Abstract
Due to the increasing incidence of individuals with metabolic syndrome and the higher correlations between metabolic syndrome and the gut microbiota, there is a need to formulate functional foods that can promote the
development of beneficial microorganisms within the gut microbiota. This study aims to evaluate the possible positive effects of innovative gluten-free flatbread, containing grape
and apple antioxidant-rich by-products, on the gut microbiota of patients with metabolic syndrome. The baked products were subjected to gastric digestion using the Infogest system, followed by proximal colonic fermen-
tation in the MICODE (Multi-Unit In vitro Colon Model) intestinal model, where three samplings were performed (baseline, after 16 h and 24 h). The samples were then subjected to 16S rRNA metataxonomy, quantification of
shifts in bacterial populations by qPCR analysis and characterization of volatile organic compounds by SPME GC–MS (Solid Phase Micro Extraction Gas-Chromatography Mass-Spectrophotometry). A robust statistical
approach based on several tests and multivariate analysis was applied. The results obtained demonstrated the in vitro potential of functional flatbreads in improving the dysbiosis of the microbiota of individuals with metabolic
syndrome, due to a reduction in the Firmicutes/Bacteroidota ratio, and highlighted an increase in commensal microorganisms (Bifidobacterium, positive clostridia and Akkermansia muciniphila) and a reduction in negative
microorganisms (Enterobacteriaceae, negative clostridia and Collinsella spp.). The analysis of metabolites showed an increase in health-beneficial metabolites (acetate and medium chain organic acids) and a reduction in harmful
metabolites (p-cresol and skatole), the degree of this modulation varied based on the flatbread composition. While this study employed an in vitro model of recognized limitations, it nonetheless provides valuable,
evidence-based results that can be used for preclinical screening of formulations. Anyhow this work is of high fashion in this running time as it proposes i) in vitro models rather than animal testing; ii) human MetS gut
microbiota for high translatability to in vivo condition; iii) approaches of precise and personalized nutrition by the use of specific microbiota and omic technologies, all component that vow to be the future of food assessment.