effects of inulin and arabinoxylan on satiety, energy/food intake and changes in the human gut microbiota

Conditions: Overweight and Obesity

Summary: this proposed randomized, double blinded 12 week crossover human feeding study aims to investigate the effects of consuming a composite drink of inulin and arabinoxylan on satiety by measuring appetite biomarkers such as subjective satiety, energy/food intake and changes in the human gut microbiota in healthy weight males (22 to 24.9kg/m2)

research that focuses on the mechanisms involved in appetite regulation is topical given the emergence of the worldwide obesity epidemic. understanding the physiological processes associated with the onset of obesity is essential for the development of effective anti-obesity strategies. there is evidence that people who consume a diet high in non-starch polysaccharides (nsps) have a lower body mass index (bmi) than those that do not. a 2009 review of fibre and satiety by bridget benelam, 2009 focused on different types of fibre and the significant impact they may have on satiety and/or energy intake, through fermentation of fibre such as non starch polysaccharides in the colon by gut bacterial groups such as bifidobacterium. non starch polysaccharides and other fibre sources are poorly digested by human enzymes in the small intestine but are degraded by large groups of bacteria in the large bowel. one of the beneficial outcomes of this fermentation of fibre that gut bacteria produce of metabolites called short chain fatty acids (scfa) thought to affect appetite regulation by stimulating production of satiety hormones that can help you feel full. acetate and propionate are two of these metabolites highlighted as potential mediator of satiety. some fibres are called prebiotics as they act as selective sources for beneficial gut bacteria. however western populations do not consume natural prebiotics in high quantities in their diet and the overall intake of fibre is also low. therefore, in this study, the investigators aim to utilise a mixture of prebiotics in order to increase the growth and/or activity of commensal gut bacteria and scfa production in human volunteers and to assess the effects of consumption on satiety. testing the impact of a composite mix of inulin and arabinoxylan in a human study will help determine the effect it has on appetite regulation, ad libitum food intake, scfa production, anthropometric measurements, cognitive state (e.g. mood) and composition of the gut microbiota. the study design is a 12 week randomized, human feeding study, with a crossover design testing a composite mix of inulin and arabinoxylan against an equivalent energy matched (kcal) maltodextrin control drink in 33 healthy weight (22 to 24.9kg/m2) males aged between 21-55. volunteers will be enrolled to treatment or placebo for four weeks, with a four week wash out before the crossover. the primary endpoint, satiety following a test meal challenge will be measured on four occasions throughout the study. anthropometry measures, dietary intake, body weight and blood pressure will be monitored throughout the study. faecal and urine will be collected at baseline and at the end of each treatment period.

Eligibility criteria:
inclusion criteria: * males * 21-55 years old * body mass index (bmi) 19.5-24.5kg/m2 * overall healthy * weight stable (\<3 kg change in the past 4 months, before the trial). exclusion criteria: * smokers * drink more than 28 units of alcohol per week (i.e. not more than 14 pints of beer or 28 small glasses of wine) * restricted diet such as weight loss, vegetarian/vegan or taking dietary supplements such as prebiotics (such as oligosaccharides ie fructo-oligosaccharides (fos), galacto-oligosaccharides (gos) or probiotics (ie actimel)), not eating breakfast and \>25g/d dietary fibre consumption as well as those with food allergies * gastrointestinal procedure or surgery in the past three months. * gastrointestinal disorders: celiac disease, intestinal bowel disease (ibd), irritable bowel syndrome (ibs), chronic constipation, diverticulitis or a history of chronic constipation, diarrhoea, or other chronic gastrointestinal complaints * disorders of swallowing, severe dysphagia to food or pills. * appetite modulator drugs: orlistat, sibutramine, rimonabant. * mood disorder medications: antidepressants, lithium. * chronic metabolic conditions: diabetes, hepatic disease, gout, kidney, thyroid or coagulation disease. * psychiatric disorder: severe depression, bulimia, anorexia, schizophrenia, bipolar disorder. * pregnancy * others: oral antidiabetics, insulin, digoxin, thyroid hormones, antibiotics, steroids or immunosuppressants, recreational substances. * use of implanted or portable electro-mechanical device such as cardiac peacemaker or infusion pump. * blood donor in the past 3 months.