Effect of Nigella sativa supplementation on kidney function, glycemic control, oxidative stress, inflammation, quality of life, and depression in diabetic hemodialysis patients: study protocol for a double-blind, randomized controlled trial

BACKGROUND AND OBJECTIVES: The kidney is probably the most crucial target of microvascular damage in diabetes, which can ultimately eventuate end-stage renal disease (ESRD). Hemodialysis is the most usual way of renal replacement therapy in ESRD. Patients receiving hemodialysis are susceptible to many complications like hyperglycemia, inflammation, depression, anxiety, and poor quality of life. So, they are constrained to consume many drugs. Medicinal herbs are used in different cultures as a reliable source of natural remedies. This study aims to determine the efficacy of Nigella sativa (NS) oil supplementation on blood glucose, kidney function tests, inflammation, oxidative stress, quality of life, and depression in hemodialysis patients. METHODS AND ANALYSIS: This double-blind, randomized controlled trial will enroll 46 patients with diabetes mellitus who give hemodialysis thrice a week. Patients who have an inflammatory or infectious disease and who are receiving nonsteroidal anti-inflammatory drugs will be excluded. Patients will be randomized to the treatment and control group, which will be recommended using two soft gels of NS and paraffin oil, respectively. Laboratory tests will be assessed at baseline and end of the study, including fasting blood sugar, glycated albumin, insulin, creatinine, blood urea nitrogen, urea, uric acid, superoxide dismutase, malondialdehyde, total antioxidant capacity, high sensitive C reactive protein, and 24-h urine volume. Also, the kidney disease and quality of life and hospital anxiety and depression scale questionnaires will be evaluated. DISCUSSION: Previous studies have reported a positive effect of Nigella sativa supplementation in chronic kidney disease, but there is no evidence that this plant is safe in hemodialysis patients. The results of this study can be helpful in better control of blood sugar and kidney function and reduce complications in diabetic hemodialysis patients. TRIAL REGISTRATION: Iranian Registry of Clinical Trials . Registered on 31 May 2020 SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13063-021-05917-y.