Clinical Research Directory

Soluble and Osmotic Fibre (SOLOS) Diet for Constipation

This research aims to study the dual effectiveness of incorporating soluble fibre and osmotic carbohydrates (SOLOS), with or without restricting fructans and GOS, and present novel findings in managing GI symptoms in patients with functional bowel disorders with constipation. These findings may also support researchers and clinicians in shaping new dietary approaches in the management of general constipation symptoms.

Aimmune Longitudinal Collaboration Study

This study will include healthy households around the Irvine, CA area (based local to employees) and Tempe, AZ and Philadelphia, PA sites that will be instructed to take a daily fiber supplement (2.5 tablespoons of chia seeds \[\~10.3g of fiber\] which is one serving) for two months. Participants will use a stool sampling tool to facilitate ease of stool collection, or they may donate at a study site. Half of participants will add chia seeds to their diet at the beginning of the study and then return to their baseline diet for the second half of the study; half of participants maintain their baseline diet for the first half of the study and add chia seeds to their diet at the second half of the study as a cross-over design. Households (or individual participants, if their household is not participating) will be chosen at random to decide who implements the intervention in the first half versus the second half of the study. Data measurement including metabolomics and sequencing of stool samples, blood sampling for biobanking, stool IgA analysis, stress and diet evaluations will occur initially and throughout the study. Lifestyle questionnaires including but not limited to diet surveys, stress, or depression screening may be collected through electronic forms or telephonically. During enrollment, participants may be asked to complete questionnaires focused on medical, family, dietary, and social histories. At the end of the study, donor microbiota samples from individuals that are IgA low (undetectable) throughout the study will be evaluated from the presence of microbes that can degrade IgA. If investigators find this is the case, investigators will screen for microbes that can degrade IgA. For individuals that show persistent high fecal IgA or show a substantial improvement in IgA, investigators will transplant fecal samples or spores from fecal samples into germ-free mice to further understand the microbiome and pathophysiology relationship. For the latter, the investigator's hypothesis is that fiber exposure of a specific type will reprogram the microbiome to stimulate IgA broadly to the entire microbiome as occurs with pectin derivative treated mice. The investigator's goal will be to isolate the microbes that respond to fiber to alter levels of IgA in the gut lumen.

Non-alcoholic, Fiber-enriched Beer and Its Effect on Blood Glucose Concentration

This study examines how various non-alcoholic beverages affect blood sugar levels. The beverages are a non-alcoholic, fiber-enriched beer, a conventional non-alcoholic beer, and a sugar solution. Participants drink one of these beverages on different days. Afterwards, a sensor on the upper arm is used to measure the sugar content in the body fluid under the skin over a period of two hours. The aim is to find out how much blood sugar concentration rises after drinking. This will be used to check whether the non-alcoholic, fiber-enriched beer has a more favorable effect on sugar metabolism than conventional beverages. Participation is voluntary, and the data will be treated confidentially.

The Effect of Pectin Supplementation on Geriatric With Frailty: A Randomised Placebo-Controlled Dietary Intervention Study

The study involves the intake of Low-methoxy (LM) pectin (polysaccharides extracted from citrus peels), which are commonly found in the UK diet (not pharmacological agents), to test their effects on systematic inflammation in the body and gut microbiome composition. Study subjects will be healthy elderly with early signs of frailty or pre-frailty from the local population and will be asked to attend the laboratory on 2 occasions; before and after 4-week' supplementing the diet daily with either 10g of pectin with 10g of whey protein and 10g of cocoa powder added as flavour (active arm) or 10g of whey protein with 10g of cocoa powder added as flavour (placebo). Participants will be given the blinded products portioned in individual sachets, with instructions to add the contents of one sachet a day to 150ml of milk and to consume immediately. At each study visit (\~90 minutes), participants will be asked to provide a stool and blood sample, will have blood pressure, heart rate, weight, height, and waist/hip ratio measured, research team will perform physical functioning test (Time up and go test, 30-second sit to stand test) as well as participants will complete the quality-of-life questionnaire (SF-36), the Depression and Anxiety (HADS) and the Gastrointestinal Symptom Rating Scale (GSRS).

Dietary Fiber Effects on the Microbiome and Satiety

Strong evidence supports the association between high fiber (HiFi) diets (e.g. legumes, nuts, vegetables) and a reduced risk for chronic conditions such as cardiovascular disease (CVD), type 2 diabetes and some forms of cancer. However, the current U.S. average consumption of dietary fiber of 17g/day is significantly below the recommendation level of 25g/d for women and 38g/d for men. Furthermore, fiber fermentation to produce short chain fatty acid (SCFA) products and alterations in microbial composition and activity may be mechanisms linking a HiFi diet to improved health. Importantly, much of the data, including findings supporting a beneficial role of SCFA have been derived from animal studies. Human studies are now needed to advance the understanding of the translational significance of rodent studies and the potential benefit of fiber on microbial metabolites and cardiometabolic health, glucose regulation, appetite and satiety. The central hypothesis is that that the mechanisms by which dietary fiber provides metabolic benefit include direct physical effects in the upper gastrointestinal tract to slow nutrient absorption, and indirect effects to reduce food intake mediated by SCFA-induced secretion of intestinal hormones resulting in increased satiety. Design: Using fiber derived from peas, Aim 1 will test the effect of a HiFi diet on appetite, satiety, and cardiometabolic health and whether elevated SCFA concentration mediates improved satiety in 44 overweight/obese subjects randomly assigned to receive either a high fiber or a low fiber dietary intervention for four weeks in a parallel arm-repeated measures design. Aim 2 will quantitate the changes in microbial composition and colonic SCFA production rate during HiFi feeding and whether any changes are potential mediators of observed benefits on satiety and cardiometabolic risk factors in 26 subjects assigned to receive a high fiber intervention for 3 weeks in a repeated measures design. Relevance: These studies will significantly expand the understanding of mechanisms by which dietary fiber improves satiety and cardiometabolic health in humans.