Safety and antioxidant effects of a modest soy protein intervention in hemodialysis patients

Antioxidant/anti-inflammatory effects of isoflavone-containing soy protein could partly explain why hemodialysis patients in Japan tend to outlive U.S. hemodialysis patients. However, a safety concern is that dialysis patients do not clear isoflavones well. A low-dose intervention with high isoflavone soy protein (25 g protein, four times a week for 4 weeks) was tested in 17 U.S. hemodialysis patients (eight given soy protein, nine given whey protein as a control). Soy protein intake produced no harmful effects based on a typical battery of blood safety tests. Post-treatment isoflavone levels, though high, were similar to those reported after a single 20-g soy protein intake by dialysis patients. In addition, intake of soy, but not whey, reduced plasma values for oxidized low-density lipoprotein, a risk factor for cardiovascular disease, which is a common mortality cause in hemodialysis patients. Three other measures of oxidant stress and/or inflammation were unchanged by the modest high isoflavone soy protein intervention. In conclusion, in hemodialysis patients, a fairly short, low intake level intervention with high isoflavone soy protein produced no obvious harm, and produced one potentially beneficial effect. This justifies tests of higher-dose, longer interventions with soy protein in hemodialysis patients.