Attenuating effect of a semipurified alcohol extract of soy protein on glomerular injury in spontaneous hypercholesterolemic male Imai rats.

We investigated whether soy protein's alcohol-extractable components (SPEs; mainly consisting of isoflavones) have the ability to attenuate glomerular injury in male Imai rats of a spontaneous focal segmental glomerulosclerosis model. Male Imai rats were fed a casein-based diet with and without SPEs. Group 1 (Cont) was fed a standard diet without additional SPEs, and groups 2 (SPE-1) and 3 (SPE-2) were fed a standard diet supplemented with a semipurified alcohol extract of soy protein, 0.05 and 0.10 g/100 g of diet, respectively. Body weight, urinary protein level, serum constituents, and systolic blood pressure were evaluated every 4 weeks from 12 through 28 weeks of age. At 28 weeks of age, rats were studied morphologically. Growth rates were not different among the three groups throughout the experiment. SPE-supplemented diets resulted in less proteinuria and less hyperlipidemia. The decline in renal function shown by blood urea nitrogen and creatinine clearance was less marked in the animals fed the SPE-supplemented diets. Each SPE-supplemented diet equally induced less glomerular hypertrophy and less renal histological damage compared with nonsupplemented diets. The present study showed a beneficial effect of a semipurified alcohol extract of soy protein on glomerular disease.