Critical Role of the Gut Microbiota in Prunes’ Prevention of Glucocorticoid Induced Osteoporosis

This work investigates the critical role of the gut microbiota in mediating the protective effects of dietary prune (dried plum) supplementation against glucocorticoid-induced osteoporosis (GIO). Glucocorticoids are widely used anti-inflammatory drugs whose chronic use causes significant trabecular bone loss and increases fracture risk. Previous research has established that chronic glucocorticoid treatment disrupts gut microbial community composition (dysbiosis) and that microbiota alterations can contribute mechanistically to bone loss. Prunes are a natural prebiotic rich in fiber, antioxidants, and phenolic compounds and have been reported to prevent and even reverse sex-steroid deficiency–induced bone loss in rodent models and to alter gut microbiota composition in animals and humans. Building on these observations, the authors tested whether dietary prune (DP) supplementation could prevent GC-induced bone loss and whether such protection is associated with changes in gut microbiota.

Using an established mouse model of GIO, skeletally mature 16-week-old female C57BL/6J mice received either placebo or subcutaneous prednisolone pellets for eight weeks and were fed a control diet or diets containing 5%, 15%, or 25% (w/w) dried California prune powder. As anticipated, glucocorticoid-treated control-diet mice developed significant trabecular bone loss in the distal femur. Remarkably, even the lowest prune concentration tested (5% DP) effectively prevented trabecular bone loss in glucocorticoid-treated mice. Dose-dependent improvements were observed, with 15% and 25% DP supplementation producing progressively greater increases in trabecular bone volume fraction in glucocorticoid-treated animals. Unexpectedly large effects were also observed in non–glucocorticoid-treated (placebo) mice: 25% DP supplementation in healthy mice produced approximately a threefold increase in distal femur trabecular bone volume fraction, a magnitude of anabolic bone response not previously reported for gut-targeted natural treatments in healthy rodents.

Concomitant with bone effects, glucocorticoid treatment and high-dose DP supplementation elicited pronounced shifts in gut microbiota composition. Several specific microbial changes were strongly associated with bone health measures, supporting the concept that prune-mediated modulation of the gut microbiome contributes to skeletal protection. The study frames prune as a prebiotic intervention that can both prevent glucocorticoid-driven bone deterioration and elicit substantial bone anabolic responses under some conditions, with these skeletal outcomes tightly linked to shifts in the intestinal microbial community.

These findings position dietary prune supplementation as a promising, natural, nonpharmacologic strategy to mitigate the adverse skeletal effects of prolonged glucocorticoid therapy—an important clinical problem for patients who require long-term glucocorticoid treatment and cannot discontinue therapy. The results also emphasize the gut microbiota as a tractable target for osteoporosis prevention and underscore the need for further mechanistic work to identify specific microbial taxa or metabolites that mediate prune’s bone-protective effects, dose–response relationships, and translational studies to evaluate whether similar benefits occur in humans receiving chronic glucocorticoids. Overall, Chargo and colleagues provide compelling preclinical evidence that dietary prunes can prevent GIO and that modulation of the gut microbiota is a central component of this protective effect.