Soy Protein Intake, Cardiorenal Indices, and C-Reactive Protein in Type 2 Diabetes With Nephropathy

OBJECTIVE—Several short-term trials on the effect of soy consumption on cardiovascular risks are available, but little evidence exists regarding the impact of long-term soy protein consumption among type 2 diabetic patients with nephropathy. To determine the effects of long-term soy consumption on cardiovascular risks, we measured C-reactive protein (CRP) and kidney function indexes among type 2 diabetic patients with nephropathy. RESEARCH DESIGN AND METHODS—This longitudinal randomized clinical trial was conducted among 41 type 2 diabetic patients with nephropathy (18 men and 23 women). Twenty patients in the soy protein group consumed a diet containing 0.8 g protein/kg body weight (35% animal proteins, 35% textured soy protein, and 30% vegetable proteins) and 21 patients in the control group consumed a similar diet containing 70% animal proteins and 30% vegetable proteins for 4 years. RESULTS—Soy protein consumption significantly affected cardiovascular risks such as fasting plasma glucose (mean change in the soy protein versus control groups: −18 ± 3 vs. 11 ± 2 mg/dl; P = 0.03), total cholesterol (−23 ± 5 vs. 10 ± 3 mg/dl; P = 0.01), LDL cholesterol (−20 ± 5 vs. 6 ± 2 mg/dl; P = 0.01), and serum triglyceride (−24 ± 6 vs. −5 ± 2 mg/dl; P = 0.01) concentrations. Serum CRP levels were significantly decreased by soy protein intake compared with those in the control group (1.31 ± 0.6 vs. 0.33 ± 0.1 mg/l; P = 0.02). Significant improvements were also seen in proteinuria (−0.15 ± 0.03 vs. 0.02 ± 0.01 g/day; P = 0.001) and urinary creatinine (−1.5 ± 0.9 vs. 0.6 ± 0.3 mg/dl, P = 0.01) by consumption of soy protein. CONCLUSIONS—Longitudinal soy protein consumption significantly affected cardiovascular risk factors and kidney-related biomarkers among type 2 diabetic patients with nephropathy.