L-tryptophan as building block of proteins, may substantially contribute to the beneficial effects of whole protein on gut functions and energy intake regulation. This has not been evaluated in detail and will be important in order to enhance our understanding of the mechanisms underlying the effects of dietary protein on eating control.
Interventions
Regulation of the factors that control food intake, the function of the stomach and small intestine and release of gut hormones is complex, and our understanding of this field is far from complete. There is increasing evidence that nutrient stimuli in the gut, especially in the small intestine, induce changes in gut motor and hormonal functions that play a central role in the control of energy intake and blood glucose. In particular high-protein diets have been found to be very effective for wei
Regulation of the factors that control food intake, the function of the stomach and small intestine and release of gut hormones is complex, and our understanding of this field is far from complete. There is increasing evidence that nutrient stimuli in the gut, especially in the small intestine, induce changes in gut motor and hormonal functions that play a central role in the control of energy intake and blood glucose. In particular high-protein diets have been found to be very effective for weight loss and for improving blood glucose in obese with and without type 2 diabetes. This study aims to investigate the effects of the amino acid, L-tryptophan on gut motility, gut hormone release, blood glucose control and energy intake in humans. We hypothesise that L-tryptophan, as building block of proteins, may substantially contribute to the beneficial effects of whole protein on gut functions and energy intake regulation. A total of 20 Caucasian male and female (BMI 18-25 kg/m2) subjects, aged between 18 - 50 years, will be included in the study. Each subject will be studied on three occasions. On each occasion, they will receive, in randomized, double-blind fashion, a 90-min intraduodenal infusion of (i) L-tryptophan at 0.2 kcal/min, (ii), L-tryptophan at 0.4 kcal/min (iii) L-tryptophan at 0.6 kcal/min or (iv) saline (negative control). Gut motility, blood glucose, gut hormones release, insulin concentrations, appetite perceptions and energy intake during a buffet meal, as well as vital signs, will be measured. The buffet meal will be provided at the end of the infusion and the participant has 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 manyonnaise, 2 portions margarine, 1 medium apple, 1 medium banana, 200g chocolate custard, 150g fruit salad, 200g strawberry yoghurt, and 14g milky way chocolate bar. Each volunteer will receive one of each infusion solutions on each of the 4 study days. Each study visit will be separated by no less than 3 days.
Sponsors
Christine Feinle-Bisset
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Treatment
Masking
Blinded (masking used)
Eligibility
Sex/Gender
All
Age
18 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
Male and female (BMI 18-25 kg/m2) subjects, aged between 18 - 50 years, will be included in the study. All subjects will be required to be weight-stable (i.e. < 5 % fluctuation in their body weight) at study entry, as determined by their self-reported weight in the preceding 3 months, and will be required to maintain their normal physical activity over the course of the study.
Exclusion criteria
Significant gastrointestinal symptoms, disease or surgery, use of prescribed or non-prescribed medications (including vitamins and herbal supplements) which may affect energy metabolism, gastrointestinal function, body weight or appetite (eg domperidone, orlistat, green tea extracts, Astragalus, St Johns Wort etc.), as well as SSRIs (selective serotonin reuptake inhibitors), lactose intolerance/other food allergy, diabetes mellitus, as defined by fasting glucose >6.9 mmol/l and/or glycated haemoglobin =6.2 %, epilepsy, cardiovascular or respiratory diseases, current intake of > 2 standard drinks on > 5 days per week, current smokers of cigarettes/cigars/marijuana, restrained eaters (score > 12 on the three factor eating questionnaire), vegetarians, in female subjects, pregnancy or lactation.
Outcome results
None listed