Evaluation of the effect of soybean on bone metabolism in the rat model with ovariectomized osteoporosis

ABSTRACT

Soybean is well known to have a wide variety of beneficial biological effects. In the present work we demonstrate another new beneficial action of soybean on bone metabolism. The effects of soybean on bone metabolism and skeletal growth were studied in mature intact and ovariectomized [Ovx] female rats. Experiment I was designed to observe the effect of soybean on bone metabolism in intact rats and included two groups [1] intact control group [2] intact feeded on soybean. Experiment II was designed to investigate the effect of soybean on Ovx rats and included another two groups [3] ovariectomized rats [4] ovariectomized feeded on soybean. After eight weeks, ovariectomy perse produced a significant increase in serum free calcium, alkaline phosphatase, parathormone hormone [PTH], osteocalcin and active vitamin D [1,25[OH]2D] with significant increase in urinary excretion of calcium and deoxypridinoline. Supplementation of Ovx rats with soybean reduced the increased serum ionized calcium, alkaline phosphatase, PTH while osteocalcin and 1,25 [OH]2D still increased accompanied with significant decrease in urinary excretion of calcium and deoxypridinoline. Alkaline phosphatase and serum osteocalcin significantly increased in intact rats supplemented with soybean while the other parameters showed insignificant changes. Our findings indicate that soybean is an estrogen agonist affecting bone metabolism in Ovx rats, however, its effect in intact rats is less