Evaluation of the Acceptability of a Multi-strain Probiotic Supplement (Smile Probio 45B) in Healthy Adults

January 21, 2026 updated by: Vaios Svolos, University of Thessaly

Evaluation of the Acceptability of a Multi-strain Probiotic Supplement (Smile Probio 45B) in Healthy Adults: an Open-label Pilot Study

The goal of this clinical trial is to examine the compliance and acceptability of the probiotic Smile Probio 45B in healthy adults, as well as its effect on gastrointestinal symptoms, fatigue levels, and quality of life.

Specifically, the study examines the effect of probiotic intake on improving health-related quality of life, reducing self-reported gastrointestinal symptoms such as bloating, as well as regulating stool consistency and frequency. In addition, its impact on participants' self-reported energy levels is investigated, with a particular emphasis on reducing fatigue symptoms.

Participants will:

  • take 1 capsule daily (with a main meal) during the first and second week of the intervention, and 3 capsules daily (after each main meal) during the third and fourth week of the intervention, for a total duration of 30 days.
  • complete a three-day food record on a weekly basis.
  • record their daily bowel habits, including the number of bowel movements and their consistency/form, according to the Bristol Stool Chart, which will be provided to them.
  • complete questionnaires assessing health-related quality of life [WHOQOL-BREF (World Health Organization Quality of Life)],a health status questionnaire [EQ-5D (EuroQol-5D)] and a questionnaire evaluating energy levels and fatigue [Chalder Fatigue Scale (CFQ)].
  • complete, at baseline and at the end of each intervention week a weekly symptom assessment questionnaire.
  • undergo body composition assessment at the beginning, midpoint, and end of the study.
  • complete an acceptability questionnaire at the end of the intervention.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

40

Phase

  • 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 Locations

  • Greece
    • Thessaly
      • Trikala, Thessaly, Greece, 42132
        • Recruiting
        • School of Physical Education, Sport Science and Dietetics
        • Contact:

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

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Men and women aged over 18 years
  • Body Mass Index (BMI) >18 kg/m² and <30 kg/m²
  • No use of antibiotics in the past month
  • Willingness to provide informed consent

Exclusion Criteria:

  • Pregnancy or breastfeeding
  • Age under 18 years
  • Diagnosis of a chronic autoimmune disease (e.g., Crohn's disease, ulcerative colitis, rheumatoid arthritis, psoriasis)
  • Diagnosis of type I or II diabetes
  • Current use of immunosuppressive medications
  • Current use of antibiotics or use of antibiotics within the past month
  • Current use of other supplements such as probiotics, prebiotics, or synbiotics
  • Kidney or liver disease
  • Self-reported allergy to any component of the probiotic
  • Psychological conditions affecting the ability to provide informed consent (e.g., dementia, psychosis, substance use)
  • Gastrointestinal surgery within the last 6 months

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

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Probiotic Intervention
Participants will receive probiotic supplement for 4 weeks
Dietary supplement: Probiotic
Participants will receive probiotic supplement: 1 capsule daily for 2 weeks, followed by 3 capsules daily for 2 weeks.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Daily compliance and stool consistency using the Bristol Stool Form Scale
Time Frame: From enrollment to the end of treatment at 4 weeks
Participants will record their daily compliance and stool consistency using the Bristol Stool Form Scale. Adherence to the intervention will be evaluated by recording the number of days the probiotic was consumed. To prevent potential non-compliance, participants weill be contacted via telephone on a weekly basis. At the conclusion of the study, participants will be asked to return all empty packaging and any remaining capsules.
From enrollment to the end of treatment at 4 weeks
Acceptability of the probiotic using an acceptability questionnaire
Time Frame: Immediately after the intervention
At the end of the intervention, participants will complete an acceptability questionnaire, including questions regarding ease of use of the probiotic, perceived product safety, and intention to recommend it to others.
Immediately after the intervention

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Effect of Smile Probio 45B on gastrointestinal symptoms
Time Frame: From enrollment to the end of treatment at 4 weeks
Participants will complete a weekly symptom assessment questionnaire at baseline and at the end of each week of the intervention. The questionnaire will include questions on how frequently they experienced skin reactions, headaches, changes in bowel movement frequency, nausea, diarrhea, constipation, abdominal bloating, abdominal pain, flatulence, acidic taste, and sleep difficulties. Responses will be recorded on a Likert scale (not at all = 1, rarely = 2, occasionally = 3, often = 4, and daily = 5). Higher scores mean a worse outcome.
From enrollment to the end of treatment at 4 weeks
Effect of Smile Probio 45B on fatigue levels
Time Frame: From enrollment to the end of treatment at 4 weeks

Fatigue levels will be assessed using the Chalder Fatigue Scale (CFS), which consists of 11 Likert-scale questions designed to distinguish between physical and mental fatigue. Responses will be scored using the Likert method (0-3), yielding a total fatigue score ranging from 0 to 33, with higher scores indicating greater fatigue severity.

Permission for the use of this questionnaire was requested and obtained from the respective creator.
From enrollment to the end of treatment at 4 weeks
Effect of Smile Probio 45B on quality of life using the EQ-5D-5L questionnaire
Time Frame: From enrollment to the end of treatment at 4 weeks
Quality of life (QoL) will be assessed using EQ-5D-5L, a standardized instrument for measuring generic health status, comprising five dimensions (mobility, self-care, usual activities, pain/discomfort, and anxiety/depression) and a Visual Analogue Scale (VAS). The EQ-5D-5L index score will be calculated using the validated country-specific value set, converting health states into a single index value ranging from 0 to 1, where higher values indicate better health-related quality of life.
From enrollment to the end of treatment at 4 weeks
Effect of Smile Probio 45B on quality of life using the WHOQOL-BREF questionnaire
Time Frame: From enrollment to the end of treatment at 4 weeks
Quality of life (QoL) will be assessed using the WHOQOL-BREF (World Health Organization Quality of Life-Abbreviated version), which consists of 26 items rated on a 5-point Likert scale and evaluates four domains: physical health, psychological health, social relationships, and environment, along with two items assessing overall quality of life and general health. Domain scores will be calculated and transformed to a 0-100 scale according to World Health Organization guidelines, with higher scores indicating better quality of life.
From enrollment to the end of treatment at 4 weeks

Collaborators and Investigators

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

Sponsor

University of Thessaly

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)

May 19, 2025

Primary Completion (Actual)

December 30, 2025

Study Completion (Estimated)

March 30, 2026

Study Registration Dates

First Submitted

December 15, 2025

First Submitted That Met QC Criteria

January 21, 2026

First Posted (Actual)

January 23, 2026

Study Record Updates

Last Update Posted (Actual)

January 23, 2026

Last Update Submitted That Met QC Criteria

January 21, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 25 / 28.03.2025

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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