The Effects of Vitamin D Supplementation on Lipid Profile and Oxidative Indices among Diabetic Nephropathy Patients with Marginal Vitamin D Status

Abstract

Objectives: Diabetes mellitus is one of the most prevalent chronic metabolic disorders worldwide, and diabetic nephropathy is one of the major microvascular complications of type 2 diabetes. Since vitamin D is thought to play a protective role in diabetic nephropathy, this randomized clinical trial was conducted to investigate the effects of vitamin D supplementation on serum lipid profiles and oxidative/anti-oxidative indices in diabetic patients with nephropathy and marginal vitamin D deficiency. Methods: For this double-blinded, randomized, placebo-controlled clinical trial, 50 diabetic patients with GFR ˃ 60 ml/min, albuminuria ˃ 30 mg/day and serum vitamin D level between 17-22 ng/ml were randomly assigned to either intervention group or placebo group. Vitamin D group received cholecalciferol VitD3 supplement (50000 IU once a week, n=25), and placebo group (n = 25) received a placebo (miglyol oil), for 8 weeks. Serum lipid profiles [low density lipoprotein (LDL), high density lipoprotein (HDL), triglyceride (TG) and total cholesterol] and oxidative/anti-oxidative indices [total antioxidant capacity (TAC), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and malondialdehyde (MDA)] were measured before and after intervention. Results: All patients completed the study. Vitamin D supplementation significantly increased serum levels of 25(OH) D in the vitamin D group, compared to the placebo group (37.63 ± 7/73 ng/ml vs. 24.11 ± 7.6 ng/ml, P=0.001). The reductions in the serum levels of TG, LDL, and total cholesterol were significant (P=0.04, P=0.006 and P=0.02, respectively) in the intervention group, compared to the control group. After adjusting for baseline values, there was a significant increase in vitamin D levels (P=0.001) and a significant decrease in TG (P=0.007), LDL (P=0.005) and total cholesterol (P=0.001) levels in the intervention group, compared to control group. The increases in TAC, SOD, GPX, CAT, and HDL were not significant in the intervention group (P ˃ 0.05). There was no significant change in MDA levels after vitamin D supplementation. Conclusion: Vitamin D supplementation for 8 weeks among patients with diabetic nephropathy has beneficial effects on serum vitamin D status and dyslipidemia. In this group, oxidative/anti-oxidative markers are not influenced by vitamin D supplementation.