The Beans to Enrich the Gut Microbiome vs. Obesity's Negative Effects (BE GONE) Trial

Study Groups:

If you are found to be eligible, you will be randomly assigned (as in the flip of a coin) to 1 of 2 study groups (intervention or control). This is done because no one knows if one study group is better, the same, or worse than the other group. Both groups will be given a diet to follow for 8 weeks.

Intervention group participants will add canned beans into their diets beginning at ½ cup per day. This will be increased to 1 cup per day during the first 2 weeks, and then will continue at 1 cup per day for the following 6 weeks of the study. You will be asked to keep a log of your bean consumption during this time.

Control group participants will be instructed to follow their normal diet (not including beans) for 8 weeks.

Length of Study:

Your active participation on the study will last a total of 20 weeks. Your participation on the study will be over after the follow-up period.

Long-Term Follow-Up:

Up to 2 times each year for up to 5 years, a member of the study staff will contact you and ask about how you are doing. You will be contacted by phone, email, or standard mail. These calls will last 15-20 minutes each.

At 6 months and 1 year after your last visit, you will complete the same questionnaires you completed at screening.

Study Visits:

At each visit, your waist measurements and weight will be collected.

Every 4 weeks (Visits 2, 3, 4, 5, and 6), blood (about 3 tablespoons) will be drawn for routine tests. You will be asked to bring a stool sample to each visit and mail a stool sample at the end of week 1 during the intervention. You will be provided with a container and instructions to collect each stool sample. You may send your stool sample back to the study staff by mail. If you choose to send it by mail, you will be given a pre-paid envelope for this.

At Visit 4, your study group assignment will be switched, and you will be assigned to the opposite group and diet from your first assignment (meaning intervention group members will be switched to the control group as well as the other way around). You will follow this new diet for the remaining 8 weeks.

Inclusion criteria

• Adult men and women 30+ years of age
• Meet criteria for overweight or obesity via BMI or waist size
• Underwent colonoscopy screening within the past 10 years
• History of pathology-confirmed precancerous polyp of the colon or rectum; OR Colorectal cancer survivor who has completed treatment with adequate maintenance of bowel length (eligible: hemicolectomy or low anterior resection; ineligible: total or near total colectomy, greater than 10 cm of small bowel resection) and normalized bowel habits
• English-speaking and reside in the greater Houston/outlying areas and/or willing to travel for study-related visits at MD Anderson
• Ability to complete web-based dietary assessments twice per week
• Willingness to provide stool samples and undergo venipuncture
• Willingness to consume/avoid beans as instructed during the 16 weeks from randomization

Exclusion criteria

• Antibiotic use in the past month and unable/unwilling to be deferred to a later recruitment date
• Current smoker
• Heavy drinker (defined as more than 14 drinks per week)
• Currently taking exclusionary prescription medications (including cytokines, immunosuppressive agents, chemopreventive drugs, bile acid sequestrants/selective cholesterol absorption inhibitors)
• Regularly taking anti flatulence medications, probiotics and/or fiber supplements and unable/unwilling to discontinue for the purpose of the study
• Major dietary restrictions relevant to the intervention
• Hereditary colorectal cancer syndromes
• Pregnant or lactating or planning to become pregnant