Effect of Zinc supplementation on child development: a systematic review and metaanalysis Protocol

Child development is one of the principal aspects of pediatrics. It is a multidimensional process, on which many factors may have different effects. Zinc is a nutritional trace element that has an essential role in neuronal activity and, consequently, in brain development. Since Zinc deficiency is prevalent in developing countries, some clinical trials were conducted to evaluate the impact of zinc supplementation on child development. Thus, we decided to run a systematic review in this area to identify the effectiveness of zinc supplements on child development. This systematic review protocol will include randomized controlled trials studies (RCTs) in which zinc supplementation was used versus placebo or no intervention, zinc supplementation with other micronutrients versus the same micronutrients without zinc. We will evaluate the effect of zinc alone and zinc co-supplementation with iron on child development. We will search the Medline, Pubmed, EMBASE, ERIC, Psychinfo, the Cochrane Central Register of Controlled Trials (CENTRAL), clinicaltrials.gov, WHO International Clinical Trials Registry Platform (ICTRP), ISRCTN Registry CINAHL, Web of Science and Scopus databases. The clinicaltrials.gov and the Cochrane Library website will also be searched for randomized trials which were registered and completed but not published yet. Two researchers will independently screen titles and abstracts of citations and read the full texts of potentially relevant studies. The data extraction and quality assessment of the papers will be done independently. Any disagreements that arise between the reviewers in the above-mentioned steps will be resolved through discussion. We will report our findings based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and use the Cochrane Collaboration's tool for assessing the risk of bias. We will aim to synthesize the results in a meta-analysis if the interventions are similar in methods. Based on the similarities and differences of primary studies, we will use the best statistical methods. This is a protocol of systematic Review and meta-analysis of the effect of zinc supplementation on child development. The strengths of this protocol after meta-analysis are as follows: We will identify the strengths and weaknesses of each study. We will also study if zinc alone and zinc co-supplementation with iron are useful for improving child development in terms of their age, their nutritional status, dose of the zinc supplementation, type of the zinc supplementation (salt), duration of the intervention and iron or other nutrient co supplementations. We will assume that the measures used for the outcome will be heterogeneous between studies. We know that each study has its own quantity. We will use the random effect models for these heterogeneous data.