The gut-berry axis: Current evidence and emerging insights into berry phytochemicals, probiotic fermentation, and microbiome modulation in metabolic health

The global epidemic of metabolic diseases, including type 2 diabetes mellitus, obesity, and associated cardiovascular disorders, demands innovative preventive and therapeutic strategies. Berries have emerged as promising functional foods due to their rich phytochemical content, particularly polyphenols and dietary fiber. Emerging evidence suggests that the health benefits of berries may be mediated, at least in part, through their interaction with the gut microbiome, a concept that has been termed the “gut-berry axis.” This review synthesizes current knowledge on how berry-derived bioactive compounds may modulate gut microbial composition and function, and how probiotic fermentation of berries may potentially enhance these effects. We examine the bidirectional relationship between berry phytochemicals and gut microbiota, the metabolic fate of berry polyphenols through microbial biotransformation, and the resulting production of bioactive metabolites such as short-chain fatty acids and phenolic derivatives. Special attention is given to the potential enhanced efficacy of fermented berry products, where lactic acid bacteria may biotransform native compounds into more bioavailable and potentially potent forms. The role of the gut-berry axis in improving glycemic control, lipid metabolism, and systemic inflammation is critically evaluated, with careful distinction between preclinical and clinical evidence. Furthermore, we discuss emerging strategies to optimize berry-based interventions, including targeted fermentation, encapsulation technologies, and personalized approaches based on individual metabotypes. While the evidence base is promising but preliminary, understanding the gut-berry axis may open new avenues for developing targeted dietary interventions and functional food products aimed at preventing and managing metabolic diseases.