The PRODARE (PRObiotic human study Design And Reporting) recommendations were achieved through expert consensus following a cross-disciplinary workshop convened by the Probiotics Task Force of ILSI Europe.
A spokesperson for the task force told NutraIngredients that clinical studies are essential for demonstrating the health benefits of probiotics. While general guidance exists for designing and reporting clinical trials, probiotics present unique challenges because they are live microorganisms whose viability, strain identity, stability, and dose can influence study outcomes, they said.
“The new PRODARE recommendations, developed through an ILSI Europe initiative, provide a structured framework specifically tailored to the design and reporting of human probiotic studies,” said the spokesperson. “Their goal is to improve the quality, transparency, reproducibility, and interpretation of clinical research on probiotics used in foods and dietary supplements.”
The issue
Human nutrition studies are informed by several established but generic guidelines which do not address the specific challenges associated with probiotic research.
“Consequently, researchers may encounter ambiguity when selecting appropriate study designs or when interpreting and reporting findings in a way that accurately captures probiotic mechanisms of action and associated health outcomes,” explained the ILSI Probiotics Task Force in Advances in Nutrition. “This lack of specificity compromises the reproducibility, comparability, and, ultimately, the scientific and regulatory legitimacy of study findings.”
To address this, a workshop was held at ILSI Europe in Brussels in April 2025 produced a consensus-based conceptual framework and a decision tree for improving the reliability, rigor, and comparability of probiotic studies.
The general recommendations outlined in the paper are:
1. Clearly report the strain designation
2. Studies should record the diet, lifestyle, and age of the investigation population. The authors also recommended that The Strengthening the Organization and Reporting of Microbiome Studies (STORMS) reporting guidelines be used for microbiome-related studies
3. Determine and align washout periods before and after the intervention
4. Risk management measures should be implemented to prevent cross-contamination
5. Establish and use core outcome sets (COSs) to ensure consistent endpoints
6. Reporting on probiotic dosage and live cell count should be standardized
7. Studies should be registered to avoid duplication, qualify for publication, and ensure transparency
Five main study types were then identified by the experts, including exploratory studies, pilot studies, randomized controlled trials, real-world studies, and observational cohort studies.
“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,” wrote the expert working group in Advances in Nutrition.
“These recommendations aim to enhance study quality and reporting and to guide researchers in selecting study designs appropriate to their objectives.”
The authors recommended that the PRODARE recommendations be aligned with existing international initiatives, such as the COMET Initiative, in order to promote formal recognition of probiotic-specific methodological guidance and accelerate the translation of research into evidence-based practice and policy.
The full Open Access paper is available in Advances in Nutrition.
Source: Advances in Nutrition. 2026, doi: 10.1016/j.advnut.2026.100668. “Probiotic Human Study Design and Reporting (PRODARE): Recommendations to Improve Research Practice”. Authors: H. Szajewska, et al.
