The effects of selenium supplementation on biomarkers of inflammation and oxidative stress in patients with diabetic nephropathy: a randomised, double-blind, placebo-controlled trial

Randomized, double-blind, placebo-controlled trial in adults with diabetic nephropathy and proteinuria at Shahid Beheshti Clinic in Kashan, Iran. Participants were enrolled from March 2015 to June 2015 and were 40-85 years old; the selenium group included 15 males and 15 females.

The active regimen was 200 µg/day selenium as selenium yeast capsules for 12 weeks, compared with identical placebo capsules. Route was not explicitly stated. In the selenium group, 30 participants were randomized and 30 were analyzed in the ITT set; 26 completed the trial.

Selenium supplementation showed favorable effects on several inflammation and oxidative stress biomarkers, but the findings were mixed rather than uniformly positive. Compared with placebo, unadjusted changes favored selenium for hs-CRP (-1069.2 ng/ml vs -135.3 ng/ml, P = 0.02), MMP-2 (-612.3 ng/ml vs +76.0 ng/ml, P < 0.001), MDA (-0.1 µmol/l vs +0.4 µmol/l, P = 0.01), TAC (+174.9 vs +15.8 mmol/l, P = 0.04), and GPx (+2.3 U/ml vs -27.7 U/ml, P = 0.001). After adjustment for baseline biochemical values, age, and BMI, NO (P = 0.02) and GSH (P < 0.001) remained significant, while hs-CRP (P = 0.14) and MDA (P = 0.16) did not. The authors concluded that selenium at 200 µg/day may have therapeutic potential in diabetic nephropathy, but further research is needed.

The trial was small and short term, with only 12 weeks of follow-up and limited power for clinical outcomes. Baseline differences were present for NO, GSH, and MDA, which complicate interpretation even though adjusted analyses were performed. Findings were limited to biochemical biomarkers in a single center, and generalizability is therefore restricted.