Effects of Distinct Nebraska-Dry Bean Market Classes on Gut Microbiota

Beans are well known for their health benefits. Many of these benefits relate to gut health, as many of the nutrients found in beans support beneficial microbes that live in the gut. However, beans have a lot of genetic diversity. This diversity has led to different bean market classes with different colors, sizes, and nutrient profiles. Differences between bean market classes may trigger different effects on gut microbes and health, but this is poorly understood. The goal of the pilot clinical trial is to make comparisons (1) between two different bean market classes (pink beans, great northern beans) and (2) between a bean mixture (pinto, kidney, black, pink, and great northern beans) and individual bean market classes. The study will assess whether bean market classes differ in their effects on gut microbes, blood pressure, metabolism, and gut symptoms in adults with and without obesity.

Bean consumption delivers diverse dietary fibers (resistant starches, non-starch polysaccharides), proteins, polyphenols, and other compounds to the colon, where they serve as substrates for the microbial community (microbiota) that colonizes the gut of humans. However, dry beans exhibit high genetic diversity, corresponding with diverse pigments and nutrients across market classes. It remains poorly understood whether targeted effects on the gut microbiota and health measures are possible with distinct dry bean market classes. The overarching study objective is to perform a randomized, crossover pilot intervention trial in adults to determine the effects of consuming distinct dry bean market classes in isolation or combination on the gut microbiota and health. The study will compare the dose-dependent effects of pink beans, great northern beans, and a five-bean mixture (pinto, kidney, black, pink, and great northern beans) on the gut microbiota, health-relevant metabolites, blood pressure, and immunometabolic markers in adults with and without extra body weight. The pilot study will employ a 3-phase, cross-over design with 2-week intervention periods separated by 2-week washout periods.

Eligibility Criteria:
Inclusion Criteria:

1. Aged 19 to 50 years.
2. Not currently pregnant or planning to become pregnant (Females Only).
3. Stable body mass index (BMI) of either 18.5-24.9 kg/m2 or 27.0-39.9 kg/m2 for the last month.
4. Has not made any major dietary changes in the last month.
5. Able to read and speak English
6. Requires no legally authorized representative (LAR).
7. Not institutionalized (e.g., prison, psychological treatment center, etc.).
8. Able to wear ambulatory blood pressure monitor and limit physical activity over a 24-hr. period.
9. Have a bowel movement at least every other day.
10. Able to collect and deliver stool samples to Innovation Campus within 4 hours of collection.
11. No known allergies or intolerance to beans.
12. Able to avoid consuming beans during the study, except for the provided beans (up to 1.5 cups/day).

Exclusion Criteria:

1. Has a cardiac device.
2. History of organ transplant
3. History of gastrointestinal surgery or disease diagnosed by a physician that involves the stomach, small, and large intestines (e.g., IBD, IBS, chronic constipation, diverticulosis, gastric bypass).
4. Recent history of cancer (excluding skin cancer) in the last year.
5. Current use of tobacco or vaping.
6. Current or recent use (last 3 weeks) of digestive enzymes, laxatives, dietary fiber, prebiotic, or probiotic supplements.
7. Medication or supplement regimen or dosage changed within the last 2 months or 3 weeks, respectively.
8. Taken antibiotics in the last 2 months.
9. Known allergies or intolerances to beans.
10. BMI 18.5-24.9 kg/m2 (normoweight): Current use of oral or injectable medications for the treatment of most chronic conditions.
11. BMI 27.0-39.9 kg/m2 (overweight): Current use of oral or injectable medications for the treatment of diabetes, hypertension, cardiovascular, liver, kidney, gastrointestinal, or autoimmune.