Probiotics are defined as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host” (2). These beneficial bacteria and yeasts, primarily from the Lactobacillus, Bifidobacterium and Saccharomyces genera, are essential for maintaining gut microbiota balance, supporting digestive health, and modulating immune function. Their applications extend beyond gastrointestinal benefits, with increasing evidence suggesting systemic health effects. Consequently, probiotics are widely incorporated into functional foods, food supplements, and medical products, aligning with the growing consumer demand for evidence-based dietary and lifestyle solutions.

The growing interest in microbiome science has fuelled a surge in research on probiotics, leading to a deeper understanding of their role in human health. In 2024 alone, the International Scientific Association for Probiotics and Prebiotics (ISAPP) reported that over 10,000 papers were published on biotics and fermented foods, with approximately 30,000 publications in the broader field of microbiome science (3). This expanding body of evidence underscores the scientific community’s investment in understanding the complex interactions between probiotics and the human microbiome.

Despite their rising popularity, the term probiotic is often used inconsistently, with many commercially available products failing to meet scientific criteria regarding strain identity, safety, and efficacy (4, 5). Regulatory inconsistencies and varying substantiation requirements further complicate global commercialization and consumer education, creating challenges for both industry stakeholders and public health authorities. Addressing these concerns through standardized definitions, stringent quality controls, and harmonized regulations is critical to ensuring the credibility and effectiveness of probiotic products in the marketplace.

Substances without a history of safe use in the European Union (EU) before 1997 are subject to the Novel Food Regulation. This regulation requires a comprehensive safety assessment by the European Food Safety Authority (EFSA) before market authorisation. For new probiotic substances, this may involve:

• Toxicological studies
• Allergenicity assessments
• Nutritional evaluations

EFSA introduced the concept of Qualified Presumption of Safety (QPS) to standardise a generic pre-assessment to support safety risk assessments. The QPS assessment is conducted separately from and independently of the safety assessment of a regulated product submitted for market authorisation. Therefore, having QPS status does not guarantee market authorisation. Nonetheless, if a product that requires a pre-market authorisation contains a microbial species that has QPS status, a simplified safety assessment may be done, that involves less data on potential risks as compared to a product containing a microbial species without QPS status (6). EFSA performs an extensive literature search and then updates the QPS list every 6 months. It is important to note that the GRAS status of ingredients, including microbes, has no regulatory status in the EU.

Safety Assessment

Safety remains the paramount concern for new probiotic strains for use in food supplements. EFSA has established stringent criteria for safety assessment:

• Long history of safe use in food or supplements without substantiated harm reports in healthy individuals
• Rare or isolated credible reports of infection or intoxication, limited to high-risk populations
• Organism identifiable to at least species level
• Availability of antimicrobial agents for treating potential infections
• Evidence of absence of biogenic amine production capacity

These criteria form the foundation for evaluating the safety of new probiotic strains, ensuring consumer protection while allowing for innovation in the supplement industry.

Strain Characterization and Storage

Proper characterization and storage of probiotic strains are essential to maintaining their safety, stability, and efficacy. Probiotic ingredient and supplement producers must ensure:

• Culture deposition in a recognized and accessible collection for traceability
• Storage of the master cell bank at -80°C to preserve strain integrity and prevent genetic drift
• Characterization of the organism at defined intervals to confirm strain identity and detect any genetic or microbial contamination
• Storage of freeze-dried powder ingredients under controlled conditions (e.g., low humidity, appropriate temperature) to maintain viability and potency

These measures ensure the consistency, purity, and effectiveness of probiotics throughout the production and shelf life of the product.

Production Process and Quality Management

It is essential that manufacturers of food supplements containing probiotics adhere to stringent quality control measures to ensure product consistency, safety, and efficacy. Key requirements include:

• Preservation of Microbial Integrity – The production process must not cause substantial changes to the properties of the microorganism(s) from the start of production to the final product, ensuring strain viability, stability, and intended functionality
• Adherence to Good Manufacturing Practices (GMP) – Manufacturing must comply with established GMP standards, incorporating rigorous quality assurance protocols at every stage, from raw material sourcing to final packaging
• Defined Shelf-Life and Stability Conditions – Comprehensive stability studies must be conducted to establish appropriate storage conditions that preserve microbial viability throughout the product’s shelf life
• Transparent and Accurate Labelling – Labels must clearly specify the minimum effective dosage, viable cell count (CFU) at the end of shelf life, storage recommendations, and verifiable health claims supported by scientific evidence
• Contamination Prevention and Quality Control – Regular testing must be conducted to ensure the absence of contaminants, including unwanted microbes, allergens, or environmental toxins, safeguarding product purity

These measures collectively ensure the consistent quality, safety, and efficacy of food supplements containing probiotics, providing consumers with reliable and effective products.

Probiotic Claims and Scientific Evidence

While the term "probiotic" remains contentious in EU regulations, scientific consensus has emerged regarding the requirements for probiotic claims:

• Safety assessment as a prerequisite
• Demonstration of strain viability (through appropriately designed stability studies)
• Randomized Controlled Trials (RCTs), observational studies, systematic reviews, or meta-analyses supporting general health benefits

These requirements ensure that claims are substantiated by robust scientific evidence. However, the EU’s regulatory framework presents significant challenges for the probiotic industry, particularly concerning health claims and product labelling. Under Regulation (EC) No 1924/2006 on nutrition and health claims made on foods, the European Commission considers the term "probiotic" as implying a health benefit, thereby classifying it as a health claim. To date, the European Food Safety Authority (EFSA) has not approved any health claims related to probiotics, resulting in restrictions on their use in marketing and labelling. Consequently, companies often resort to alternative terminology, such as "live cultures" or "fermented foods," to indicate the presence of beneficial microorganisms while adhering to regulatory requirements (7).

This regulatory stance has led to inconsistencies across EU member states. Italy, Spain, France, Denmark, Poland, Bulgaria, the Czech Republic, Greece, Malta, and the Netherlands have now authorised the use of the term "probiotic" on supplement labels, either as a reference to their nutritional or physiological effects, or as a category name. While this is a positive step, it adds to creating a fragmented market and potential confusion for consumers. The lack of harmonization underscores the need for a unified EU approach to probiotic labelling and health claims, balancing consumer protection with industry innovation. Harmonization will also simplify compliance for manufacturers and promote the free movement of goods within the EU market.

Regulatory approaches to probiotics also vary significantly across global markets, creating challenges for both industry stakeholders and consumers. The EU, under the oversight EFSA, maintains one of the most stringent regulatory stances, effectively prohibiting the use of the term “probiotic” in health claims. In contrast, other regions, including the United States (US) and the Asia-Pacific (APAC) markets, adopt more flexible frameworks, allowing for greater market accessibility and consumer awareness of probiotic benefits.

The US, regulated by the Food and Drug Administration (FDA) and the Federal Trade Commission (FTC), follows a more flexible regulatory pathway. Probiotics can be marketed as dietary supplements, functional foods, or medical foods, depending on their intended use and claims. The FDA does not require pre-market approval for dietary supplements containing probiotics, provided that manufacturers comply with the Dietary Supplement Health and Education Act (DSHEA) of 1994. Health claims can be made under the structure-function framework, allowing companies to state that probiotics “support digestive health” or “promote gut microbiota balance,” provided such claims are substantiated by credible scientific evidence and include disclaimers that they are not intended to diagnose, treat, cure, or prevent any disease.

The APAC region presents a diverse regulatory landscape, with some countries adopting policies that encourage probiotic innovation. Japan, for example, has long embraced probiotics within its Foods for Specified Health Uses (FOSHU) framework, which allows approved probiotics to carry health claims related to digestion and immune support. Similarly, South Korea and China have established regulatory pathways that recognize probiotic functionality, provided companies submit scientific evidence demonstrating efficacy. Australia and New Zealand, regulated by the Therapeutic Goods Administration (TGA) and Food Standards Australia New Zealand (FSANZ), respectively, also allow the use of the term “probiotic” in marketing, provided products meet safety and efficacy standards.

The disparity in regulatory frameworks across the EU, US, and APAC markets highlights the need for greater harmonization in probiotic regulation. While EFSA’s stringent criteria prioritize scientific rigor, they also limit consumer access to probiotic information and hinder market growth. Conversely, the more flexible US and APAC approaches enable innovation and consumer choice but may raise concerns about standardization and claim validity. A harmonized global framework that balances scientific evidence with market accessibility could enhance consumer trust, support industry development, and ensure consistency in probiotic health claims worldwide (8).

The regulatory landscape for probiotics in food supplements is becoming increasingly stringent and complex. As we move through 2025, manufacturers must proactively adapt by:

• Strengthening safety assessments and quality control to meet evolving regulatory expectations.
• Investing in rigorous scientific research to substantiate health claims with robust evidence.
• Enhancing transparency in labelling and marketing to provide consumers with accurate, verifiable information.
• Staying ahead of regulatory changes by actively monitoring updates and participating in harmonization efforts.

To sustain innovation while maintaining the highest safety and efficacy standards, industry stakeholders must engage with regulatory authorities, contribute to public consultations, and advocate for science-based policies. A collaborative approach will be essential in shaping a regulatory framework that fosters both consumer protection and industry growth.

Currently, the EU’s restrictive stance on probiotic health claims has forced companies to adopt alternative descriptors, creating regulatory inconsistencies across markets. This fragmentation underscores the urgent need for a unified policy that ensures consumer clarity while supporting the responsible development of the biotics sector.

The formal concept of prebiotics was first introduced in 1995 (1) and has since been redefined as research has expanded our understanding of how prebiotics in foods and supplements contribute to health. The current scientific consensus led by the International Scientific Association for Probiotics and Prebiotics (ISAPP) defines prebiotics as "a substrate that is selectively utilized by host microorganisms conferring a health benefit" (2). However, EFSA considers ‘prebiotic’ as an implied health claim and there is no guidance in order to obtain a prebiotic health claim in Europe.

A significant challenge for European health claims in general is establishing a direct cause-and-effect relationship between the ingredient and the health benefit, a key requirement set by EFSA for health claim substantiation. A prebiotic health claim would require a further relationship established between the prebiotic-induced microbiota changes and the health benefit.

The European branch of the International Life Science Institute (ILSI) has taskforces comprised of academic and industry scientists which are active in the science of prebiotics and non-digestible carbohydrates. Activities included a monograph explaining prebiotics as well as reviews advancing their scientific knowledge (3-6) . In addition, ILSI Europe led a workshop highlighting research gaps and documentation challenges while proposing steps toward obtaining authorization for the use of "prebiotic" in future EU health claims (7).

This article discusses the current regulatory status for potential prebiotic health claims in Europe as well as the status of science knowledge that would be required to support such physiological health benefits.

The EFSA evaluates health claims according to the EU Nutrition and Health Claims Regulation 1924/2006 (8), based on: (a) clear characterization of the food or constituent, (b) defined physiological benefits, and (c) evidence of a cause-and-effect relationship. In general, EFSA has a high standard for assessing the clinical and mechanistic evidence for an ingredient health claim. To substantiate specifically a ‘prebiotic’ health claim, EFSA would require that a causal relationship between an increase in certain bacteria and a physiological benefit be established. EFSA has issued guidances for studies and clinical trials that provide the necessary documentation for health claim applications such as gut health and immunity, however, there is an absence of EFSA guidance on documenting prebiotic mechanisms and benefits. Consequently, EU member states have issued varying regulatory guidance on the use of ‘prebiotic’ and similar terms like "probiotic" in food and supplement labelling. Most member states align with the European Commission’s stance that ‘prebiotic’ is considered an implied general health claim, and thereby, may only be considered for an established prebiotic provided accompanied by an authorized health claim under Articles 13 or 14.

Although a prebiotic health claim and the prebiotic term has no guidance nor is included in the EU register of health claims, certain food ingredients recognized as prebiotic have received EFSA-approved health claims. For example, chicory inulin, well-established prebiotic, has an EC authorised health claim for improving stool frequency or digestive health (9).

Recently ISAPP have published an expert recommendation or scientific framework for the classification of compounds as prebiotics, including useful methodologies, and statistical approaches to establish causal links between selective microbiome and health effects (10). The minimum criteria needed to classify compounds as prebiotics was also addressed, such as besides clinicals performed in the host, also both the selective microbiome and physiological health effects should be demonstrated in the same trial. They also addressed topline the regulation of prebiotics and communication to consumers globally.

Furthermore, in order to facilitate the development of an EFSA scientific guidance for ‘prebiotic’ health claims, ILSI Europe hosted a workshop in 2023 with academic and industry scientists and regulatory experts who came to the following proposal for a roadmap for an EU health claim for ‘prebiotic’ (Figure 1) (7).

Figure 1. A roadmap for an EU health claim on 'prebiotic'. Adapted from Tuohy et al., 2024 (7).

Altogether, these initiatives are essential to develop both strong scientific criteria and eventually support European regulation to give credibility to prebiotic health benefits.

Initially, research on prebiotics focused on their ability to selectively stimulate the growth of gut microbes bifidobacteria and lactobacilli, and this has been documented over the decades for inulin and GOS (11). Advances in high-throughput sequencing and molecular analysis have since revealed that prebiotics can selectively enhance a broader range of beneficial microorganisms beyond these two groups (10). It is noteworthy that the ISAPP definition extends beyond oligosaccharides or fibers to include non-carbohydrate compounds like polyunsaturated fatty acids and polyphenols (2). Studies have demonstrated that certain oligosaccharides such as acacia fiber, inulin, and fructooligosaccharides stimulate beneficial microbes, including bifidobacteria and via cross feeding butyrate producers (11-13). Novel techniques such as multiplex community sequencing are being employed to gain a deeper understanding of how prebiotics influence the gut microbiota (14). Another challenge is establishing definitive links between microbiome modulation and specific health benefits, which recent recommendations can support (10).

However, another key aspect to advance regulatory approval, is well-designed clinical trials with outcomes assessed by validated and robust methodologies and plausible mechanisms for such benefit. Some promising benefit fields are discussed below.

Digestive Health: EFSA has outlined scientific requirements for substantiating digestive health claims, including those related to bowel function, gastrointestinal comfort, and nutrient digestion. Acceptable measures include validated symptom questionnaires and biomarkers (15). Numerous studies have shown that inulin-type fructans can stimulate bifidobacteria growth and bacterial biomass, enhance short chin fatty acid (SCFA) butyrate levels, due to gut bacterial cross-feeding by butyrate producing microbes such as Faecalibacterium prausnitzii (3, 11). Chicory inulin has an authorised health claim for increasing stool frequency, and EFSA made the mechanistic link that it was caused by enhancing bacterial fermentation and fecal bulk (9).

Some other dietary fibers have EC health claims for improving bowel habit, for example, sugar beet fiber (16), as well as the disaccharide lactulose, which accelerates intestinal transit by increasing osmotic pressure and acidifying the colon (17). While there is evidence for various dietary fibers/ingredients for improving digestive health, they may lack documented selective effects on the gut microbiota or may improve digestion by alternative noon-microbiota mechanisms and thus may not comply with the prebiotic definition.

Metabolic Health: The potential metabolic benefits of (candidate) prebiotics have been explored in animal and human studies. Research is intensifying in this field currently due to the use of medications such as GLP-1 receptor agonists for diabetes and obesity. It is noteworthy that non-digestible carbohydrates like FOS and galactooligosaccharides (GOS) have approved EC claims related to lowering blood glucose (18). Human studies have shown that diets high in inulin-type-fructan (ITF)-rich vegetables increase satiety and reduce cravings, contributing to reduced nutrient intake and weight loss in people with obesity (19, 20). Recently a systematic review and meta-analysis supported improved weight management outcomes for chicory ITFs (21). Various mechanisms are implicated such as the SCFA production site in the body, i.e. the proximal versus the distal colon, but also the impact of SCFA or the altered gut microbiome on the hormones in the body, such as GLP-1, PYY, ghrelin amongst others, which may influence metabolic outcomes (22). Despite promising results, a direct causal link between prebiotic or dietary fiber-induced microbiome changes and improved metabolic markers remains unproven, necessitating further research.

Immune Health: Dietary fibers and prebiotics may influence immune function both directly but also indirectly through microbiota-mediated mechanisms. In vitro and animal studies suggest that certain dietary fibers and prebiotics enhance immune responses by at least the following mechanisms: (a) increasing SCFA production during fermentation and SCFA are implicated in stimulating immunity (23); (b) modulating Toll-like receptor (TLR) signalling e.g., pectin inhibiting TLR-2 (24); and (c) demonstrating immune-modulating effects influenced by chain length, e.g., for inulin-type fructans in human vaccination trials (25, 26). However, challenges in human studies persist due to interindividual variability in immune responses due to ingredients, and perhaps more so for prebiotic-modulated microbiota effects. EFSA has guidance for defence against pathogens as well as beneficial change in response to allergens, though there are no validated biomarkers of the immune effect of dietary interventions except for vaccination trials (15).

Cognitive and Mental Health: Research on the gut-brain axis has spurred interest in prebiotics for cognitive function. There has recently been a thorough review on the evidence of prebiotics to promote cognitive functioning, as well as highlighting the knowledge gaps and proposing recommendations to progress this field (4). Most findings so far arise from animal models and or in vitro studies, while the number of human studies to date remains limited. Nevertheless, there is some evidence to give just two examples. A recent study demonstrated that the 12-week intake of prebiotic ITFs in healthy twins aged 60 years or above resulted in improved cognitive function, particularly in relation to associative learning and memory (27). Another human study showed that GOS consumption produced cognitive benefits in medicated psychosis patients (28). Much evidence has shown that organic acids and other microbial metabolites produced by intestinal bacteria, can cross the blood-brain barrier and may exert neuroprotective and anti-inflammatory effects important for brain health (29). There is a risk that human cognitive tests used in prebiotic research may lack sensitivity to nutritional effects, however technologies such as functional Magnetic Resonance Imaging (fMRI) with mental assessments can support trials in this field.

There will undoubtedly be significant fundamental developments in emerging prebiotic benefit areas, particularly with the rapidly evolving fields of gut-lung, gut-liver, gut-immune-brain and skin health axes (10, 30, 31). To ultimately establish prebiotic health claims in Europe, high-quality randomized controlled trials (RCTs) are essential for demonstrating clear cause-and-effect relationships. These trials should be supported by robust statistical analyses, and artificial intelligence and machine learning technologies applied to in vitro models or trial data can help confirm, for example, that microbiome modulation is causally linked to specific health benefits. A current challenge in achieving prebiotic health claims is the lack of universally accepted biomarkers, particularly in areas like immunity and intestinal health. Additionally, individual variability in microbiota responses to dietary interventions can confound outcomes, making it difficult to generalize results. Strategic cross-disciplinary collaboration and partnerships, in academic fields and with the industry, is vital to address these challenges. Approaches involving machine learning, metagenomics, and metabolomics to analyze complex datasets from microbiota and human samples, may facilitate identification of biomarkers, and the prediction of individual microbiota responses and thus potential outcomes of human interventions. This could also facilitate the development of personalized nutrition strategies based on an individual’s gut microbiota composition or blood markers, which would be essential for optimizing prebiotic interventions and securing health claims (10, 30).

Navigating the regulatory landscape to achieve authorization for prebiotic health claims is essential for the industry as solid scientific evidence and substantiated claims in Europe will give consumer trust for foods and beverages with these claims. It is important that the academic community are in accordance with the science. In addition, educating consumers about the regulatory approved benefits of prebiotics through marketing and informational campaigns can build trust for prebiotic products. Ultimately, these strategies along with innovations in research and technologies, will be critical in advancing prebiotic health claims for better health.

In the scientific community, ‘prebiotic’ is well defined and accepted, and certain ingredients comply to the prebiotic criteria of selective microbiota effects with a health benefit. Despite the clear scientific support, the EU regulatory framework doesn’t have guidance for prebiotic claims as in other regions of the world. The EU regulatory framework for health claims is challenging due to the high standards in proving direct cause-and-effect relationships for food ingredients in general to show health effects. Advancing research methodologies, harmonizing regulatory approaches, and industry investment in high-quality clinical trials to substantiate health claims are crucial for obtaining European authorized health claims for prebiotics. The scientific criteria for ‘prebiotic’ and the proposed roadmap toward the development of prebiotic-specific health claims can stimulate further discussions and activities eventually for innovative food products with scientifically proven prebiotics with health claims substantiated for the European consumers.