Dietary Fiber Effects on the Microbiome and Satiety

Description

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.

Conditions

Dietary Fiber

Study Overview

Study Details

Study overview

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.

Mechanisms Linking Dietary Fiber, the Microbiome and Satiety

Dietary Fiber Effects on the Microbiome and Satiety

Condition
Dietary Fiber
Intervention / Treatment

-

Contacts and Locations

Columbia

University of Missouri-Columbia, Columbia, Missouri, United States, 65212

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

For general information about clinical research, read Learn About Studies.

Eligibility Criteria

  • * Men and women (premenopausal only)
  • * Age 20-55y (Aim 1); 45-55y (Aim 2)
  • * BMI ≥25 or ≤35 kg/m2 (Aim 1); ≥25 or ≤40 (Aim 2)
  • * Weight stable (no fluctuations in body weight of greater than 4 kg in the last 3 months)
  • * Willing to consume a research diet
  • * Willing to provide blood and fecal samples
  • * At least one characteristic of the metabolic syndrome (but not diabetic)
  • 1. A large waistline: 35 inches or more for women 40 inches or more for men 2. High triglycerides: 150 mg/dL or higher 3. Low HDLc level: \<50 mg/dL for women \<40 mg/dL for men 4. High blood pressure ≥130/85 mmHg 5. Fasting blood sugar ≥100 mg/dL
  • * Pre-diabetes acceptable (glucose \<125 mg/dL or HbA1c \<6.5%)
  • * Stably treated with statin drugs, anti-hypertensives, and anti-depressants. These are acceptable as long as the drug category does not alter appetite, body weight, or the microbiome (if known)
  • * Pregnant or lactating
  • * Postmenopausal (evidence suggests an interplay between the gut microbiome)
  • * BMI of \<25 or \>35 kg/m2 (Aim 1); \<25 or \>40 kg/m2 (Aim 2)
  • * Use of medications that affect the gut microbiome (e.g. antibiotics)
  • * Taking medications known to affect appetite (e.g., phentermine) or gastrointestinal function (e.g., metformin)
  • * On a special diet or undergoing weight loss, vegetarian, or other restricted dietary patterns
  • * Ad libitum intake of fiber above 25g/day (mean intake in the US population is 17g/day) and \< 10g/d
  • * Ad libitum alcohol intake of greater than 1 drink/d for women and 2 drinks/d for men
  • * History of disease (example colon cancer, HIV, cardiovascular disease, psychiatric disorders, etc.)
  • * Use of tobacco products
  • * Having metal or implants in the body that are not MRI compatible (Aim 1 only)

Ages Eligible for Study

20 Years to 55 Years

Sexes Eligible for Study

ALL

Accepts Healthy Volunteers

Yes

Collaborators and Investigators

University of Missouri-Columbia,

Study Record Dates

2025-08-01