A Phase 2 interventional study of S. boulardii CNCM (National Collection of Cultures of Microorganisms) I-745 in Autism Spectrum Disorder, sponsored by Universidad San Francisco de Quito. Active, not recruiting at 1 site in Ecuador. Open to participants aged 5 Years to 12 Years. Per ClinicalTrials.gov, last updated 2026-01-15.
Sponsored by Universidad San Francisco de Quito · Phase 2, Interventional, and Treatment
The goal of this clinical trial is to determine the effects of Saccharomyces boulardii (Sb) consumption on Ecuadorian children with a diagnosis of autism spectrum disorder (ASD) and digestive symptoms. Saccharomyces boulardii is a probiotic, in other words, a beneficial microorganism. The main question it aims to answer is: Does Sb improve intestinal health, defenses against infections, nutrition and behavior of the participants. Researchers will compare children when they are taking and not taking Saccharomyces boulardii to know if there are changes in digestive symptoms, immune system function, nutritional status and behavior. Participants will take Saccharomyces boulardii for 4 months and will be 4 months without taking Sb. All participants must provide stool, urine and blood samples. A medical, nutritional and psychological team will follow the participants at least 5 times during the study.
Autism Spectrum disorder (ASD), is a group of neurodevelopmental abnormalities that begin in early childhood, frequently characterized by problems in communication and social behavior. Metabolites produced by the gut microbiome may affect gastrointestinal (Gl) tract and central nervous system (CNS) functions supporting the presence of the gut- brain-axis. Previous studies have demonstrated changes in the intestinal microbiome in children with ASD compared with neurotypical controls. It is possible that dietary modifications, including the use of probiotics, in children with ASD could positively modify Gl and CNS functions. Few clinical studies have been carried out to assess the effects of probiotic consumption by children with ASD on their microbiota composition, intestinal function and behavior in developing countries. Consequently, the general objective of the study is to determine the effects of probiotics supplementation in gut microbiota composition, nutritional status and immune status in children with ASD.
A randomized crossover study will be conducted including children diagnosed with ASD, living within the Metropolitan District of Quito. After verifying the inclusion and exclusion criteria, 66 participants will be selected. Initially, children diagnosed with ASD will be randomly organized into 2 groups. Group A (n=33) will receive Sb supplements at a dose of 250 mg 3 times a day for a period of 4 months. While Group B (n=33) will not receive supplementation for 4 months. This will be followed by a 30-day "washout" period, during which time neither group consumes probiotics. After this time, the children's groups will change treatment for another four months. The investigators will analyze behavior, gut microbiome, metabolome, nutritional status and gastrointestinal symptoms to determine the changes caused by Sb consumption. Participants will be followed up at months 1, 4, 5, 9 10 of the study. At each follow-up, stool, blood and urine samples will be collected for the different analyzes.
A sociodemographic survey will be applied to determine the epidemiological parameters of the participants. The behavioral parameters of each child will be evaluated by means of psychological assessments. Tests that will be applied are: Autism Diagnostic Observation Schedule, Second Edition (ADOS- 2); Autism Diagnostic Interview-Revised (ADI-R); Wechsler Intelligence Scale for Children (WISC); Adaptive Behavior Assessment System (ABAS); Wechsler Preschool and Primary Scale of Intelligence (WPPSI); Battelle Developmental Inventory (BATELLE). For the evaluation of nutritional status, anthropometric measurements (weight, height, BMI) will be taken and percentiles and Z-scores will be calculated. In addition, a 24-hour recall questionnaire will be applied. Roma IV test will be applied to evaluate gastrointestinal symptoms. To determine the immunological status, the investigators will measure interleukins and growth factors in blood.
Regarding the analysis of the gut microbiota, the investigators will start with DNA extraction from stool samples. All raw sequences obtained from the Illumina sequencer will be analyzed to determine: taxonomic composition, alpha and beta diversity, functional annotation and differential microbial relative abundance between the two groups. Functional annotation will be performed using Human Microbiome Project Unified Metabolic Analysis Network (HumanN) software. Taxonomic assignment will be done using Metagenomic Phylogenetic Analysis (Metaphlan) software. Diversity metrics will be calculated using the Vegan diversity R package. To compare alpha diversity analysis, Chao 1, Shannon and Simpson's index will be calculated. For Beta diversity comparison, the Analysis of Ecological Data (ade4) function in the R package will be used to generate principal component analysis using Bray-Curtis, Jaccard, unweighted Unifrac and weighted Unifrac distance metrics. Linear discriminant analysis will be used in conjunction with the sample size effect measurement test (LEfSe) to perform differential microbial relative abundance analysis between the two groups.
The investigators will perform metabolome analysis on blood, fecal samples and urine. Metabolome assignment will be by 2D experiments based on signal in Proton nuclear magnetic resonance (H-NMR), using the human metabolome database and the biological magnetic resonance metabolome database.
1,724 studies on the registry are indexed under Autism Spectrum Disorder; 500 are open to participants now.
This study's planned enrollment of 66 is above the median of 52 across 1,368 interventional studies indexed under Autism Spectrum Disorder.
Browse Autism Spectrum Disorder studies →Universidad San Francisco de Quito is the lead sponsor of 6 studies on the registry; none are open to participants now.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Children that receive Sb supplements in the initial 4 months of the study.
Drug: S. boulardii CNCM (National Collection of Cultures of Microorganisms) I-745
Children that receive Sb supplements in the final 4 months of the study.
Drug: S. boulardii CNCM (National Collection of Cultures of Microorganisms) I-745
250 mg three times a day for 4 months
Also known as: Floratil
Modifications of gastrointestinal symptoms during Sb administration
Changes in gastrointestinal symptoms of children with ASD when they are receiving Sb. Symptoms will be evaluated with Rome IV Pediatric Questionnaire Parent Report For Children and Adolescents Age 4+.
Time frame: Gastrointestinal symptoms will be evaluated monthly, through study completion, an average of 1 year
Modifications of gastrointestinal microbiota during Sb administration
Changes in alpha diversity, beta diversity, taxonomic composition, functional annotation and differential microbial relative abundance of gastrointestinal microbiota of children with ASD when they are receiving Sb supplementation.
Time frame: Fecal samples will be analyzed at months 1, 4, 5, 9 and 10 of the study.
Modifications of fecal metabolome during Sb administration
Changes in the fecal metabolome of children with ASD when they are receiving Sb supplementation. Metabolome will be determined with 2D experiments based on signals in H-NMR, using the human metabolome database and the biological magnetic resonance metabolome database.
Time frame: Fecal samples will be analyzed at months 1, 4, 5, 9 and 10 of the study.
Modifications of blood metabolome during Sb administration
Changes in blood metabolome of children with ASD when they are receiving Sb supplementation. Metabolome will be determined with 2D experiments based on signals in H-NMR, using the human metabolome database and the biological magnetic resonance metabolome database.
Time frame: Blood samples will be analyzed at months 1, 4, 5, 9 and 10 of the study.
Modifications of urine metabolome during Sb administration
Changes in urine metabolome of children with ASD when they are receiving Sb supplementation. Metabolome will be determined with 2D experiments based on signals in H-NMR, using the human metabolome database and the biological magnetic resonance metabolome database.
Time frame: Urine samples will be analyzed at months 1, 4, 5, 9 and 10 of the study.
Modifications of body mass index (BMI) during Sb administration
Changes in the BMI of children with ASD when they are receiving Sb supplementation. To obtain BMI, weight (in kilograms) and height (in meters) will be measured.
Time frame: BMI will be determined at months 1, 4, 5, 9 and 10 of the study.
Modifications of nutrient intake during Sb administration
Changes in the nutrient intake of children with ASD when they are receiving Sb supplementation. The 24-hour reminder questionnaire will be applied to quantify nutrient intake.
Time frame: Nutrient intake will be determined at months 1, 4, 5, 9 and 10 of the study.
Modifications of immune function during Sb administration
Changes in the immune function of children with ASD when they are receiving Sb supplementation. Levels of interleukins and growth factors will be determined. Specifically, interleukin(IL)-1, IL-4, IL-6, IL-8, tumoral necrosis factor (TNF) -α, interferon (IFN)-γ, IL-10, transforming growth factor (TGF)-β will be measured.
Time frame: Blood samples for interleukins and growth factors determination will be analyzed at months 1,4, 5, 9,10 of the study
Modifications of behavior during Sb administration
Changes in the behavior of children with ASD when they are receiving Sb supplementation. ADOS- 2 test will be applied to determine conduct in different situations, sensory response and adaptive functioning. The total scores range from 15 to 60, and a higher score means a worse outcome.
Time frame: ADOS-2 test will be performed at months 1, 4, 5, 9, 10 of the study.
Modifications in the intelligence levels during Sb administration
Changes in the intelligence levels of children with ASD when they are receiving Sb supplementation. Different tests will be used according to the age and language level of the participants. WISC will be used on children from 7 years 4 months of age. WPPSI will be applied to children 7 years 3 months or younger. BATTELLE will be used for children 8 years old or younger who have a low language level. With all of these tests, a higher score means a better outcome.
Time frame: Tests will be performed at months 1, 4, 5, 9, 10 of the study.
Plan to share: Yes — Individual participant data that underlie the results reported in this article, after deidentification.
Time frame: Immediately following publication. No end date.
Access criteria: Investigators whose proposed use of the data has been approved by an independent review committee ("learned intermediary") identified for this purpose.
Started Jan 2024 (actual). Primary completion is estimated for Aug 2026, 31 months after the start.
Of 67 non-industry phase 2 interventional studies under Autism Spectrum Disorder, half reached primary completion within 39 months of starting (the median), counting those still running; a quarter within 23 and three quarters within 63. This study's planned 31 months is below that.
Counting every sponsor, half of 82 studies reached it within 36 months; a quarter within 23 and three quarters within 52.
How these figures are worked out, and which studies are left out of them.
This study is active, not recruiting, as verified in Jan 2026. You cannot join it, but the record below documents what was studied.
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Universidad San Francisco de Quito