Effects of Calcium Lactate and Chungkukjang on Calcium Status in Rat

Effects of dietary calcium lactate (CaL-A) and Chungkukjang (Korean native fermented soybean) on bone mass, calcium status, body weight, serum glucose and cholesterol levels in young male rats were investigated. Chungkukjang was fermented by mixing 4 types of Bacillus sp., and then dried at 45$^{\circ}C$. Calcium lactate was prepared from the ash of black snail. The rats were fed a commercial rat diet for 1 week and then the experimental diets for 4 weeks. Animals were divided into four dietary groups: one calcium-deficient diet (Ca-De) and one of three with calcium supplemented diets (5 g calcium/kg diet) with either calcium phosphate (Ca-P), CaL-A, or CaL-A + Chuntkukjang (CaL-AC). Calcium supplemented diets contained 39 g Ca-P/kg diet and 28 g/kg of calcium lactate in the CaL-A and CaL-AC diets. Body weight gains during the 4 weeks in the Ca-P, CaL-A, CaL-AC and Ca-De groups were 130.45 g,112.50 g, 143.40 g and 10.20 g, respectively. Feed consumption of the groups from high to low was CaL-AC > Ca-P > CaL-A > Ca-De. The Ca-De group had low femur weights and low serum calcium concentrations, while they were comparatively high in CaL-AC, Ca-P and CaL-A groups. The Ca-De groups excreted less calcium in urine than did the other rats, probably due to increased absorption of the mineral in Ca-P, CaL-A and CaL-AC groups. Microscopic observations revealed that there were many regularly spaced holes in the femur of Ca-De group, while there were much smaller regularly spaced holes in Ca-P group. However, no holes in femur were observed in the CaL-A and CaL-AC groups. Bone surfaces were especially smooth and clean in the CaL-AC group. Serum concentrations of glucose and total cholesterol were remarkably lower in the CaL-AC group than in the other supplemented groups. These results suggest that calcium from CaL-A has higher bioavailability than from Ca-P, and dietary Chungkukjang may have a beneficial effect on calcium metabolism.