Dietary soy protein benefit in experimental kidney disease is preserved after isoflavone depletion of diet

Abstract

Soy diet ameliorates renal injury in the Han:SPRD-cy rat. The relative roles of protein, isoflavones and changes in polyunsaturated fatty acid (PUFA) status are not determined. We fed male Han:SPRD-cy heterozygotes casein (C), high isoflavone soy protein (HIS), alcohol-extracted low isoflavone soy protein (LIS) or mixed soy protein diet (MIS). LIS and MIS were associated with a small decrease in animal weight compared with HIS or C. Soy diets preserved normal renal function and reduced relative renal weight (10.9-14.6 g/kg, cf. 23.6, P < 0.001), scores for cystic change (0.168-0.239, cf. 0.386, P < 0.05), fibrosis (0.013-0.015, cf. 0.032, P < 0.05), tissue oxidized LDL content (0.012-0.021, cf. 0.048, P < 0.05), inflammation (8.5-12.9, cf. 31.2, P < 0.05) and epithelial cell proliferation (6.5-13.8, cf. 26.3, P < 0.05). In post hoc testing, LIS produced a greater reduction in relative renal weight, cystic change and epithelial proliferation, whereas HIS produced a significantly greater reduction in oxidized-LDL. Soy diets were associated with increased hepatic content of 18C PUFA (P < 0.001). LIS and HIS diets were associated with a small increase in body fat content (P < 0.001). Alcohol-extracted soy protein retains its major protective effects in this model with subtle differences attributable to isoflavones.

Comparison of endpoints relevant to toxicity assessments in 3 generations of CD-1 mice fed irradiated natural and purified ingredient diets with varying soy protein and isoflavone contents

“…Testis weight differences are discussed below. Soy protein has been reported to have beneficial effects on kidney function (Ogborn et al, 1998; Ogborn et al, 2010), and soy protein has been reported to lower liver weight, as well as reduce serum and liver cholesterol and triglycerides (Ascencio et al, 2004; Nagata et al, 1981; Torre-Villalvazo et al, 2008; Wanezaki et al, 2015), although the latter effects were not observed in the present study. While there were no significant diet effects on ovary weights, there was a higher incidence of gross ovarian cysts in the three low isoflavone diets compared to the NIH-41 diet.…”

Distinctive effects of plant protein sources on renal disease progression and associated cardiac hypertrophy in experimental kidney disease

“…Hemp protein has higher arginine than casein and pea protein, but the level of arginine in soy protein is not different from the latter two sources. Soy isoflavones and other phytochemicals have also been suggested as the renoprotective agents in plant foods [46,47], but we have recently demonstrated that soy protein depleted of isoflavones by ethanol extraction also slows disease progression in this model of kidney disease [48].…”

Assessing Compositional Differences in Soy Products and Impacts on Health Claims

“…In other studies, high dietary intakes of soy isoflavones were found to be associated with lower risk of recurrence among postmenopausal patients with breast cancer positive for estrogen and progesterone receptor and those who were receiving anastrozole as endocrine therapy (Kang et al, 2010a, b) . Ogborn et al (2010) have also recently reported that a soy diet ameliorated renal injury in rats. Soy diets preserved normal renal function and reduced relative renal weight, scores for cystic change, fibrosis, tissue oxidized LDL content, inflammation and epithelial cell proliferation.…”