Probiotic Human Study Design and Reporting (PRODARE): Recommendations to Improve Research Practice

The PRObiotic human study Design And REporting recommendations provide a structured framework for designing and reporting human studies with probiotics, addressing challenges related to product viability. Five main study types are identified. Exploratory studies are early-phase, first-in-human investigations designed to evaluate effects or generate hypotheses and require specification of strain, dose, stability, and assessment of acceptance and adverse events. Pilot studies assess the feasibility of protocols and logistics before larger trials, with clearly defined objectives, compliance measures, and data management plans. Randomized controlled trials represent the reference standard for evaluating efficacy and safety and include the use of core outcome sets, blinding procedures, and adherence monitoring. Real-world studies evaluate effectiveness outside controlled research settings and require detailed protocols, comprehensive data capture, and predefined approaches for handling inconsistencies. Observational cohort studies examine associations between probiotic exposure and outcomes over time, with clearly defined endpoints, cohort selection criteria, and analysis plans. Across all study types, probiotic-specific considerations include strain characterization and sequencing, verification of identity, purity, viability, antimicrobial resistance, minimization of confounding factors, management of cross-contamination, and consistency of dosage. These recommendations aim to enhance study quality and reporting and to guide researchers in selecting study designs appropriate to their objectives.