Efficacy of Vitamin D Supplementation on Internalizing Problems Among Children and Adolescents: A Systematic Review of Randomized Controlled Trials

ABSTRACT

Internalizing problems including depression and anxiety can negatively affect the well-being of children and adolescents. Micronutrients, including vitamins, have been associated with internalizing problems and their prevention and treatment. This systematic review summarizes empirical evidence and evaluates dose–response, efficacy, and safety of vitamin D supplementation for internalizing problems among children and adolescents. A search for scientific articles was conducted in November 2021 in CINAHL, PubMed, and PsycINFO based on the PRISMA checklist. After applying inclusion and exclusion criteria, six randomized controlled trials assessing the effect of vitamin D supplementation on internalizing problems among youth (aged below 21 years) were selected for review. This review found that youth with serum 25(OH)D deficiencies may require higher doses and longer duration than the recommended level of 1,000 IU vitamin D/day for 3 months. Vitamin D supplementation was found to be safe and had a comparable effect on increasing baseline serum 25(OH)D levels. Studies that included both children and adolescents showed a more pronounced reduction in internalizing problems with vitamin D supplementation compared to studies that only included adolescents. Most studies did not report intention-to-treat analysis, which includes subjects regardless of protocol adherence. In conclusion, high dose and short duration of vitamin D supplementation intake appear to be safe and effective in reducing internalizing symptoms. It is important to encourage sufficient vitamin D intake, particularly for individuals with limited sun exposure or access to vitamin D-rich foods. Future studies should include clinical evaluation, consider populations with autoimmune diseases, and carefully control confounders.

Acknowledgments

The authors acknowledge Richard James, a librarian at the University of Pennsylvania, for helping develop the search terms.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/23794925.2023.2224111.

Additional information

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.