Effects of High-Fiber Diet on Gut Microbiota, Metabolism, and Immune Microenvironment in Solid Tumor Patients: A Clinical Study

August 29, 2026 updated by: Xuelei Ma MD, West China Hospital
Cancer remains a major global public-health challenge and a central focus of medical research. According to the International Agency for Research on Cancer (IARC, 2020), 19.29 million new malignant tumors and 9.96 million cancer deaths occurred worldwide, >90% being solid cancers. Lung cancer alone accounted for 2.2 million new cases and 1.8 million deaths; >75% of patients were already at an advanced stage at diagnosis. Current options for late-stage solid tumors are limited: surgery is often impossible because of metastasis; cytotoxic chemotherapy produces dose-limiting toxicities (grade III-IV myelosuppression 15-40%, mucositis 50-80%); radiotherapy risks pneumonitis (5-15%) or enteritis (5-20%) when tumors abut vital organs; targeted agents succumb to acquired resistance after a median 9-13 months; and immune-checkpoint inhibitors achieve <40% objective response with 7-15% grade 3-4 immune-related adverse events. Dietary intervention is therefore emerging as a promising adjunct. Dietary fibre protects against cardiovascular and metabolic diseases, yet intake is universally low. WHO and the Chinese Nutrition Society recommend 25-30 g total fibre per day (approximately 15-21 g insoluble), whereas Chinese adults consume only approximately 11 g insoluble fibre. High-fibre diets reshape gut microbiota, augment short-chain fatty acid (SCFA) production, strengthen intestinal barrier function, activate CD8⁺ T cells and dampen regulatory T cells, thereby enhancing anti-tumour immunity. A melanoma cohort showed improved progression-free survival under immunotherapy when fibre intake was high. Similar microbiota-immune axes may operate in colorectal and other solid cancers, but clinical data are scarce. This study examines whether supplementation with 16-20 g/day of dietary fibre for 6 weeks modulates gut-microbiota composition, faecal short-chain fatty acid profiles, and peripheral-blood immune-cell subsets in patients with solid tumours. The findings may clarify whether fibre-driven microbiota-immune crosstalk can be harnessed as a personalised nutritional strategy in patients with cancer.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
17

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • China
    • Sichuan
      • Chengdu, Sichuan, China
        • West China Hospital
      • Chengdu, Sichuan, China, 611430
        • Xinjin District Hospital of Traditional Chinese Medicine

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • (1) Sign a written informed consent form before any study-related procedures are carried out.
  • (2) Males or females, aged 18-75 years old.
  • (3) Diagnosed with solid tumors by pathological tissue biopsy.
  • (4) According to the RECIST v1.1 (Response Evaluation Criteria in Solid Tumors Version 1.1) criteria, there is at least 1 measurable lesion (lesions previously treated with local therapies such as radiotherapy cannot be regarded as measurable lesions).
  • (5) ECOG (Eastern Cooperative Oncology Group Performance Status) score of 0-1.
  • (6) NRS-2002 (Nutritional Risk Screening 2002) score < 3.
  • (7) BMI (Body Mass Index) ≥ 18.5 (can be adjusted appropriately according to the actual situation).
  • (8) Patients who can eat orally or through a feeding tube and can tolerate enteral nutrition.
  • (9) Sufficient organ function, and the subjects need to meet the following laboratory indicators: In the absence of granulocyte-colony-stimulating factor use in the past 14 days, the absolute neutrophil count ≥ 1.5×10⁹/L.

Platelets ≥ 75×10⁹/L. In the absence of blood transfusion or erythropoietin use in the past 7 days, hemoglobin ≥ 8 g/dL.

Serum albumin ≥ 3.0 g/dL. Total bilirubin ≤ 1.5× the upper limit of normal (ULN). Aspartate Aminotransferase (AST) and Alanine Aminotransferase (ALT) ≤ 2.5×ULN. In case of liver metastasis, ALT and/or AST ≤ 5×ULN, and total bilirubin ≤ 3×ULN. In case of liver or bone metastasis, Alkaline Phosphatase (AKP) ≤ 5×ULN.

Creatinine clearance rate ≥ 50 mL/min (calculated according to the Cockcroft - Gault formula) or serum creatinine ≤ 1.5×ULN.

International Normalized Ratio (INR) ≤ 1.5×ULN, Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT) ≤ 1.5×ULN.

Urine protein < 2+ (if urine protein ≥ 2+, a 24-hour urine protein quantification can be performed, and subjects with a 24-hour urine protein quantification < 2.0 g can be enrolled).

  • (10) Women of childbearing potential must agree to abstain from heterosexual intercourse or use a reliable and effective contraceptive method from the time of signing the informed consent form until at least 6 months after the last administration of concomitant anticancer treatment. A serum human chorionic gonadotropin (HCG) test must be negative within 3 days before initiation of the study intervention, and the participant must not be breastfeeding. Women are considered to be of childbearing potential unless they are postmenopausal, defined as amenorrhea for at least 12 consecutive months without an alternative medical cause, or have undergone surgical sterilization, such as hysterectomy, bilateral tubal ligation, or bilateral oophorectomy.
  • (11) If there is a risk of pregnancy, all subjects (regardless of sex) must use a contraceptive method with an annual failure rate of less than 1% throughout the treatment period and until 120 days after the last administration of concomitant anticancer treatment, or 180 days after the last administration of chemotherapy.

Exclusion Criteria:

  • (1) Patients with cognitive impairment or mental illness who are unable to understand the study content.
  • (2) Patients with central nervous system or meningeal metastases.
  • (3) Patients with clinically symptomatic moderate or severe ascites (that is, those who require therapeutic paracentesis within 2 weeks before the start of study treatment; patients with only a small amount of ascites shown on imaging and no clinical symptoms can be enrolled).
  • (4) Patients with uncontrolled or moderate to severe pleural effusion and pericardial effusion.
  • (5) Patients with severe diarrhea, intractable vomiting, severe malabsorption syndrome, paralytic and mechanical intestinal obstruction; tracheoesophageal fistula, gastrointestinal perforation or gastrointestinal fistula, or abdominal abscess; patients with extra - gastrointestinal bleeding with a CTCAE (Common Terminology Criteria for Adverse Events) grade 3 or above within 6 months before the start of study treatment or grade 2 or above within 3 months (such as abnormal vaginal bleeding, hematemesis).
  • (6) Patients known to be allergic to any component of the dietary fiber supplement.
  • (7) Patients with poorly controlled diabetes.
  • (8) Patients with poorly controlled hypertension (systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg under routine antihypertensive treatment), with a history of hypertensive crisis or hypertensive encephalopathy.
  • (9) Patients with severe cardiovascular and cerebrovascular diseases, including cerebrovascular accident (CVA), transient ischemic attack (TIA), myocardial infarction, and major vascular diseases within 6 months before enrollment (including but not limited to aortic aneurysms requiring surgical repair or recent arterial thrombosis); patients with poorly controlled clinical symptoms or heart diseases, such as unstable angina pectoris, NYHA (New York Heart Association) heart failure grade II or above, left ventricular ejection fraction < 50% on color Doppler echocardiography, or severe arrhythmias that cannot be controlled by drug treatment.
  • (10) Pregnant or lactating women.
  • (11) Other situations considered by the investigator as inappropriate for enrollment.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: high-insoluble-fibre diet
Dietary supplement: High-fibre diet
Dietary fibre, recommended at 25-30 g/day (15-21 g/day insoluble fibre), is chronically under-consumed (approximately 11 g/day in China). High-fibre diets increase short-chain fatty acid (SCFA) production, enhance gut-barrier integrity, and boost antitumour immunity, and higher dietary fibre intake has been associated with better immunotherapy outcomes in patients with melanoma. Clinical evidence in patients with solid tumours remains limited. Participants received 16-20 g/day of supplemental dietary fibre for 6 weeks in addition to their usual diet while continuing their prescribed anticancer treatment. The study evaluates whether this dietary intervention is associated with changes in gut microbiota composition, faecal short-chain fatty acid concentrations, and peripheral blood immune-cell subsets.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Incidence, Type, Frequency, and Severity of Intervention-Emergent Adverse Events
Time Frame: From the first intake of the dietary fiber supplement through the end of the 6-week intervention period
The incidence, type, frequency, and severity of intervention-emergent adverse events, with particular attention to gastrointestinal adverse events, including constipation, abdominal distension, abdominal pain, nausea, vomiting, and diarrhea.
From the first intake of the dietary fiber supplement through the end of the 6-week intervention period

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change in fecal gut microbiota composition
Time Frame: Baseline and week 6 after initiation of the dietary intervention.
Changes from baseline in fecal gut microbiota composition, including microbial diversity and the relative abundance of bacterial taxa, following the high-fiber dietary intervention.
Baseline and week 6 after initiation of the dietary intervention.
Change in fecal short-chain fatty acid concentrations
Time Frame: Baseline and week 6 after initiation of the dietary intervention.
Changes from baseline in fecal short-chain fatty acid concentrations, including acetate and butyrate, following the high-fiber dietary intervention.
Baseline and week 6 after initiation of the dietary intervention.
Change in peripheral blood immune-cell subsets
Time Frame: Baseline and week 6 after initiation of the dietary intervention.
Changes from baseline in the proportions and phenotypic characteristics of peripheral blood immune-cell subsets following the high-fiber dietary intervention, as assessed by flow cytometry.
Baseline and week 6 after initiation of the dietary intervention.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
West China Hospital

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Xinjin District Hospital of Traditional Chinese Medicine

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
December 1, 2025

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
June 25, 2026

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
June 30, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
March 12, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 12, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 17, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
September 3, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 29, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
August 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • Approval No. 1038 (2025)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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