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-phenylalanine, on gut motility, gut hormone release, blood glucose control and energy intake in humans. We hypothesise that L-phenylalanine 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
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-phenylalanine on gut motility, gut hormone release
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-phenylalanine on gut motility, gut hormone release, blood glucose control and energy intake in humans. We hypothesise that L-phenylalanine, 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-phenylalanine at 0.2 kcal/min (4.4 g/90 min), (ii), L-phenylalanine at 0.4 kcal/min (8.8 g/90 min) or (iii) 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 3 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
15 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
Male and female (BMI 18 to 25 kg/m2) subjects, aged between 18 to 50 years, will be included in the study. All subjects will be required to be weight-stable (ie less than 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.) Lactose intolerance/other food allergy, diabetes mellitus, as defined by fasting glucose higher than 6.9 mmol/l and/or glycated haemoglobin higher than 6.2 %, epilepsy, cardiovascular or respiratory diseases, current intake of more than 2 standard drinks on more than 5 days per week, current smokers of cigarettes/cigars/marijuana, restrained eaters (score more than 12 on the three factor eating questionnaire), vegetarians, in female subjects, pregnancy or lactation. Phenylketonuria (PKU) ie missing the enzyme phenylalanine hydroxylase, which is needed to break down phenylalanine.
Outcome results
None listed