The effect of vitamin D and magnesium supplementation on clinical symptoms and serum inflammatory and oxidative stress markers in patients with COVID-19: a structured summary of a study protocol for a randomized controlled trial
Authors: Ramezani-Jolfaie Nahid , Eftekhar Ebrahim , Dadinasab Mohadese , Hesarooeyeh Zahra Ghaeini , Pakdaman Pooria , Razmpour Farkhondeh , Javedan Gholamali , Khayatian Mahmood , Azad Mehdi Hassani , Davoodian Parivash , Brahimi Elham , Rafati Shideh , Nikoofal-Sahlabadi Sara , Mohammadi Mohammad 
Published: February 2023

Abstract
Objectives
This study aims to evaluate the effect of vitamin D and magnesium supplementation on clinical symptoms and serum inflammatory and oxidative stress markers in patients with COVID-19.

Trial design
This study is a 4-arm randomized, double-blind, placebo-controlled clinical trial with a factorial design and the intervention period is 3 weeks.

Participants
This study is conducted on COVID-19 patients admitted to the Shahid Mohammadi hospital in Bandar Abbas, Iran, who are eligible for inclusion in the study. Patients are included only if they meet all of the following criteria: (1) aged from 18 to 65 years old; (2) confirmation of COVID-19 by RT-PCR test; (3) completing informed consent; (4) passing less than 48 h since the patient's hospitalization; (5) no skin or gastrointestinal allergies due to taking multivitamin supplements, vitamin D, and magnesium; and (6) having more than 30 breaths per minute and less than 93% oxygen saturation in room air and sea level. Patients are excluded if they have any of the following conditions: (1) pregnancy or lactation; (2) taking a daily multivitamin or take a vitamin D or magnesium supplement in the last month; (3) participating in other clinical trials; (4) renal failure or dialysis, severe liver disease or cirrhosis; (5) known diagnosis of hypercalcemia; (6) discharging from the hospital less than 24 h after the start of the intervention; (7) history of kidney stones in the last year; (8) transfer the patient to the ICU; (9) baseline vitamin D levels above 80 ng/ml; (10) baseline magnesium levels above 2.6 mg/dl; and (11) unwillingness of the patient to continue the study.

Intervention and comparator
Participants will be randomly allocated to one of the four following groups: (A) vitamin D (two 50,000 IU capsules at the beginning of the study, two 50,000 IU capsules on the 4th day, one 50,000 IU capsule on the 11th day, and one 50,000 IU capsule on the 17th day) and magnesium supplement (300 mg/day); (B) vitamin D capsule and magnesium placebo; (C) magnesium supplement and vitamin D placebo; and (D) vitamin D placebo and magnesium placebo.

Main outcomes
The resolution of clinical symptoms (fever, dry cough, shortness of breath, headache, myalgia, oxygen saturation, and mortality rate) and interpretation of laboratory assays (CRP, MDA, TAC, WBC, neutrophils count, lymphocytes count, ratio of neutrophils to lymphocytes, levels of 25 hydroxyvitamin D and magnesium) will be assessed in the study groups.

Randomization
A computer-generated block randomization list is used for randomization.

Blinding (masking)
Investigators and patients are blinded to group allocation and treatment. A double-blind design is achieved using matched placebos.

Numbers to be randomized (sample size)
A total of 104 eligible patients are randomized into four groups of 26 subjects (1:1:1:1 allocation ratio).

Discussion
With the rapid prevalence of COVID-19 in recent years, more attention has been paid to effective dietary supplementation to improve clinical symptoms and biochemical parameters in these patients. To our knowledge, this is the first study to evaluate the effects of vitamin D supplementation in combination with magnesium or alone with respect to this infectious disease. The findings of the current RCT will provide evidence regarding the effectiveness of dietary supplementation strategies to improve COVID-19 outcomes.

Trial status
Ethical approval of the first version of the study protocol was obtained from the medical ethics committee of Hormozgan University of Medical Sciences, Bandar Abbas, Iran on May 30, 2021 (IR.HUMS.REC.1400.085). Currently, the recruitment phase is ongoing since August 23, 2021, and is anticipated to be complete by the end of August 2022.

Trial registration
The study protocol was registered in the Iranian Registry of Clinical Trials (https://www.irct.ir; IRCT20210702051763N1) on August 14, 2021. https://www.irct.ir/trial/57413

Full protocol
The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this letter serves as a summary of the key elements of the full protocol.