Calcium and Phosphorus Balance Study by Soy Isoflavone Intake in Ovariectomized Rats

This study was performed to determine the effect of three different concentrations of soy-isoflavones on calcium and phosphorus balance in either sham-operated or ovariectomized female rats. Seventy-two 16-week old Sprague-Dawley rats underwent sham operation or bilateral ovariectomy. They were provided diets containing different levels of soy isoflavones for 6 weeks: 50 ppm (low isoflavone intake; LI), 250 ppm (medium isoflavone intake; MI) and 500 ppm (high isoflavone intake; HI). The subsequent fecal and urinary excretions of calcium and phosphorus were then measured. In the sham-operated rats, body weight gains and food efficiency ratio of the MI and HI groups were significantly lower than the control group while food intake was not different. However, there was no significant difference in the ovariectomized rats. The fecal excretion of calcium was significantly lower in the LI, MI and HI groups than the control group in sham operated rats, and significantly lower in the HI group than the control group in ovariectomized rats. Also, apparent absorption rate of calcium and phosphorus did not show any significant difference among groups. Urinary excretion of calcium and phosphorus was significantly lower in the HI group than the LI group in the sham-operated rats. Urinary excretion of calcium was significantly higher in the control ovariectomized rats than in the control sham-operated rats. Retention of calcium and phosphorus did not show any significant difference in both groups. From the above result, we see that isoflavone intake increases calcium retention through an increase in calcium absorption and also suppresses the increase of calcium excretion in urine in ovariectomy. Therefore, it is suggested that isoflavone intake is recommended for menopausal women who experience sharp bone loss due to the decrease in estrogen hormone.

Effect of Dietary Supplementation of Sypjeondaebotang or Jahyulyanggeuntang on Iron Bioavailability in Rats

The effect of dietary supplementation of the two oriental medicinal prescriptions, Sypjeondaebotang or Jahyulyanggeuntang, on iron bioavailability was evaluated in rats which were depleted of iron by being fed an irondeficient diet for 4 weeks. Seventy two iron-depleted rats were randomly divided into 3 groups (n = 24) , and fld one of the following experimental diets for 4 (n=8), 12 (n=8), and 25 days (n=8) : Control diet (CD), Sypjeondaebotang-supplemented diet (SD), Jahyulyanggeuntang -supplemented diet (JD). The CD contained 20 mg Fe/kg diet as FeSO4, and the SD or JD was identical except that the respective oriental medicinal prescription extract was included at the level of 4 g/kg diet. Animals fed the SD and JD for 25 days consumed significantly less food (p0.05) were lower in rats fed the SD compared to those fed the CD. Dietary supplementation of Sypjeondaebotang during the period of iron repletion significantly increased blood levels of hemoglobin (p<0.05) and hematocrit (p<0.01) measured at day 12, and increased mean corpuscular volume (p<0.05) measured at day 25, compared to the values for the CD rats. Regression analyses of hemoglobin-repletion bioassay data from rats fed the SD and JD showed the relative biological values of 123% and 99%, respectively, calculated against the slope for the CD rats. Apparent iron absorption and retention values were also significantly lower (p<0.05) in rats fed the SD for 25 days than those for the CD rats. Based on the results from diverse biochemical indices of iron status and the chemical balance study, the effect of Jahyulyanggeuntang on iron bioavailability appears to be less prominent than that for Sypjeondaebotang. Taken together, these results indicate that Sypjeondaebotang has a positive effect in restoring iron depletion by increasing the iron bioavailability in rats.