Effects of taurine supplementation on bone mineral density in ovariectomized rats fed calcium deficient diet.
Taurine supplementation has been shown to have a beneficial effect on femur bone mineral content in ovariectomized rats. It therefore seemed desirable to find out whether the beneficial effect of taurine on ovariectomized rats fed calcium deficient diet could also be reproduced. Forty female Sprague-Dawley rats were divided into two groups. One group was OVX and the other group received sham operation (SHAM), and received either control diet or a taurine supplemented diet for 6 weeks. All rats were fed on calcium deficient diet (AIN-93: 50% level of calcium) and deionized water. Bone mineral density (BMD) and bone mineral content (BMC) were measured in spine and femur. The serum and urine concentrations of calcium and phosphorus were determined. Bone formation was measured by serum osteocalcin and alkaline phosphatase (ALP) concentrations. Bone resorption rate was measured by deoxypyridinoline (DPD) crosslinks immunoassay and corrected for creatinine. Urinary calcium and phosphorus excretion, osteocalcin in blood and cross link value were not significantly different among the groups. Within the OVX group, the taurine supplemented group had not higher femur bone mineral content than the control group. This study established the need for a study on the taurine effect on bone with different calcium levels.
This experiment was originally designed to test the ability of a taurine supplement to minimize bone loss during postmenopausal model with low calcium intake. Sulfur is predominantly responsible for determining the net endogenous acid production from protein because it is the acid precursor that is oxidized to sulfuric acid (Frassetto et al., 1998). It would therefore make sense that a dietary supplement with excess sulfur-containing amino acids (taurine) could yield increased sulfuric acid production in the body. However, these data suggest that bone mineral density per weight was increased, without changes in bone resorption and bone formation, in the taurine supplemented group, and therefore have the potential to increase bone mineral density if either the study is extended or more taurine is supplemented. The beneficial effect of taurine on ovariectomized rats fed calcium deficient diet was not reproduced. Because in this study, the control and taurine groups consumed identical diets as in the previous study (besides the calcium content), and we do not know whether intestinal calcium absorption will be increased by more taurine supplement. These results indicate that no significant differences in spine and femur BMD were found due to 2% taurine diet in OVX rats fed calcium deficient diet for 6 weeks. No positive effects of taurine on bone mineral density were found in the present study. Our failure to see an association between taurine supplementation and bone mineral density may have been related to the fact that we used calcium deficient diet and the same amount of taurine. Further investigations of the relation between taurine and calcium intake level for bone mineral density are warranted.