Moderate magnesium-restricted diet affects bone formation and bone resorption in rats.

This study investigated the effects of moderate magnesium (Mg)-restricted diet on bone formation and bone resorption in rats. Weanling Wistar strain rats were randomly divided into three dietary groups of 6 rats each and fed their respective diets; a control diet containing 0.05% Mg (C), a half Mg diet containing 0.025% Mg (1/2Mg), or a one-fifth Mg diet containing 0.01% Mg (1/5Mg), for 21 days. Serum osteocalcin level was significantly reduced with decreasing dietary Mg level. Urinary excretion of C-terminal telopeptide of type 1 collagen was significantly higher in the 1/5Mg group than in the C group. Serum insulin-like growth factor-1 (IGF-1) level was significantly lower in the 1/2Mg and 1/5Mg groups than in the C group. Serum soluble receptor activator of nuclear factor-kappaB ligand (sRANKL) level was significantly higher in the 1/2Mg and 1/5Mg groups than in the C group. These results showed that a moderate Mg-restricted diet induced a decrease in bone formation and an increase in bone resorption. Furthermore, these changes of bone formation and bone resorption might be caused by serum IGF-1 and sRANKL levels, respectively.