The Effects of Dietary Fiber on the Gut Microbiome and HDL Particles of Human Subjects

The objective of this project is to conduct a randomized-order, double-blinded cross-over trial in 20 participants to test the effects of a dietary fiber formulation on gut microbiota composition and short chain fatty acid production, lipid profiles, glucose sensitivity, intestinal permeability, overall gut health, and markers of inflammation.


Eligibility Criteria:
Inclusion Criteria:

* Healthy male and female adults 18-45 years old
* BMI: 23.0-32.0 kg/m2 ("overweight")
* Current diet includes low quantity of fiber, defined as less than approximately 15g/day, or equivalent to approximately 4 servings of fruit, vegetable, legume, or whole grain combined per day, and determined using diet recall.
* Willingness to consume prebiotic fiber drink daily for 4 weeks, and a placebo drink for 4 weeks, as well as a 4-week washout period with no intervention.
* Willingness to provide diet records, blood samples and stool samples (self-collected) biweekly for the duration of the study (7 total collections).
* Willingness to adhere to "diet control period" biweekly (eating the same, self-selected foods and abstaining from alcohol each day for 3 days prior to each stool collection/blood draw).
* General bowel movement frequency of at least once every three days and maximum of two times per day.

Exclusion Criteria:

* A plan to or desire to lose weight
* Smoker
* Anemia and difficulty with blood draws
* Currently, within previous 6 weeks of the study, or during the study taken probiotic or prebiotic formulations (food products considered to have these properties in their natural or unadulterated forms are acceptable).
* Antibiotic use during the study or within 6 months prior to study commencement.
* Medication: statins, blood pressure medications, other prescription medications
* Pregnant, planning to be pregnant or breast feeding at any point during the study or study enrollment.
* Start or change in use of hormonal birth control in the last 6 months or plans to change or start use of hormonal birth control during the study period
* Allergies to any prebiotic or placebo ingredients - Prebiotic ingredients: Resistant Tapioca Starch, Fructooligosaccharide, Sugarcane Fiber, Agave Inulin, Gum Arabic, Xanthan Gum, Apple Powder, Raspberry Powder, Blueberry Powder / Placebo Blend: Rice Flour, Xanthan Gum, Grape Powder, Plum Powder
* Illness (flu/cold in the last two weeks)
* Documented chronic diseases including diabetes, thyroid disease, metabolic syndrome, hypertension, cancer, or previous cardiovascular events
* Irritable bowel syndrome, celiac disease, or any inflammatory bowel disease (including Crohn's Disease, and/or Ulcerative colitis)
* Any immunosuppression symptoms at any point during the study or study enrollment
* Consumption of \>1 alcoholic drink/day or frequent binge drinking (\>3 alcoholic drinks in one episode) \> 1 day per month
* Plans to change or recent significant changes in lifestyle (e.g. diet or exercise routine, major travel, etc)
* Recent weight fluctuations (greater than 10% in the last six months)
* Regular use of over-the-counter pain medications (\>1/week)
* Taking prescription lipid medications (e.g. statins) or other supplements known to alter lipoprotein metabolism such as isoflavones
* Recent medical procedure such as surgery within the last 6 months
* Any changes in the above during the course of the study