Table 1.
Single arm intervention studies of soy protein and kidney function
| Ref. | Study design | Kidney function | Subjects/group | Amount of soy protein used | Control/comparator protein | Duration of intervention | Outcomes | Notes |
| Cupisti et al[93] | Single arm dietary intervention study | Renal transplant patients with moderate HC | 13 subjects completed study (7M, 6F) | Goal was to replace 25 g/d animal protein with soy protein (dietary counseling only) | Animal protein (baseline) | 5 wk on soy diet | Significant decrease in urinary creatinine after 5 wk on soy protein compared to baseline (P < 0.05) | |
| Soy protein resulted in significant decrease in TC (P < 0.05) and LDL-C (P < 0.01) after 5 wk compared to baseline; no change in HDL-C | ||||||||
| Cupisti et al[94] | Single arm dietary intervention | Renal transplant patients and and age, sex-matched healthy controls (latter for vascular measure comparisons only) | 20 per group (12M, 8F) | Goal was to replace 25 g/d animal protein with soy protein (dietary counseling only) | Animal protein (baseline and WO) | 5 wk on soy diet followed by 5 wk WO | Renal transplant patients had significantly reduced FMD compared to age- and sex-matched control subject (P < 0.001) with no differences between groups in non-endothelium-mediated vasodilation | First study to show improvement in endothelial function in brachial arteries of renal transplant patients when animal protein substituted with soy protein |
| Soy diet did not change total dietary protein intake, BW, renal function, urinary protein excretion, serum Ca or P | ||||||||
| Soy diet reduced TC and LDL-C and LOOH (P < 0.01) compared to baseline diet | ||||||||
| Soy diet resulted in improvement in FMD (P = 0.003) compared to baseline while reactive hyperemia and endothelium-independent vasodilation was unchanged; FMD returned to baseline after WO | ||||||||
| Increase in FMD correlated to increase in L-arg/ADMA ratio (P < 0.05) with soy diet | ||||||||
| D’Amico et al[95,96] | Single arm dietary intervention | Nephrotic patients with proteinuria > 1-5 g/24 h over 25 mo and HL | 20 subjects (13M, 7F) | 0.7-0.8 g/kg per day mostly from soy protein in test diet; test diet also contained vegetable oils and no cholesterol | 0.7–0.8 g/kg per day animal protein (baseline and WO) | 8 wk baseline diet followed by 8 wk soy diet and then 8 wk WO | TC, LDL-C, HDL-C, apoAI and apoB decreased on soy diet compared to baseline diet (P < 0.001); no change in TG; lipids tended to revert to baseline during WO | Fibre, type of fat and no cholesterol were also other components of the soy protein arm that were different from the control diet; there was a modest but significant decrease in BW on the soy protein diet (no change in BMI) |
| Urinary protein, urea, Na and P excretion were reduced significantly from baseline during the soy diet (P < 0.001) | ||||||||
| Soy diet results in significant decrease in CrCl with no change in serum creatinine; this persisted during WO | ||||||||
| BP did not change |
ADMA: Asymmetric dimethyl arginine; BP: Blood pressure; BW: Body weight; BMI: Body mass index; CrCl: Creatinine clearance; FMD: Flow mediated dilation; HC: Hypercholesterolemia; HL: Hyperlipidemic; HDL-C: High density lipoprotein cholesterol; LDL-C: Low density lipoprotein cholesterol; LOOH: Lipid peroxides; WO: Washout; TC: Total cholesterol; TG: Triglycerides; M: Male; F: Famale.