Modulation of Intestinal-Bone Crosstalk by a Standardised Nutraceutical Combination: An In Vitro Mechanistic Study

Background/Objectives: Natural multi-component nutraceutical formulations may modulate interconnected pathways involved in metabolic and bone health. This study evaluated, using in vitro models, the effects of a standardized botanical-vitamin formulation on intestinal barrier integrity, osteoblastic activity, and osteoclast differentiation, focusing on intestinal-bone crosstalk, redox-inflammatory signalling, and potential synergistic interactions among components. Methods: A combined in vitro approach using intestinal, osteoblastic, and osteoclastic cell models was applied to assess a formulation containing characterized plant extracts and vitamin D₃. The study evaluated cytocompatibility, intestinal barrier function, cellular uptake, and the modulation of markers related to osteogenesis and osteoclastogenesis, using biochemical, molecular, and enzymatic assays, as well as oxidative stress measurements and synergy analysis. Results: The formulation maintained intestinal barrier integrity and bioavailability without cytotoxicity, promoted osteoblastic differentiation and reduced oxidative stress, while inhibiting osteoclast differentiation and resorptive activity. These effects were associated with modulation of inflammatory and redox-related signalling pathways and showed additive to synergistic interactions among components. Conclusions: These findings support a multi-target nutraceutical approach that can concurrently influence intestinal barrier and bone remodelling in vitro, offering mechanistic evidence for its role in modulating the gut-bone axis, and highlight the need for further studies in advanced models and clinical trials.