Soy-based renoprotection

Abstract

Chronic kidney disease (CKD) is a significant public health problem as risk factors such as advanced age, obesity, hypertension and diabetes rise in the global population. Currently there are no effective pharmacologic treatments for this disease. The role of diet is important for slowing the progression of CKD and managing symptoms in later stages of renal insufficiency. While low protein diets are generally recommended, maintaining adequate levels of intake is critical for health. There is an increasing appreciation that the source of protein may also be important. Soybean protein has been the most extensively studied plant-based protein in subjects with kidney disease and has demonstrated renal protective properties in a number of clinical studies. Soy protein consumption has been shown to slow the decline in estimated glomerular filtration rate and significantly improve proteinuria in diabetic and non-diabetic patients with nephropathy. Soy’s beneficial effects on renal function may also result from its impact on certain physiological risk factors for CKD such as dyslipidemia, hypertension and hyperglycemia. Soy intake is also associated with improvements in antioxidant status and systemic inflammation in early and late stage CKD patients. Studies conducted in animal models have helped to identify the underlying molecular mechanisms that may play a role in the positive effects of soy protein on renal parameters in polycystic kidney disease, metabolically-induced kidney dysfunction and age-associated progressive nephropathy. Despite the established relationship between soy and renoprotection, further studies are needed for a clear understanding of the role of the cellular and molecular target(s) of soy protein in maintaining renal function.

Keywords: Chronic kidney disease; Diet; Proteinuria; Protein; Soy

Core tip: This review summarizes the data, both animal and limited human studies, that support the hypothesis that a soy-enriched diet is protective against chronic kidney disease. While the clinical studies have small subject numbers, the data suggest that soy improves renal function, or attenuates the progression of chronic renal dysfunction. The potential mechanisms of action, from both experimental and clinical studies, is also discussed, including positive effects on lipid and blood glucose profiles, improved vascular function and reduced inflammation. Consideration is also given to the potential active ingredients within soy, including both protein and isoflavones, that may mediate the renoprotective effect of the botanical.