Icariin, a flavonoid glycoside primarily extracted from the herb Epimedium (commonly known as Horny Goat Weed), has garnered scientific interest for its potential effects on the skeletal system. Preclinical studies, mostly in animal models and in vitro experiments, suggest that icariin may help promote bone formation and inhibit bone resorption. The proposed mechanisms include stimulating osteoblast activity (cells responsible for bone formation), inhibiting osteoclast activity (cells responsible for bone resorption), and modulating signaling pathways such as BMP (Bone Morphogenetic Protein) and Wnt/β-catenin, which are critical in bone metabolism. Additionally, icariin has been shown to enhance the expression of bone-related genes and increase bone mineral density in ovariectomized rats, a common model for postmenopausal osteoporosis.

However, while the preclinical data are promising, robust human clinical trials are lacking. Most evidence comes from cell culture studies and animal research; thus, the translation to human health benefits is not fully established. There is some traditional use of Epimedium in Chinese medicine for bone health, but the modern scientific rationale is based on these experimental findings rather than direct clinical validation. Therefore, the evidence supporting icariin for skeletal system support is moderate (rated 3/5) and primarily scientific, pending further human studies.