Long-term eggshell membrane supplementation contributes to sustained bone mass by suppressing bone resorption in rats.

Eggshell membrane (ESM) supplementation enhances bone mass during skeletal growth, but its long-term effects are unclear. We investigated whether continuous ESM intake for 16 weeks supports bone health from growth to skeletal maturity in rats. Seven-week-old male Wistar rats received oral ESM for 16 weeks. Trabecular microarchitecture and marrow adiposity were assessed by micro-computed tomography and histology. Osteoblast and osteoclast parameters were evaluated by immunohistochemistry and gene expression analyses. ESM increased trabecular bone volume and improved trabecular microstructure while reducing marrow adiposity. Osteoblast numbers and osteogenic gene expression (Sp7 and Col1a1) did not differ between groups. ESM reduced adipogenic gene expression (Pparg), decreased tartrate-resistant acid phosphatase-positive osteoclast numbers and cathepsin K immunoreactivity, and downregulated osteoclast-related genes (Ctsk, Tnfsf11, and Nfatc1). Long-term ESM supplementation maintains trabecular bone volume by suppressing marrow adipogenesis and bone resorption, supporting its potential as a functional food ingredient to promote skeletal health beyond early growth.