Randomized, double blind, placebo-controlled studies have reported statistically significant benefits of calcium supplementation for bone health. Magnesium, like calcium, is an essential bone matrix mineral that promotes healthy bone metabolism. A trial involving 2,038 older individuals indicated that higher intakes of magnesium were positively associated with bone mineralization for certain individuals. Vitamin D promotes intestinal calcium and phosphorous absorption and reduces urinary calcium loss, essential mechanisms for maintaining healthy calcium levels in the body and for healthy bone composition. A recent 7-year study involving 36,282 women indicated that combined supplementation of calcium and vitamin D promoted healthy hip bones. Boron supports calcium, phosphorous, magnesium and vitamin D metabolism and plays a role in reducing urinary calcium and magnesium excretion. In addition, it strengthens the connective structure in bone matrix. Silica is a component of connective tissue and studies have suggested that it supports bone and collagen formation. A cross-sectional study involving 2,847 people suggests that optimal silicon intake is positively related to bone mineral health, particularly for cortical bone. Research suggests xylitol may help facilitate intestinal absorption and retention of calcium, as well as promote healthy bone structure and strength.