Antioxidant Supplementation and Diabetic Kidney Disease

Diabetes' propensity to cause metabolic derangement is directly responsible for a looming epidemic of diabetic kidney disease (DKD). And left unchecked, DKD can progress to end-stage kidney disease (ESKD).

About 50% of all those with ESKD developed it after a diabetes diagnoses. ESKD's progression is associated with an increased risk of cardiovascular events and hospitalizations, and those complications escalate in patients who need chronic renal replacement therapy by dialysis or kidney transplant.

A team of researchers from Italy has published a review and meta-analysis in the journal PLOS ONE that examines use of chronic antioxidant supplementation as a tool to retard kidney disease progression in patients who have diabetes.

The authors looked at many studies that used various antioxidants in an attempt to slow DKD. They found multiple randomized controlled trials but had difficulty comparing and contrasting the results due to varying sample sizes, study designs, and outcome measures.

One area in which there was considerable diversity was the definition of kidney disease progression to end stage. Some studies defined this point as a need for chronic dialysis or kidney transplant, but other studies used surrogate endpoints such as changes in urinary albumin excretion or renal function.

Overall, the researchers concluded that studies have shown that the use of antioxidants can reduce albuminuria. This finding is encouraging because pathological urinary albumin excretion is an early sign of DKD. In this meta-analysis, the researchers found that antioxidant supplementation was associated with significant reductions in albumin excretion.

Studies employed many antioxidants including vitamin C, vitamin E, zinc, and silymarin. Several studies used oxidants in combination. Evidence was strongest for vitamin E in doses ranging from 480 mg to 1200 mg daily.

Most studies indicated that participants reported no significant adverse events, though a few studies did not seem to examine adverse events systematically.

The authors reported that additional studies are needed to determine which oxidants and at what dose) are most likely to slow DKD progression. They also indicated the need for better definitions of outcomes.

Reference

Bolignano D, Cernaro V, Gembillo G, et al. Antioxidant agents for delaying diabetic kidney disease progression: A systematic review and meta-analysis. PLoS One. 2017;12(6):e0178699. doi: 10.1371/journal.pone.0178699.