High Fiber Diet for Obesity and Colon Cancer

Overseen By Terry Hartman, PhD, MPH, RD

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: Emory University

Must not be taking: Anti-inflammatories, Gut-altering drugs

Disqualifiers: Colorectal cancer, Bowel resection, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 6

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to determine if a high-fiber diet, particularly one rich in legumes like beans, can reduce obesity and the risk of colon cancer in individuals who are overweight and have had certain types of colon polyps removed. Participants will follow either this high-fiber diet or a healthy American diet for comparison. Individuals who have been overweight, have had a colon polyp removed within the last three years, and can manage dietary changes might be suitable for this trial. As an unphased trial, this study provides a unique opportunity to contribute to significant dietary research that could benefit many people.

Do I have to stop taking my current medications for the trial?

The trial does not specify if you must stop taking your current medications, but you cannot participate if you regularly use prescription medication that may alter inflammation markers or gut function.

Will I have to stop taking my current medications?

The trial excludes people who regularly or recently use prescription medication that may affect inflammation markers or gut function, so you might need to stop taking such medications. It's best to discuss your specific medications with the study team.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Research has shown that a high-fiber diet, particularly one rich in beans and lentils, can help reduce obesity and the risk of colon cancer. Studies have found that both soluble and insoluble fibers improve gut health and lower cancer risk. Thus, increasing fiber intake can decrease the likelihood of developing colorectal cancer.

Regarding safety, most people tolerate high-fiber diets well. Some may experience mild digestive changes, such as bloating or gas, as their bodies adjust to increased fiber. These effects are usually temporary. Overall, a high-fiber diet is considered safe and can greatly benefit health. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about the High Fiber Diet (HFD) for obesity and colon cancer because it emphasizes a natural approach using legumes to significantly boost dietary fiber intake. Unlike standard treatments, such as medication or surgery, this diet aims to harness the power of approximately 50 grams of dietary fiber per day to potentially reduce cancer risk and support weight management. The unique feature of focusing on legumes offers both a high fiber content and other beneficial nutrients, setting it apart from typical dietary interventions that might not prioritize fiber as heavily.

What evidence suggests that this trial's treatments could be effective for obesity and colon cancer?

Research has shown that a high-fiber diet, particularly one rich in beans, can lower the risk of colon cancer and aid in weight loss. Studies have found that consuming an additional 10 grams of fiber daily can reduce the risk of colorectal cancer by 10–17%. Fiber speeds up the movement of food through the colon, reducing the time harmful substances contact the colon. Additionally, a high-fiber diet is linked to improved health markers associated with a lower risk of colon cancer. In this trial, participants in the High Fiber Diet Featuring Legumes (HLD) arm will follow a fiber-rich diet, which has demonstrated potential for weight loss and effectiveness in managing obesity. Meanwhile, participants in the Healthy American Diet Control Arm will follow a different dietary plan. ^{2 3 6 7 8}

Who Is on the Research Team?

Terry Hartman, PhD, MPH, RD

Principal Investigator

Emory University

Are You a Good Fit for This Trial?

This trial is for English-speaking adults aged 40-75 who are overweight or obese (BMI 25-40), can move around on their own, and have had a colonoscopy that found polyps in the last 3 years. It's not for those with serious health issues like cancer or heart disease, recent smokers, people with dietary restrictions, those changing exercise habits significantly soon, regular users of certain medications affecting gut function or inflammation markers, or women who are pregnant.

Inclusion Criteria

Colonoscopy within 3 years that found ≥1 adenoma >0.5 cm

I can walk, eat by myself, undergo tests, and understand consent forms.

BMI 25-40 kg/m2

Exclusion Criteria

Planning on substantially changing usual exercise behavior in the next 6 mos

Pregnant women, breast feeding women, or women planning pregnancy within the year of active study participation

I have a history of colorectal cancer, bowel surgery, multiple polyps, or chronic bowel inflammation.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Intensive Treatment

Participants receive two pre-portioned entrées per day featuring legumes during months 1 through 3

3 months

Monthly visits for monitoring and dietary guidance

Maintenance Treatment

Participants receive one pre-portioned entrée per day during months 4 through 6

3 months

Monthly visits for monitoring and dietary guidance

Self-directed Diet

Participants continue the high-fiber diet on their own during months 7 through 12

6 months

Visits at month 6 and month 12 for outcome measurements

Follow-up

Participants are monitored for safety and effectiveness after treatment

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Healthy American Diet
• High Fiber Diet (HFD)

Trial Overview The study tests if a high-legume, high-fiber diet leads to more weight loss and lower intestinal cancer risk markers compared to a standard healthy American diet among individuals at risk for colorectal cancer due to obesity and previous polyps.

How Is the Trial Designed?

Group I: High Fiber Diet Featuring Legumes (HLD) Experimental Treatment 1 Intervention

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 II: Healthy American Diet Control Arm Active Control 1 Intervention

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

Who Is Running the Clinical Trial?

Emory University

Lead Sponsor

Trials

1,735

Recruited

2,605,000+

National Cancer Institute (NCI)

Collaborator

Trials

14,080

Recruited

41,180,000+

Published Research Related to This Trial

In a study using a dimethylhydrazine model for colon cancer, rats fed diets high in fat showed an increased incidence and number of tumors, highlighting the role of dietary fat in colon carcinogenesis.

Adding dietary fiber to high-fat diets provided significant protection against tumor development, with complete protection observed when saturated fat was combined with fiber, suggesting that fiber can counteract the harmful effects of fat on colon health.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The fat/fiber antagonism in experimental colon carcinogenesis. Trudel, JL., Senterman, MK., Brown, RA.[2017]

Higher fiber intake is associated with a reduced risk of colorectal cancer (CRC), as it promotes the production of butyrate, a compound with anti-cancer properties.

Conversely, a high-fat diet increases CRC risk by enhancing the conversion of bile acids into harmful compounds like deoxycholic acid, suggesting that managing fiber and fat intake could be effective strategies for CRC prevention.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Fiber, Fat, and Colorectal Cancer: New Insight into Modifiable Dietary Risk Factors. Ocvirk, S., Wilson, AS., Appolonia, CN., et al.[2023]

While some studies suggest a negative association between dietary fiber intake and colon cancer rates, the evidence remains inconsistent and inconclusive, with some studies even indicating a potential positive association in certain populations.

Despite the lack of definitive proof that fiber protects against colorectal cancer, dietary guidelines promoting increased consumption of fiber-rich foods like cereals, fruits, and vegetables are still recommended as they are unlikely to cause harm and may contribute to overall health.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Fiber intake in different populations and colon cancer risk. McKeown-Eyssen, GE.[2019]

In a study of 88,757 women over 16 years, no significant link was found between dietary fiber intake and the risk of developing colorectal cancer, with a relative risk of 0.95 for the highest fiber intake compared to the lowest.

The research also showed no protective effect of dietary fiber against colorectal adenomas, suggesting that increasing fiber consumption may not reduce the risk of these conditions.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Dietary fiber and the risk of colorectal cancer and adenoma in women. Fuchs, CS., Giovannucci, EL., Colditz, GA., et al.[2022]

Epidemiological studies suggest that increasing dietary fiber intake and reducing dietary fat may help lower the risk of developing colon cancer in humans.

Among various dietary fibers, wheat bran has shown the most promise in inhibiting colon tumor development, although animal studies have produced mixed results due to methodological differences.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Dietary fiber and colon cancer: animal model studies. Reddy, BS.[2019]

A review of 37 observational studies and meta-analyses of 16 case-control studies suggests that a high-fiber diet is associated with a reduced risk of colon cancer, with an estimated odds ratio of 0.57, indicating a significant protective effect.

While both fiber intake and vegetable consumption appear to lower colon cancer risk, the specific contributions of dietary fiber versus other beneficial components in vegetables remain unclear, as both factors are correlated.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Dietary fiber, vegetables, and colon cancer: critical review and meta-analyses of the epidemiologic evidence. Trock, B., Lanza, E., Greenwald, P.[2022]

A diet high in dietary fiber, particularly from wheat bran, is associated with a reduced risk of colon cancer, as shown in various studies including case-control and animal models.

Wheat bran specifically inhibits colon tumor development more effectively than other fiber sources like oat and corn bran, and it reduces levels of tumor promoters in the colon, highlighting its potential as a protective dietary component.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Role of dietary fiber in colon cancer: an overview. Reddy, BS.[2019]

In a study of 47,949 U.S. male health professionals, high intake of red meat was associated with a significantly increased risk of colon cancer, with a relative risk of 1.71 for those consuming the most compared to the least red meat.

Men who consumed beef, pork, or lamb five or more times a week had an even higher relative risk of 3.57 for developing colon cancer, indicating a strong link between red meat consumption and cancer risk.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Intake of fat, meat, and fiber in relation to risk of colon cancer in men. Giovannucci, E., Rimm, EB., Stampfer, MJ., et al.[2019]

Higher intake of dietary fibers, found in fruits and vegetables, is associated with a decreased risk of developing colorectal cancer, especially in populations that switch from a high red meat and fat diet to a fiber-rich diet.

Increased fiber consumption is also linked to lower mortality rates from colorectal cancer, highlighting the protective benefits of dietary fibers against this disease.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Protective effect of dietary fibers against colorectal carcinoma. Mia, MA., Siddiqui, MN., Rukunuzzaman, M., et al.[2017]

In a study involving 20 C57BL/6J Apc Min/+ mice over 60 days, high-fat diets without fiber were linked to a significantly higher incidence of small bowel tumors compared to diets with fiber, suggesting that fiber may offer protective effects against these tumors.

Despite variations in fiber content, the study found that high-fat diets increased tumor burden and colonic atypical hyperplasia, indicating that dietary fat may have a more pronounced effect on tumor development than fiber in this model, particularly for colon cancer.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Differential dietary effects on colonic and small bowel neoplasia in C57BL/6J Apc Min/+ mice. Yu, CF., Whiteley, L., Carryl, O., et al.[2019]

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC11671356/

Dietary fiber influence on overall health, with an emphasis on ... Dietary fiber can lower the risk of CVD, colon cancer and also, type II diabetes mellitus (27).

2. cancer.gov cancer.gov/clinicaltrials/NCI-2020-04372

Fiber-Rich Foods for the Treatment of Obesity and ... A natural high-fiber diet based on legumes may lead to greater weight loss and improvements in biomarkers associated with colon cancer risk compared to a ...

3. ncbi.nlm.nih.gov ncbi.nlm.nih.gov/books/NBK585999/

The Role of Diet and Lifestyle in Colorectal Cancer Incidence ... With each 10g/day of total dietary fiber, a 10–17% CRC risk reduction is observed. This relationship is likely due to dietary fiber decreasing colonic transit ...

4. sciencedirect.com sciencedirect.com/science/article/pii/S0016508523051399

High Soluble Fiber Promotes Colorectal Tumorigenesis ... Our research raises the hypothesis that very high dietary intake of soluble fiber could be deleterious for individuals at higher risk of colorectal cancer.

5. foodandnutritionresearch.net foodandnutritionresearch.net/index.php/fnr/article/view/11034/18662

Dietary fiber consumption and outcomes of different cancers Research indicates that higher dietary fiber intake may reduce the risk of cancers such as colorectal, breast, and endometrial cancer.

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC10860035/

Fibre-rich Foods to Treat Obesity and Prevent Colon Cancer ... A high-fibre diet featuring legumes will simultaneously facilitate weight reduction and suppress colonic mucosal biomarkers of colorectal cancer (CRC).

7. nature.com nature.com/articles/s41467-024-55219-5

Diet-wide analyses for risk of colorectal cancer We report here on a systematic analysis of 97 dietary factors and subsequent colorectal cancer risk using a diet-wide association study

8. sciencedirect.com sciencedirect.com/science/article/pii/S2666154325003709

The association of dietary fiber intake with colorectal ... This study suggested that increased dietary fiber intake may be protective against CRC, particularly in males. Vulcan et al. [19] analyzed data from the Malmö ...