Fecal Microbiota Transplantation in Children With Autism Spectrum Disorder and Gastrointestinal Symptoms (FMT-ASD-GI)

January 22, 2026 updated by: dr n.med. Anna Liber, Institute of Mother and Child, Warsaw, Poland

Fecal Microbiota Transplantation in Children With Autism Spectrum Disorder and Gastrointestinal Symptoms: A Pilot Study

The aim of the study is to evaluate the effectiveness and safety of fecal microbiota transplantation (FMT) in reducing gastrointestinal (GI) and behavioral symptoms in children with autism spectrum disorder (ASD).

Children with ASD often experience GI problems such as constipation, diarrhea, and abdominal pain. These symptoms can negatively affect their daily life and behavior. Recent research suggests that the gut microbiota-the community of bacteria and other microorganisms living in the intestines-plays an important role in digestion, immunity, and communication with the brain through the gut-brain axis. Modifying the gut microbiota may help improve GI symptoms and possibly behavioral functioning.

FMT involves giving a preparation containing gut microbiota from a healthy donor after bowel cleansing. The product used in this study is MBiotix HBI Caps, produced by Human Biome Institute. A placebo (inactive substance) will also be used for comparison. Both will be given as frozen oral capsules that look identical.

20 children aged 6-12 years will take part. Participants will be randomly assigned to receive either the microbiota preparation or placebo. The study includes several visits over about 6 months. Before the first dose, every child will undergo bowel cleansing with a special preparation (Polyethylene Glycol, PEG). During the study, participants will be asked to keep a symptom diary, complete questionnaires, and record child's diet. Biological samples (stool, urine, saliva) will be collected at specific time points for analysis. Every child will also be assessed by a psychologist before the study begins and again during the study using standardized tools (Autism Diagnostic Observation Schedule, Second Edition, ADOS-2) to evaluate behavioral functioning and quality of life.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

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 (Estimated)

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.
20

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.
  • Not Applicable

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

  • Poland
    • Masovian Voivodeship
      • Warsaw, Masovian Voivodeship, Poland, 01-211
        • Institute of Mother and Child

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

  • Child

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Providing informed consent for participation in the study by the child's legal representative - parent or legal guardian.
  • Diagnosis of autism spectrum disorder according to DSM-5 or ICD-11 criteria.
  • Ability to swallow an empty test capsule identical in shape and size to the investigational product
  • Abnormal stool consistency observed by parents for at least 2 months prior to study inclusion.

Patients with an average stool consistency greater than 5 on the Bristol Stool Form Scale (BSFS) during the baseline period will be classified as having diarrhea.

Patients with an average stool consistency less than 3 on the Bristol Stool Form Scale during the baseline period will be classified as having constipation.

Exclusion Criteria:

  • Presence of a gastrointestinal disease such as celiac disease, food allergy, inflammatory bowel disease, pancreatitis, chronic liver disease, eosinophilic esophagitis, peptic ulcer disease of the stomach or duodenum, Hirschsprung's disease.
  • Primary or secondary immunodeficiency, including absolute neutrophil count in peripheral blood <1500 measured within 28 days prior to planned FMT.
  • History of surgery involving disruption of intestinal continuity within 3 months prior to study inclusion.
  • Lactose or fructose intolerance. Patients with lactose intolerance who follow an elimination diet and still experience symptoms may be included in the study.
  • Malnutrition defined as Body Mass Index (BMI) below the 3rd percentile based on Polish growth charts from 2010.
  • Overweight or obesity defined as BMI above the 85th percentile based on Polish growth charts from 2010.
  • Active infection requiring antibiotic therapy.
  • Expected use of antibiotics during participation in the study.
  • Use of probiotics during participation in the study.
  • Inability to undergo bowel cleansing therapy (Dicopeg Endo).
  • Inability to swallow an empty test capsule.
  • Lack of consent from the child's legal representative - parent or legal guardian - for participation in the study.

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: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

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.
Placebo Comparator: Placebo
Other: Placebo
Placebo
Experimental: MBiotix® HBI Caps
Other: MBiotix® HBI Caps

MBiotix HBI Caps (Human Biome Institute, Poland) are enteric-coated capsules containing a concentrated suspension of gut microbiota obtained by centrifugation of a solution prepared from 60 g of donor stool suspended in 200 ml of 0.9% NaCl and glycerol. Each capsule set contains approximately 10¹³ viable bacterial cells.

Dosing depends on body weight:

Children weighing **>35 kg** will receive 60 g at visit 1 and 30 g at visits 2 (after 4 weeks) and 3 (after 8 weeks).

Children weighing **<35 kg** will receive 30 g at visit 1 and 15 g at visits 2 (after 4 weeks) and 3 (after 8 weeks).

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
Number of patients who showed an improvement in stool consistency by at least 1 point on the Bristol Stool Scale compared to the baseline period.
Time Frame: 4,8,9,12,26,20 weeks
The average stool consistency will be calculated from the one-week baseline period and from weekly observation periods during the study.
4,8,9,12,26,20 weeks

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
Bowel movements
Time Frame: 4,8,9,12,16,20 weeks
Change in the number of bowel movements compared to the baseline period.
4,8,9,12,16,20 weeks
Abdominal pain episodes
Time Frame: 4,8,9,12,16,20 weeks
Change in the number of abdominal pain episodes compared to the baseline period.
4,8,9,12,16,20 weeks
Days with abdominal pain
Time Frame: 4,8,9,12,16,20 weeks
Change in the number of days with abdominal pain compared to the baseline period. Endpoints assessing abdominal pain will be evaluated only in children who are able to communicate their symptoms.
4,8,9,12,16,20 weeks
Excessive gas
Time Frame: 4,8,9,12,16,20 weeks
Change in the number of days with excessive gas according to parent's assessment.
4,8,9,12,16,20 weeks
Regurgitation
Time Frame: 4,8,9,12,16,20 weeks
Change in the number of days with regurgitation compared to the baseline period.
4,8,9,12,16,20 weeks
Vomiting
Time Frame: 4,8,9,12,16,20 weeks
Change in the number of days with vomiting compared to the baseline period.
4,8,9,12,16,20 weeks
Child absence
Time Frame: 4,8,9,12,16,20 weeks
Change in the number of days absent from kindergarten or school due to symptoms.
4,8,9,12,16,20 weeks
Parent's work absence
Time Frame: 4,8,9,12,16,20 weeks
Change in the number of days of parental or caregiver work absence due to symptoms
4,8,9,12,16,20 weeks
Adverse events
Time Frame: 0,4,8,9,12,16,20 weeks
Adverse events reported by children and parents, recorded in the symptom diary and reported to the physician.
0,4,8,9,12,16,20 weeks
SRS-2
Time Frame: 9,20 weeks
Change in the score of the psychological test Social Responsiveness Scale-2 (SRS-2) compared to baseline.
9,20 weeks
ASRS
Time Frame: 9,20 weeks
Change in the score of the psychological test Autism Spectrum Rating Scales (ASRS) compared to baseline
9,20 weeks
ADOS-2
Time Frame: 9,20 weeks
Change in the score of the psychological test Autism Diagnostic Observation Schedule-2 (ADOS-2) compared to baseline.
9,20 weeks
CBCL
Time Frame: 9,20 weeks
Change in the score of the psychological test Child Behavior Checklist (CBCL) compared to baseline.
9,20 weeks
ABAS-3
Time Frame: 9,20 weeks
Change in the score of the psychological test Adaptive Behavior Assessment System-3 (ABAS-3) compared to baseline.
9,20 weeks
QoLA
Time Frame: 9,20 weeks
Change in parental quality of life assessed using the Quality of Life in Autism Questionnaire (QoLA) compared to baseline.
9,20 weeks

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.
Institute of Mother and Child, Warsaw, Poland

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.
Human Biome Institute S.A.

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 (Estimated)

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.
January 1, 2026

Primary Completion (Estimated)

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.
December 1, 2026

Study Completion (Estimated)

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.
March 1, 2027

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).
January 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.
January 22, 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.
January 27, 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.
January 27, 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.
January 22, 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.
December 1, 2025

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.
  • 12/2025

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

IPD used in the results publication

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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