The effects of selenium supplementation on biomarkers of inflammation and oxidative stress in patients with diabetic nephropathy: a randomised, double-blind, placebo-controlled trial (Publication with Expression of Concern. See vol. 127, pg. 155, 2022)

This study was carried out to assess the effects of Se supplementation on biomarkers of inflammation and oxidative stress in patients with diabetic nephropathy (DN). This randomised, double-blind, placebo-controlled clinical trial was conducted among sixty patients with DN. Patients were randomly divided into two groups to take either 200 mu g/d Se supplements as Se yeast (n 30) or placebo (n 30) for 12 weeks. In unadjusted analyses, compared with the placebo, Se supplementation led to a significant reduction in high-sensitivity C-reactive protein (hs-CRP) (-1069.2 (SD 1752.2) v. -135.3 (SD 1258.9) ng/ml, P = 0.02), matrix metalloproteinase-2 (MMP-2) (-612.3 (SD 679.6) v. + 76.0 (SD 309.1) ng/ml, P < 0.001) and plasma malondialdehyde (MDA) concentrations (-0.1 (SD 0.7) v. +0.4 (SD 0.9) mu mol/l, P = 0.01). In addition, a significant increase in plasma total antioxidant capacity (TAC) (+ 174 . 9 (SD 203 . 9) v. + 15 . 8 (SD 382 . 2) mmol/l, P = 0 . 04) was observed following supplementation with Se compared with the placebo. Subjects who received Se supplements experienced a borderline statistically significant decrease in serum protein carbonyl (PCO) levels (P = 0.06) compared with the placebo. When we adjusted the analysis for baseline values of biochemical parameters, age and BMI, serum hs-CRP (P = 0.14) and MDA levels (P = 0.16) became non-significant, whereas plasma nitric oxide (NO) (P = 0.04) and glutathione (GSH) (P < 0.001) became statistically significant, and other findings did not change. Supplementation with Se had no significant effect on NO, transforming growth factor beta (TGF-beta), advanced glycation end products (AGE), PCO and GSH compared with the placebo. Overall, our study demonstrated that Se supplementation among DN patients had favourable effects on serum MMP-2, plasma NO, TAC and GSH, but did not affect hs-CRP, TGF-beta, AGE, PCO and MDA.