Citation

Nielsen AY, Høj S, Thomsen SF, Meteran H. Vitamin D Supplementation for Treating Atopic Dermatitis in Children and Adults: A Systematic Review and Meta-Analysis. Nutrients. 2024; 16(23):4128. doi:10.3390/nu16234128 

Introduction and Purpose

Atopic dermatitis (AD) is a chronic, inflammatory skin condition affecting up to 20% of children and 10% of adults globally. Emerging literature suggests that low serum vitamin D levels may be associated with increased AD severity, raising interest in supplementation as a potential therapeutic strategy. This study by Nielsen et al. aims to synthesize current randomized controlled trial evidence on whether vitamin D supplementation reduces AD severity in both children and adults through a systematic review and meta-analysis. 

Methods Overview

• Conducted using PRISMA guidelines and registered on PROSPERO (CRD42024535014). 
• Databases searched: PubMed, EMBASE, and Cochrane, within a narrow window (19–20 April 2024). 
• Included RCTs comparing vitamin D supplementation versus control in AD patients, in both children and adults, using validated tools (SCORAD or EASI) to assess severity. 
• Risk of bias was evaluated using the Cochrane tool. Analyses were conducted using R. 

Key Findings

• Number of trials and participants: 11 RCTs involving 686 participants (children and adults). 
• Effect on AD severity: Vitamin D supplementation led to a significant reduction in disease severity, with a standardized mean difference (SMD) of −0.41 (95% CI: −0.67 to −0.16; I²=58%; p<0.01). 
• Interpretation: The moderate effect size indicates a meaningful clinical impact, though heterogeneity existed across trials.
• Conclusions: Vitamin D appears to reduce AD severity in children and adults, but larger and longer-duration RCTs are needed for confirmation. 

Strengths and Limitations

Strengths:

• Rigorously conducted and preregistered systematic review with meta-analysis.
• Inclusion of both pediatric and adult populations enhances generalizability.
• Use of validated severity metrics (SCORAD, EASI).
• Assessment of bias using established Cochrane tools. 

Limitations:

• Moderate heterogeneity (I² = 58%) suggests variability in study designs or populations.
• The short search window (two days) may have missed studies.
• Clinical heterogeneity: variations in vitamin D dosing, duration, and baseline vitamin D status were not fully addressed.
• Longer-term outcomes and optimal dosing remain unclear. 

Clinical Implications

This meta-analysis provides moderate-quality evidence supporting vitamin D supplementation as a potentially effective adjunctive treatment for AD, suitable for both children and adults. As many patients prefer non-pharmacological options, vitamin D offers a generally safe and accessible approach especially for those with known vitamin D insufficiency.

However, because the optimal dosing, duration, and serum targets are not yet standardized, clinicians should individualize supplementation and consider monitoring serum vitamin D levels. Vitamin D can complement other integrative strategies (e.g., skin barrier repair, topical therapies) but should not replace conventional care when needed. 

Reflection

As a practitioner, I often support AD patients who are open to nutritional and lifestyle interventions. This meta-analysis reinforces vitamin D as an evidence-informed, low-risk option for symptom relief. My plan more likely is to:

• Begin assessing baseline serum 25(OH)D levels in AD patients.
• Consider supplementation in those with low vitamin D levels or suboptimal sun exposure.
• Monitor symptom severity using SCORAD or EASI where feasible.
• Collaborate with patients to use vitamin D alongside core treatments, lifestyle, and skin care strategies.
• Advocate for further research into standardized dosing and long-term outcomes in diverse patient populations.

Conclusion

This systematic review and meta-analysis demonstrates that vitamin D supplementation significantly reduces AD severity in children and adults. However, continued research – especially large-scale, long-term trials – is needed to refine dosing guidelines and integration into standard treatment algorithms.