Infants often experience functional gastrointestinal symptoms (e.g., colic, excessive gas, regurgitation, constipation, or loose stools) that distress families and may reflect an imbalance of the gut microbiome. This study evaluates whether the multistrain probiotic BioAmicus Complete can improve caregiver-reported gastrointestinal symptoms in infants 0-24 months and is safe for use in this population.

The primary assessment is the change in the Infant Gastrointestinal Symptom Questionnaire (IGSQ) total score from the start to the end of the study period. Secondary assessments include symptom domains (colic/regurgitation, stool frequency and consistency), caregiver quality of life, growth parameters (weight and length), health care utilization and antibiotic exposure, and overall safety/tolerability (adverse events and serious adverse events). Stool samples will be analyzed to explore changes in the gut microbiome.

caregiver burden and health care visits. Modulating the developing gut microbiome with probiotics may alleviate these symptoms. BioAmicus Complete is a multistrain probiotic designed to support a healthy intestinal microbiota; systematic clinical evaluation is warranted to determine its efficacy and safety in infants.

Objectives:

Primary: Determine whether BioAmicus Complete improves overall gastrointestinal symptoms versus usual care, measured by change in IGSQ total score between baseline and study end.

Exploratory (microbiome): Characterize changes in stool microbiome composition and diversity across the study period.

Secondary: Compare groups on symptom domain scores (e.g., colic, regurgitation, stooling patterns), caregiver burden/quality of life, health care utilization and antibiotic exposure, growth parameters, and safety outcomes (adverse events, serious adverse events, and product-related events).

Significance: Findings will inform whether BioAmicus Complete can be recommended as an adjunct to routine care for infant functional gastrointestinal symptoms and will provide preliminary insights into microbiome changes associated with symptom improvement.

Inclusion Criteria:

• Age 0-24 months at enrollment.
• Infant has clinician-assessed functional gastrointestinal symptoms (e.g., colic/irritability, regurgitation, constipation, loose stools), judged suitable for study participation.
• Parent or legal guardian provides written informed consent and agrees to comply with study procedures (questionnaires/diaries and sample collection, if applicable).
• Caregivers agree to avoid other probiotic products during the study period, except as directed by the study team.

Exclusion Criteria:

• Major congenital gastrointestinal anomalies or known chronic gastrointestinal diseases requiring ongoing prescription therapy (e.g., Hirschsprung disease, inflammatory bowel disease, short-bowel syndrome).
• Clinically unstable condition or severe/critical illness that could interfere with participation or safety in the opinion of the investigator.
• Known or suspected primary or secondary immunodeficiency, or current immunosuppressive therapy.
• History of severe allergy or hypersensitivity to components of the investigational product.
• Recent use of systemic antibiotics within 14 days prior to baseline, or use of probiotic supplements within 14 days prior to baseline (per protocol).
• Participation in another interventional clinical trial within 30 days prior to enrollment or during the study.
• Any condition that, in the investigator's judgment, would make the participant unsuitable for the study or confound outcome assessments.

De-identified individual participant data (IPD) underlying the primary and secondary outcomes will be shared. Datasets will include: baseline characteristics; IGSQ item and total scores; caregiver diary data (stool frequency/form, regurgitation/vomiting counts, crying/irritability duration); growth parameters; concomitant medications; protocol deviations; and safety data (TEAEs/SAEs, relatedness, severity). For microbiome analyses, processed data (e.g., feature/ASV tables, relative abundance matrices, and diversity indices) will be shared; raw sequencing reads may be available on justified request. A data dictionary and variable codebook will accompany the IPD.

IPD and supporting materials will become available ~6 months after publication of the primary results and will remain available for 36 months thereafter. Earlier access may be granted for bona fide regulatory or public health needs. Extensions beyond 36 months will be considered upon reasonable request.

Access is available to qualified researchers with a methodologically sound proposal and, where applicable, IRB/ethics approval or waiver. Submit requests to the study contacts listed in this record, including a brief proposal and analysis plan. Approved requestors must sign a Data Use Agreement; data will be provided via secure transfer. Data may be used only for the approved objectives; re-identification is prohibited; citation of the original study is required; data must be destroyed or returned at the end of the access period.