From Probiotics to Postbiotics—An Update on Their Biotherapeutic Potential and the Emerging Strategies in Human Health

Probiotics and postbiotics have gained increasing attention in microbiome research due to their potential roles in maintaining gut homeostasis and supporting human health. While probiotics are defined as live microorganisms that confer health benefits when administered in adequate amounts, postbiotics represent preparations of inanimate microorganisms and/or their components that also exert biological effects on the host. This narrative review provides an updated overview of the current knowledge on probiotics and postbiotics, with a particular focus on their mechanisms of action, production strategies, and emerging applications in human health. The review discusses key mechanisms through which probiotics and postbiotics interact with the host, including modulation of the gut microbiota, enhancement of epithelial barrier integrity, immune system regulation, metabolic modulation, and systemic signaling pathways. Advances in production technologies, ranging from conventional fermentation to innovative inactivation and stabilization approaches, are also examined, alongside challenges related to yield optimization, stability, safety, and standardization. Although a growing body of evidence suggests potential benefits of probiotics and postbiotics in metabolic, inflammatory, gastrointestinal, and immune-related conditions, much of the available data is derived from preclinical studies or small-scale clinical trials. Consequently, their clinical efficacy, optimal dosing, and long-term safety require further validation. By integrating current findings and highlighting existing gaps in the literature, this review aims to clarify the therapeutic potential of probiotics and postbiotics and to support the development of more robust, evidence-based strategies for their application in functional foods, supplements, and future biotherapeutic interventions.