During a IPA Europe conference, recently held in Brussels, Microbiomepost sat down with Ger T. Rijkers (University College Roosevelt, the Netherlands) to discuss the regulatory frame about probiotics in Europe.

Probiotic research is frequently constrained not by lack of scientific interest, but by the difficulty of generating evidence that satisfies the European Food Safety Authority (EFSA) for authorized health claims. 

From a regulatory standpoint, the first obstacle is trial design: the intended benefit must be matched to an appropriate target population and measurable endpoints. Claims framed around prevention or risk reduction in healthy individuals often require very large cohorts and long follow-up to demonstrate a statistically and clinically meaningful effect, making such studies logistically and financially prohibitive. By contrast, efficacy may be more feasibly demonstrated in well-defined patient populations with established gastrointestinal conditions (for example, inflammatory bowel disease), after which the relevance of these findings to broader preventive contexts can be explored.

According to Rijkers, a second obstacle is conceptual. EFSA’s assessment model has historically been better suited to single, well-characterized molecules (e.g., vitamins) with clearer mechanistic links to host receptors and pathways. Probiotics, as live microorganisms, act through multiple interacting components and indirect host responses, which complicates mechanistic substantiation and evidence integration. Finally, probiotics are regulated as foods and supplements rather than drugs, which shapes expectations around study settings and participant selection and can limit the types of trials that are considered acceptable. Although EFSA authorization is theoretically attainable, a long record of negative opinions—combined with limited prescriptive guidance and reliance on case-by-case evaluation—creates substantial uncertainty for dossier development and clinical strategy, suggesting that progress will require not only stronger evidence but also clearer regulatory direction.