The effect of soy protein consumption on blood indices and renal function in type 2 diabetes with nephropathy

This study was undertaken to compare the effect of animal protein and that of soy protein on blood indices and renal function of type 2 diabetic patients with nephropathy, attending a private kidney disease clinic and Imam Hossein hospital (a university hospital) in Tehran. This cross-over randomized clinical trial was conducted on 14 patients who were free of any chronic conditions or other renal diseases. The patients were asked to follow a diet containing 0.8 gr/kg protein (70% animal and 30% vegetable protein) for 7 weeks. Then after a washout period of 4 weeks during which the prestudy diet was followed, subjects were readmitted to repeat the same cycle of consuming a similar diet with 0.8 gr/kg protein containing 35% soy protein. A 24-hour dietary recall was completed every two weeks and anthropometric indices were assessed. Hematological values and renal function were evaluated at the beginning, after 7, 11 and 18 weeks of the study. Paired t test was used for statistical analysis. There were 10 (71.5%) men and 4 (28.5%) women in this study. Mean (SD) of weight and age were 70.6(10.3) kg and 62.1(12.1) years, respectively. The differerence the effects of soy and animal protein on proteinuria was significant (P<0.001). There were no significant changes in serum and urine creatinine, blood urea nitrogen, glomerular filtration rate, serum calcium, sodium, potassium, HDL-C, LDL-C/HDL-C levels and glycemic indices between the two diets. Significant reductions were seen in urinary urea nitrogen (P<0.001), serum phosphate (P<0.006), total cholesterol (P<0.01), triglycerides (P<0.002) and LDL-C (P<0.04) after soy versus animal protein consumption. It is concluded that soy inclusion in the diet can modify the risk factors of heart disease and also reduce proteinuria and urinary urea nitrogen level.