*OsteoBalance? provides 1,200 mg of calcium per serving from calcium citrate/malate and calcium microcrystalline hydoxyapatite (MCHA). This formula also includes a comprehensive profile of important bone building nutrients. Calcium citrate/malate has excellent bioavailability and provided bone mass support for postmenopausal women with low dietary calcium intake in a two-year, double-blind placebo-controlled trial. In a separate two-year trial, calcium MCHA maintained healthy bone mineral content in volunteers. One study demonstrated that concomitant supplementation of the trace minerals zinc, copper, and manganese with calcium citrate/malate helped to promote proper bone metabolism in postmenopausal subjects. Magnesium supports healthy bone mineral density and boron plays an important role in reducing urinary calcium and magnesium excretion. Like boron, vitamin D reduces urinary calcium loss but is also a key nutrient because it enhances calcium absorption. 210 count bottle.