The gut–bone axis: microbial metabolism and nutritional interventions for bone health

Osteoporosis is a prevalent condition characterized by a rapid decline in bone mineral density and distorted microarchitecture, which leads to increased bone fragility. The gut microbiota and its metabolites play a crucial role in the development and progression of osteoporosis by influencing gut permeability, nutrient digestion and absorption, pH balance, and immune regulation. Nutritional interventions aimed at modulating gut microbiota, through postbiotics (butyrate), probiotics (Bifidobacterium animalis or Lacticaseibacillus rhamnosus LGG), prebiotics (fructo-oligosaccharides), synbiotics, and specific dietary patterns (e.g. Mediterranean and vegetarian diets) have emerged as promising strategies to mitigate bone loss associated with aging. This review investigates the communication between the gut and bone, summarizing the underlying mechanisms and providing an updated review on microbial metabolites. Additionally, it examines recent research on probiotics and their metabolic contributions, highlighting potential gaps in the current understanding of this field.