Gut check: do probiotics or postbiotics help during antibiotics?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: Participants meeting ALL of the following criteria will be recruited for the study: * Males and females aged ≥18 to ≤ 65 years; if female, either not of childbearing potential or using a medically approved method of birth control and willing to take a pregnancy test at screening. * Body mass index (BMI) 18.5-29.9 kg/m². * Healthy as determined by medical history and physical examination. * Agreed not to change current dietary habits during the course of the study. * Able to attend study visits, comply with study requirements (consumption of study medications, especially biological sample collection procedures, and study visit schedule) and provide reliable and complete data regarding AEs/SAEs and PROs. * Have been informed and have given written consent for the use of their data in accordance with local regulations before study inclusion. Exclusion Criteria: Participants meeting ANY of the following criteria will be excluded from the study: * Women who are pregnant, breastfeeding, or planning to become pregnant during the course of the study. * People on vegetarian or vegan diet; People on special diet (e.g. Ducan, Keto, etc.) * BMI ≥ 30 kg/m² or \<18.5 kg/m². * History of intake of antibiotics, other probiotics, postbiotics, prebiotics, synbiotics, proton pump inhibitors, acid sequestrants (cholestyramine, Bile colestipol), within six months prior to the screening day. * Participation in other clinical trials in the last 90 days prior to screening. * Allergy to any penicillin antibiotic or any other beta-lactam agent (e.g. cephalosporin, carbapenem or monobactam). * History of jaundice/hepatic impairment due to amoxicillin/clavulanic acid. * Active smokers or using any form of smokeless tobacco. * Participants with substance abuse problems (within two years) defined as: * Use of recreational drugs (such as cocaine, methamphetamine, marijuana, etc.)/ Nicotine dependence. * High-risk drinking as defined by the consumption of four or more alcohol-containing beverages on any day or eight or more alcohol-containing beverages per week for women and five or more alcohol-containing beverages on any day or 15 or more alcohol-containing beverages per week for men. * Participants having clinically significant illnesses of cardiovascular, endocrine, immune, respiratory, hepato-biliary, kidney and urinary, haematological, musculoskeletal system and/or any inflammatory disorder, tumour, and other gastrointestinal diseases. * Participants with a history of bariatric surgery or surgical resection of the stomach, small intestine, or large intestine. * Participants actively using GLP1 agonist drugs (Wegovy, Semiglutide etc.) or completed treatment with said medication less than 12 weeks before screening. * Any condition that could, in the opinion of the Investigator, preclude the participant's ability to successfully and safely complete the study or that may confound study outcomes.