From the article:

“What this study shows is that large doses of vitamin C, when ingested orally by mice, actively stimulate bone formation to protect the skeleton. It does this by inducing osteoblasts, or premature bone cells, to differentiate into mature, mineralizing specialty cells.”

[…]

The mice who received an ovariectomy – and no vitamin C – had a much lower bone mineral density (BMD) versus controls, whereas mice who received a ovariectomy and large doses of vitamin C, had roughly the same BMD as the controls, suggesting vitamin C prevented BMD loss in this group.