Fiber-rich Foods to Treat Obesity and Prevent Colon Cancer

NCT ID: NCT04780477

Last Updated: 2025-07-20

Basic Information

• Recruitment Status: ACTIVE_NOT_RECRUITING
• Clinical Phase: NA
• Total Enrollment: 60 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2021-06-29
• Study Completion Date: 2025-12-31

Brief Summary

This study tests whether a high-fiber diet based on legumes, such as dry beans, can lead to sustained reductions in obesity and colon cancer risk in persons at highest risk, namely overweight or obese, post-polypectomy patients.

Detailed Description

An important knowledge gap concerns the role of fiber in sustaining reduced energy intake to simultaneously manage weight and influence human colorectal cancer risk. Epidemiologic studies have shown an association between a high fiber diet featuring legumes (HLD) and reduced obesity and lower risk for adenoma recurrence or colorectal cancer. There are many plausible mechanisms to explain why high-fiber diets, and especially a HLD, may reduce colorectal cancer risk. First, fiber is fermented by the colonic microbiota to produce short chain fatty acids (SCFA). The SCFA, butyrate, has a remarkable array of colonic mucosal health promoting, anti-inflammatory, and anti-neoplastic properties. Secondly, microbiota break down plant cell walls releasing phytochemicals, which also have powerful anti-inflammatory and anti-carcinogenic effects. Thirdly, colonic transit is accelerated, reducing contact time with luminal carcinogens, such as heterocyclic amines formed from cooked red meat, and secondary bile acids, induced by a high fat diet and synthesized by the colonic microbiota.

Dr. Stephen O'Keefe's lab performed a human randomized controlled crossover feeding study (participants receive both diets) comparing high and low- fiber diets. The study measured mucosal biomarkers of cancer risk (proliferation - % epithelial cells staining positive for Ki67, inflammation - cluster of differentiation 3 (CD3)+ intraepithelial lymphocytes, cluster of differentiation 68 (CD68)+ lamina propria macrophages) made by fecal sampling and colonoscopy. Results suggested that within weeks these markers responded favorably to the high-fiber diet with proliferative rates and inflammatory biomarkers decreasing and microbiota composition adapting to increase butyrogenesis.

The researchers of this study have previously found that fiber may also reduce cancer risk indirectly by promoting weight loss, improving insulin sensitivity and decreasing inflammation. On average, individuals consume a similar weight of food daily; thus, replacing energy dense foods (higher kcal/g, e.g., high fat) with lower energy density foods (lower kcal/g), like legumes, should potentiate weight control. Viscous fiber intake is associated with longer gastric emptying times which over time might contribute to postponing the next eating occasion. Diet may also induce changes in gut microbiome composition leading to negative energy balance. Emerging human evidence links the gut microbiome with insulin resistance, inflammation, and obesity and with adenomatous polyps and colon cancer. In this current study, characterizing gut motility, microbiome, and metabolome composition profiles that may influence weight loss and have a role in the prevention or recurrence of adenomas and colorectal cancer, will provide novel and potentially therapeutic information.

The goal of the research is to conduct a clinical trial featuring study-provided pre-portioned entrées and strategic nutritional instruction to guide participants to integrate legumes into a healthy high-fiber diet pattern. Participants will be provided two entrées per day during months 1 through 3, and one entrée per day during months 4 through 6. Participants will continue their diets during months 7 through 12 but will be responsible for food preparation. The research will target a population at high risk for colorectal cancer, overweight and obese participants with a history of a colon polyp in the past 3 years, to test whether a high-legume, high-fiber diet will simultaneously increase weight loss and suppress intestinal biomarkers of cancer risk compared to a control diet (healthy American). In addition, it will explore potential mechanisms through which the high-legume intervention diet facilitates weight loss and intestinal health.

Conditions

Colon Cancer; Obesity

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: PREVENTION
• Blinding Strategy: DOUBLE

Study Groups

High Fiber Diet Featuring Legumes (HLD)

Participants randomized to the high fiber diet featuring legumes (HLD) will add approximately 30 grams of dietary fiber per day from legume dishes, ensuring a total intake of approximately 50 grams of dietary fiber per day.

Group Type: EXPERIMENTAL

High Fiber Diet Featuring Legumes (HLD)

Intervention Type: DIETARY_SUPPLEMENT

The high fiber diet featuring legumes (HLD) provides pre-portioned entrées for two meals per day in months 1-3, and one meal per day in months 4-6. Participants continue on the diet in months 7-12 but assume responsibility for food preparation. The HLD will contain approximately 250 grams (g) of legumes per day (\~1 ½ cups cooked legumes) in months 1-3 provided in two pre-portioned single serving entrées (i.e. \~125g in each serving). A study nutritionist provides in-person and written guidance for including side dishes that are nutritionally balanced with energy intake to lose 1-2 pounds of weight per week.

Healthy American Diet Control Arm

Participants randomized to the healthy American diet control arm will receive pre-portioned meal replacement entrées with legumes replaced by lean chicken or meat.

Group Type: ACTIVE_COMPARATOR

Healthy American Diet

Intervention Type: DIETARY_SUPPLEMENT

The healthy American diet provides pre-portioned meal replacement entrées with legumes replaced by lean chicken or meat. Participants continue on the diet in months 7-12 but assume responsibility for food preparation. A study nutritionist provides in-person and written guidance for including side dishes that are nutritionally balanced with energy intake to lose 1-2 pounds of weight per week.

Interventions

High Fiber Diet Featuring Legumes (HLD)

The high fiber diet featuring legumes (HLD) provides pre-portioned entrées for two meals per day in months 1-3, and one meal per day in months 4-6. Participants continue on the diet in months 7-12 but assume responsibility for food preparation. The HLD will contain approximately 250 grams (g) of legumes per day (\~1 ½ cups cooked legumes) in months 1-3 provided in two pre-portioned single serving entrées (i.e. \~125g in each serving). A study nutritionist provides in-person and written guidance for including side dishes that are nutritionally balanced with energy intake to lose 1-2 pounds of weight per week.

Intervention Type: DIETARY_SUPPLEMENT

Healthy American Diet

The healthy American diet provides pre-portioned meal replacement entrées with legumes replaced by lean chicken or meat. Participants continue on the diet in months 7-12 but assume responsibility for food preparation. A study nutritionist provides in-person and written guidance for including side dishes that are nutritionally balanced with energy intake to lose 1-2 pounds of weight per week.

Intervention Type: DIETARY_SUPPLEMENT

Eligibility Criteria

Inclusion Criteria

• free-living adults 40 to 75 years old
• BMI 25-40 kg/m^2
• able to provide documentation confirming a colonoscopy within 3 years that found ≥1 adenoma >0.5 cm or a sessile serrated polyp (any)
• English speaking
• ambulatory, able to pick up food, participate in clinical exams and laboratory tests
• able to provide informed consent

Exclusion Criteria

• serious and/or unstable medical condition as deemed by study physician
• history of colorectal cancer, bowel resection, polyposis syndrome, or inflammatory bowel disease
• smoked regularly in the past year
• dietary restrictions substantially limiting compliance (e.g., must be willing to be randomized to either diet)
• planning on substantially changing usual exercise behavior in the next 6 months
• regular or recent use of prescription medication that may alter inflammation markers or gut function as deemed by study physician
• pregnant women, breast feeding women, or women planning pregnancy within the year of active study participation

• Minimum Eligible Age: 40 Years
• Maximum Eligible Age: 75 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

National Cancer Institute (NCI)

NIH

Sponsor Role: collaborator

Emory University

OTHER

Sponsor Role: lead

Responsible Party

Terry Hartman

Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Terry Hartman, PhD, MPH, RD

Role: PRINCIPAL_INVESTIGATOR

Emory University

Locations

Rollins School of Public Health, Emory University

Atlanta, Georgia, United States

Countries

United States

References

Hartman TJ, Christie J, Wilson A, Ziegler TR, Methe B, Flanders WD, Rolls BJ, Loye Eberhart B, Li JV, Huneault H, Cousineau B, Perez MR, O'Keefe SJD. Fibre-rich Foods to Treat Obesity and Prevent Colon Cancer trial study protocol: a randomised clinical trial of fibre-rich legumes targeting the gut microbiome, metabolome and gut transit time of overweight and obese patients with a history of noncancerous adenomatous polyps. BMJ Open. 2024 Feb 5;14(2):e081379. doi: 10.1136/bmjopen-2023-081379.

Reference Type: DERIVED

PMID: 38316601 (View on PubMed)

Provided Documents

Document Type: Informed Consent Form

View Document

Other Identifiers

R01CA245063

Identifier Type: NIH

Identifier Source: secondary_id

View Link

STUDY00000563

Identifier Type: -

Identifier Source: org_study_id