Effect of soy consumption on oxidative stress, blood coagulation factor activities, and blood homocysteine and phosphorus levels in peritoneal dialysis patients

Cardiovascular diseases are the most important cause of mortality in patients with chronic renal failure, including peritoneal dialysis patients. Oxidative stress and increased plasma concentrations of homocysteine and coagulation factors are the major risk factors for cardiovascular diseases in these patients. Some studies have shown beneficial effects of soy consumption on oxidative stress and hyperhomocysteinemia; however, no study has been done in this field in peritoneal dialysis patients so far. The present study was designed to investigate the effects of soy consumption on oxidative stress, blood coagulation activities, and blood homocysteine and phosphorus levels in peritoneal dialysis patients. This study was a randomized clinical trial in which 40 peritoneal dialysis patients (20 males and 20 females) were randomly assigned to either the soy or the control group. The patients in the soy group received 28 g/d textured soy flour (containing 14 g soy protein) for 12 weeks, while the patients in the control group received their usual diet without any soy. At the baseline and after 8 weeks 10 ml blood were collected from each patient after a 12 to 14-hour fast and then blood ox-LDL, homocysteine, phosphorus and fibrinogen concentrations and the activities of coagulation factors VII, IX and X were measured. The initial plasma content of coagulation factor IX activity decreased significantly by17% in the soy group at the end of the 8th week (P<0.01), and the magnitude of reduction was significantly different as compared to the control value (P<0.05). The content of coagulation factor IX activity did not change significantly in the control group. The data also showed that there were no significant differences between the mean changes in blood ox-LDL, homocysteine, phosphorus and fibrinogen concentrations and the activities of coagulation factors VII and X of the two groups. The results of the present study indicate that soy consumption reduces plasma coagulation factor IX activity significantly in peritoneal dialysis patients. Therefore, it may be effective in preventing thrombosis and cardiovascular diseases in these patients.