70 Assessing the Evidence of Micronutrients on Depression among Children and Adolescents: An Evidence Gap Map
Authors: Campisi Susan , Zasowski Clare , Shah Shailja , Shah Ashka , Bradley-Ridout Glyneva , Korczak Daphne , Szatmari Peter 
Published: August 2020

Abstract

Background
Globally, depression is one of the leading causes of illness and disability among adolescents. There is some evidence indicating that nutrition may have the ability to prevent, treat and/or influence the severity of depression. Nutritional interventions may broaden the efficacy of treatment options since they are lower in cost, easily accessible and associated with fewer side effects. This may be of particular importance in many low and middle-income countries where micronutrient deficiencies are common and supplementation may be a cost-effective public health intervention. Before determining the role nutrition interventions play in psychiatry, current research needs a unified direction for the development of effective clinical and population treatments. To be resourceful in this task, evidence gap maps (EGM), which employ a systematic approach to mapping and reporting the current evidence, are of particular usefulness.

Objectives
The aim of this EGM is to offer insight into the potential role of micronutrients in depression treatment and prevention, highlight important gaps in the literature where knowledge is scarce or non-existent, and assist in prioritizing future primary research. It also provides a structured and accessible guide for users to identify the possible efficacy of specific nutrients on depression among those 6-19 years of age.

Design/Methods
We conducted a comprehensive database search of all primary and secondary literature assessing the impact of micronutrients on depression-related outcomes such as unipolar depression, major depressive disorders, dysthymia, acute depression, and mood disorders among those 6-19 years of age. Studies from any setting that assessed the impact of interventions or deficiencies of micronutrients — vitamins and minerals — on depression were included in the EGM. Based upon current literature, the most potentially impactful micronutrients on depression included Vitamins B, C, A, D and E, as well as minerals such as calcium, copper, chromium, iron, magnesium, manganese, phosphate, potassium, selenium, and zinc. Abstracts and full-text articles were dual-screened on the basis of predefined eligibility criteria. Key characteristics of the included publications were extracted. All extracted data was visualized in an evidence matrix.

Results
Our searches identified 7,479 unique citations. After the full-text screening, 30 publications were included in this EGM representing a total of 17,906 participants (58.8% female). Some studies included more than one age range with more reports being among those greater than 10 years of age. About 45% of included studies focused on early adolescents (10-14 years), 35% on late adolescents (15-19 years) and about 20% on children aged 6-9 years. Among studies including adolescents, most studies [n= 22 (73%)] were conducted among boys and girls, seven studies (23.3%) focused exclusively on girls and only one (3%) study targeted only boys. Over half of the evidence was cross-sectional, while the other half was composed of cohort studies, randomized controlled trials and case-control/series studies. Vitamin D (n=8), zinc (n=7), iron (n= 5), folate (n=5), Vitamin A (n=2), and Vitamin B (B1, B12) (n=4) were the most studied micronutrients. There were two studies on magnesium while one study each on Vitamin C, Vitamin E, and copper (some studies examined multiple micronutrients). We did not identify research conducted on any other micronutrients suspected to impact depression.

Conclusion
To our knowledge, this EGM is the first review to map current evidence regarding micronutrients and depression in this age demographic. Currently, there is insufficient evidence to support recommendations for micronutrient supplementation in the management of depression among those 6-19 years of age. More longitudinal studies and trials are needed to confirm a role for micronutrients in the etiology and treatment of depression among children and adolescents.