[Effect of soybean protein and high calcium intake on the concentration of serum lipids in hypercholesterolemic rats].

OBJECTIVE: To investigate the effects of dietary soybean protein or/and high calcium intake on the concentration of serum total cholesterol (TC) and serum lipids in hypercholesterolemic rats. METHODS: Following 14 days of inducing the hypercholesterolemia model successfully, 24 female rats were fed 4 experimental diets contained 20% of protein each from either casein or soybean protein and either a normal or high concentration of calcium (0.59% and 1.12%) in a 2 x 2 factorial design. RESULTS: After the experimental diets had been fed for 21 days, TC was (10.56 +/- 2.74, 7.99 +/- 2.19, 5.48 +/- 0.51 and 6.81 +/- 0.98) mmol/L in the rats fed diets containing casein and normal concentration of calcium, casein and high concentration of calcium, soybean, protein and normal concentration of calcium, and soybean protein and high concentration of calcium, respectively. According, Serum apolipoprotein B100(ApoB100) was (0.46 +/- 0.14, 0.31 +/- 0.12, 0.17 +/- 0.07, and 0.21 +/- 0.05) g/L, respectively. Comparing with the rats in casein group, the TC and ApoB100 of the rats in other 3 groups were significantly low (P < 0.05). Whereas, the changes of TG and HDL-C were not significant in these rats. CONCLUSIONS: Dietary soybean protein or/and high calcium intake lower TC in hypercholesterolemic rats and there is an interactive effect of these two dietary factors on lowering TC. Further researches are needed for explaining the possible mechanism of soybean protein and high calcium intake on lowering TC.