Role of oxidants/inflammation in declining renal function in chronic kidney disease and normal aging

Oxidant stress (OS) and inflammation increase in normal aging and in chronic kidney disease (CKD), as observed in human and animal studies. In cross-sectional studies of the US population, these changes are associated with a decrease in renal function, which is exhibited by a significant proportion of the population. However, since many normal adults have intact renal function, and longitudinal studies show that some persons maintain normal renal function with age, the link between OS, inflammation, and renal decline is not clear. In aging mice, greater oxidant intake is associated with increased age-related CKD and mortality, which suggests that interventions that reduce OS and inflammation may be beneficial for older individuals. Both OS and inflammation can be readily lowered in normal subjects and patients with CKD stage 3-4 by a simple dietary modification that lowers intake and results in reduced serum and tissue levels of advanced glycation end products. Diabetic patients, including those with microalbuminuria, have a decreased ability to metabolize and excrete oxidants prior to observable changes in serum creatinine. Thus, OS and inflammation may occur in the diabetic kidney at an early time. We review the evidence that oxidants in the diet directly lead to increased serum levels of OS and inflammatory mediators in normal aging and in CKD. We also discuss a simple dietary intervention that helps reduce OS and inflammation, an important and achievable therapeutic goal for patients with CKD and aging individuals with reduced renal function.