Gut Microbiota as a Molecular Regulator of Mineral Homeostasis in Horses: Mechanisms and Future Perspectives

Mineral homeostasis in horses is traditionally attributed to the coordinated regulation of the intestine, kidneys, skeleton, and endocrine system. Emerging evidence suggests the gut microbiota also shapes this process by modifying the intestinal environment where mineral absorption occurs. Despite the growing interest in host–microbiota interactions, the mechanisms linking the equine gut microbiota to mineral metabolism remain poorly understood and have not been comprehensively synthesized. This review integrates current knowledge of equine gastrointestinal physiology, gut microbial ecology, and mineral metabolism to examine how the gut microbiota influences mineral homeostasis, focusing on microbial fermentation, bioactive metabolite production, luminal pH regulation, epithelial barrier integrity, modulation of intestinal mineral transporters, and interactions with endocrine and immune pathways. The assessment of macro minerals such as calcium, phosphorus, and magnesium, along with trace minerals like iron, zinc, copper, selenium, and manganese, was conducted with a critical approach. This evaluation differentiates between results derived from equine research and those inferred from studies on other species. However, direct mechanistic evidence in horses remains limited, highlighting the need for future research. Advancing equine microbiome research through integrated microbiome profiling, metabolomics, molecular biology, and mineral balance studies will improve our understanding of host–microbiota interactions and support microbiome-informed nutritional strategies to enhance mineral utilization, gastrointestinal health, skeletal function, and long-term equine health and performance.