Narrative review examines probiotic-fortified foods versus conventional supplementation for gut and metabolic health.

Foods fortified with probiotics are a fast-emerging field at the crossroads of food technology, nutritional biochemistry and microbiome science. The increased interest in the gut microbiota as a key controller of host metabolism, immunity and overall homeostasis has led to the creation of diets that provide key nutrients with live and beneficial microbes. Compared to the conventional dietary supplementation, there are improved microbe stability, bioavailability, and microbe-nutrient interactions of probiotic fortification of food matrices. This review is a summary of the literature on the impact of probiotics on the host immunological and metabolic signalling pathways, intestinal barrier functioning, and gut microbiota composition. The biological mechanisms of interaction of probiotics with the intestinal microenvironment are specifically focused on the production of short-chain fatty acids, expulsion of pathogens, the regulation of immune cells, and the communication of the gut-brain axis. New information that can be used to correlate the administration of probiotics with the improvement of gastrointestinal health, systemic inflammation, metabolic maintenance and neurobehavioral phenotypes is narratively synthesized based on available preclinical and clinical evidence. The opportunities of probiotic-enriched functional foods have been highlighted in this review as a strategic tool of disease prevention and health promotion in the context of the mechanistic knowledge in combination with translational health outcomes. The complexity in the interactions between microbial delivery systems and host physiology is the clue to the best efficacy, safety and the future innovation in the development of functional foods.