Selenium supplementation and clinical outcomes: an umbrella review protocol

Background: Selenium is a trace element essential for the normal functions of different human body systems and its deficiency has been associated with different disease states. In recent years, many systematic reviews of randomized clinical trials in humans have demonstrated various properties of selenium such as antioxidant, anti-inflammatory, increased immunity, blocking tumour invasion and metastasis in various pathological conditions. Therefore, there is need to summarize these recent findings in one single paper to facilitate the decision making of clinicians and policy makers regarding the inclusion of selenium supplementation in routine clinical practice, treatment guidelines and essential medicine list. This study would guide researchers towards future research and design of clinical trials. Objectives: The objective of this umbrella review is to assess the clinical outcomes of selenium supplementation in different disease states and to determine its therapeutic implications. Eligibility criteria: Only systematic reviews of randomized clinical trials reporting clinical outcomes after the use of selenium alone as a supplement in the management of diseases will be included. While primary studies, systematic reviews that involved the administration of selenium in combination with other trace elements for the prevention or treatment of diseases will be excluded. Methods: The following databases will be searched by three independent reviewers: MEDLINE, PUBMED, EMBASE, COCHRANE database of systematic reviews, CINAHL, JBI Evidence synthesis, EPISTEMONIKOS, SCOPUS, Web of Science and TRIP PRO. Unpublished reviews will be searched using ProQuest for dissertations and Theses, Canadian Agency for drugs and Technologies in Health (CADTH) database of Grey matters and GOOGLE scholar. Systematic reviews published in the last 10 years (2013 to 2023). There will be no language restriction. The services of a translator will be employed if studies in other languages were found. Selection of reviews and data extraction will be done by 3 independent reviewers. Summary of findings will be presented in tables accompanied by texts where necessary. Keywords: Selenium, clinical outcomes, systematic review, disease management, umbrella review Strengths and limitations of this study This is the first umbrella review on the use of selenium supplements for disease management. Secondly, the findings from this study would facilitate the decision making of clinicians and policy makers regarding the inclusion of selenium supplementation in routine clinical practice, treatment guidelines and essential medicine list. Nevertheless, a major limitation of this umbrella review would be a reduced scope of eligible studies because only systematic reviews/ or meta-analysis that included randomized clinical trials will be considered. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study did not receive any funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors