Effects of dietary calcium supplementation on bone metabolism, kidney mineral concentrations, and kidney function in rats fed a high-phosphorus diet

Abstract

We investigated the effects of dietary calcium (Ca) supplementation on bone metabolism, kidney mineral concentrations, and kidney function in rats fed a high-phosphorus (P) diet. Wistar strain rats were randomly divided into 4 dietary groups and fed their respective diets for 21 d: a diet containing 0.3% P and 0.5% Ca (C), a diet containing 1.5% P and 0.5% Ca (HP), a diet containing 0.3% P and 1.0% Ca (HCa), or a diet containing 1.5% P and 1.0% Ca (HPCa). Compared to the C group, the high-P diet increased serum parathyroid hormone concentration, markers of bone turnover, receptor activator of NF-kB ligand mRNA expression of the femur, kidney Ca and P concentrations, urinary N-acetylβ- d-glucosaminidase activity, and urinary β2-microglobulin excretion, and decreased bone mineral content and bone mineral density of the femur and tibia. Dietary Ca supplementation improved the parameters of bone metabolism and kidney function in rats fed the high-P diet, while there were no significant differences in kidney Ca or P concentrations between the HP and HPCa groups. These results suggest that dietary Ca supplementation prevented the bone loss and decline in kidney function induced by a high-P diet, whereas dietary Ca supplementation did not affect kidney mineral concentrations in rats fed the high-P diet.