Performing Department
(N/A)
Non Technical Summary
Our long-term goal is to mechanistically understand how dietary fibers promote gut bacterial shifts that effectively translate into health benefits to humans. In this sense, we have shown that key bacteria associated with reduced inflammation and enhanced gut barrier function, theClostridiumclusters IVandXIVa, are better supported withfermentable insoluble fibers and matrix-entrapped soluble fibers than soluble fibers alone. The former cell wall-type fibers are abundant in whole food sources, which are reduced in modern Western diets and are often replaced with isolated soluble fibers, like inulin, in processed foods.Our aim is to compare whole food fibersversusinulin for support of butyrogenicClostridiumclusters IV and XIVagrowth, and to evaluate associated health biomarkers. Whole food fibers and whole food fiber mixtures will be fermentedin vitroand analyzed for increase inClostridiumclusters IVandXIVaandbutyrate production. Based onin vitrofecal fermentation results, a whole food dietary fiber mixture will be selected for a crossover human trial to compare whole food dietary fibersversusinulin and monitored forimproved gut and systemic health biomarkers.These studies combine expertise between Purdue University and Rush Medical Center to bring an understanding of health outcomes from fiber use. They are innovative since most of fibers currently added to processed foods are soluble, and, if proved right, will show that whole food dietary fibers constitute a better dietary approach for good gut and whole-body health.
Animal Health Component
0%
Research Effort Categories
Basic
30%
Applied
50%
Developmental
20%
Goals / Objectives
Our long-term goal is to mechanistically understand how dietary fibers promote gut bacterial shifts that effectively translate into health benefits to humans. In this sense, we have shown that key bacteria associated with reduced inflammation and enhanced gut barrier function, theClostridiumclusters IVandXIVa, are better supported withfermentable insoluble fibers and matrix-entrapped soluble fibers than soluble fibers alone. The former cell wall-type fibers are abundant in whole food sources, which are reduced in modern Western diets and are often replaced with isolated soluble fibers, like inulin, in processed foods.Our aim is to compare whole food fibersversusinulin for support of butyrogenicClostridiumclusters IV and XIVagrowth, and to evaluate associated health biomarkers. Whole food fibers and whole food fiber mixtures will be fermentedin vitroand analyzed for increase inClostridiumclusters IVandXIVaandbutyrate production. Based onin vitrofecal fermentation results, a whole food dietary fiber mixture will be selected for a crossover human trial to compare whole food dietary fibersversusinulin and monitored forimproved gut and systemic health biomarkers.
Project Methods
In vitrofecal fermentations of 20 individual whole food fibers (4 from each of the following groups: fruits, vegetables/fungi, cereals and grains, pulses, roots and tubers) will be used to select one from each whole food group that has highest butyrate andClostridiumcluster XIVa and IV levels. The selected 5 whole foods will used to make 10 different 3-component fiber mixtures (i.e., to account for all possible 3-component mixture combinations). These mixtures will be subjected to a newin vitrofecal fermentation for the selection of the whole food fiber mixture that has the highest butyrate andClostridiumcluster XIVa and IV levels to be used in the clinical trial. The approach of mixing the different fibers will be used to reflect the different whole food sources that can promote butyrogenicClostridiumclusters XIVa and IV in dietary patterns.In vitrofecal fermentations (Objective 1) and the human supplementation study (Objective 2) will be done at Purdue University under Institutional Review Board approval. Blood marker analyses for the human study will be done at Rush Medical School.A two-stage selection process will be used based onin vitrofecal fermentation outcomes ofhighest butyrate andClostridiumcluster XIVa and IV levels of1) 20 whole food fibers prepared as if consumed whole, and 2) 10 fiber mixtures using the best candidates from each whole food group tested (fruits, vegetables/fungi, cereals and grains, pulses, roots and tubers). One whole food fiber mixture will be selected and tested compared to inulin in a crossover design human supplementation trial.A crossover, randomized (concealed, block randomization for the order of treatment given), double-blind trial will be performed with overweight, prediabetic subjects.To assure that microbiota and metabolic outcomes will be observed, recruited subjects will receive two treatments (whole food mixture treatment and inulin treatment) for a duration of 4 weeks each, with a 4-week wash-out period in-between treatments.Primary outcomes will be changes in stool Clostridia butyrate-producing bacteria and butyrate levels. Secondary outcomes will include changes in stool microbiota community, serum SCFA, serum markers of intestinal barrier integrity (serum zonulin, ZO-1 and intestinal fatty acid binding protein) and intestinal leakiness (lipopolysaccharides-LPS and lipopolysaccharides binding protein - LBP), markers of systemic inflammation (IL-6, hsCRP), and metabolic function (HOMA-IR Score).Fecal collections will occur just before each of the supplementation periods and every week during supplementation and blood draws will occur at the beginning and end of each supplementation period. Shifts in bacterial groups will be assessed through 16S rRNA gene sequencing and SCFA analysis will be performed on all fecal samples collected to compare bacterial composition and metabolism shifts promoted by the whole food fiber mixtureversusinulin.Potential changes in dietary fiber intake and overall diet during the course of the study will be evaluated from a three-day food recall collected using the Automated Self-Administered 24-hour Dietary Assessment Tool (ASA24, 2020 - National Cancer Institute, Bethesda, MD)at the end of each supplementation cycle, and the obtained dietary information will be added as random effect to our model. Blood markers of gut metabolites (SCFAs), intestinal barrier integrity, bacterial translocation, systemic inflammation, and metabolic health will be analyzed at the beginning and end of each supplementation period to evaluate if the shifts promoted by whole foodversusinulin reflect in gut and systemic health benefits.Compliance will be measured through the return of unopened sachets twice over each of the treatment periods, at the end of each treatment period. Researchers will call every week during the treatment period to remind subjects to take the treatments and ask if they have missed taking any of the treatments during that week. Tolerability will be determined through completion of the PROMIS(Spiegelet al., 2014)gastrointestinal symptom scales at baseline and every week during each treatment end to assess change in GI symptoms with fiber supplementation. When researchers call subjects to assess compliance, open-ended questions will be also asked about the tolerability of the supplements and if subjects have experienced any side effects. Side effects will be documented as adverse events as appropriate. Safety will further be assessed by CMP and CBC at both baseline and treatment end.