Abstract
Coral sand (CS) contains the highest level of soluble silicon (Si), an essential element for bone formation, among several raw materials with calcium tested. The effects of CS on bone metabolism were studied by maintaining weanling mice on basal diets containing 0.5 and 3% CS for 3 or 6 months. In comparison with the control basal diet containing calcium carbonate, the CS diet increased the bone ash weight and collagen content at peak bone mass in 4-month-old mice, resulting in increased strength and stiffness of the femur. In 7-month-old mice showing initiation of bone loss, increased bone collagen and calcium concentrations and alkaline phosphatase activity suggested stimulation of bone metabolic turnover in favor of bone formation, as reflected in increased bone weight. Mice on the 3% CS diet with intake of 171% Ca and 117% Si compared to the control demonstrated an increase in all 4 indices of mechanical bone strength, whereas mice on the 0.5% CS diet with intake of 102% Ca and 105% Si showed increased strength, deflection, and energy absorbed. These findings suggest that coral sand has distinctive characteristics of bone metabolism differing from those of calcium salts when included in the basal diet, possibly due to its high concentration of soluble silicon.
