You might benefit for a DEXA scan to assess bone mass. Then you might know what you are dealing with and were to work from. There are 3 types of bone loss - osteoporosis, osteopenia and osteomalacia. The last is the only type really which can be partially reversed but the others are stages of loss. There is only one way down the slope and limiting the loss is the only preventative measure. Apart from Vitamin D and good forms of calcium, omega 3 has a lot of supporting evidence to suggest it slows the loss. Minimum 1000mg of EPA a day. I am sure you already know about weight bearing exercises and foods that accelerate the loss, right?