Mechanisms Linking Dietary Fiber, the Microbiome and Satiety
University of Missouri-Columbia
Summary
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.
Description
Dietary patterns with high fiber content are linked to a lower risk for the development of cardiovascular disease \[1-3\], hypertension \[4\], type 2 diabetes \[5\] and increased body weight \[4\]. Potential biological mechanisms that may mediate these beneficial health effects include a slowing of the absorption of meal carbohydrate (CHO) \[6-11\], reduction in blood lipids \[8,12\] and an increase in the release of satiety hormones \[10,13\]. The PI has previously shown that compared to low-fiber (LowFi) meals, high-fiber (HiFi) meals reduced blood glucose concentrations postprandially by 11…
Eligibility
- Age range
- 20–55 years
- Sex
- All
- Healthy volunteers
- Yes
Inclusion 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 ≥…
Interventions
- OtherDietary fiber: 10-25g
10-25 g/day of fiber
- OtherDietary fiber: 5g
5 g/day of fiber
Location
- University of Missouri-ColumbiaColumbia, Missouri