Vitamin D and Allergy: Urticaria Shows Strongest Signal
Key Takeaways
- Across 14 eligible meta-analytic articles covering 16 associations and 66,387 participants, the only class II association was lower serum 25(OH)D in urticaria (MD −9.35, 95% CI −12.27 to −6.44); serum 25(OH)D in allergic rhinitis was graded class III, SMD −1.29 (95% CI −1.92 to −0.65).
- In established disease, and for allergic rhinitis specifically as adjuvant therapy, vitamin D supplementation was associated with reported improvement in allergic rhinitis, atopic dermatitis, and urticaria, indicating a disease-specific pattern rather than a uniform effect across allergic diseases.
- No significant supplementation effect was reported for asthma, OR 1.04 (95% CI 0.81 to 1.34), or food allergy, OR 0.84 (95% CI 0.71 to 1.01), and prenatal vitamin D supplementation showed no significant preventive effect for offspring allergic rhinitis, atopic dermatitis, or asthma.
This umbrella review of meta-analyses evaluated serum 25(OH)D levels and vitamin D supplementation in allergic diseases, searching PubMed, Embase, Cochrane Library, and Web of Science from inception through October 21, 2025. Of 3,274 retrieved records, 1,278 duplicates were removed and 88 full-text articles were screened before 14 reviews were included; pooled effects were recalculated with random-effects models, and AMSTAR 2 appraisal and pooled evidence informed review-quality assessment. Adjuvant vitamin D supplementation was associated with lower nasal symptom scores in allergic rhinitis, SMD −2.25 (95% CI −3.05 to −1.43), lower atopic dermatitis severity, SMD −0.41 (95% CI −0.65 to −0.17), and lower urticaria clinical scores, SMD −3.63 (95% CI −5.72 to −1.54).
Across the 16 associations, 10 were statistically significant under the random-effects model and 10 showed large heterogeneity with I2 >50%. AMSTAR 2 rated 5 reviews as high quality, 3 as moderate, 4 as low, and 2 as critically low; seven overlapping associations were identified, and bias checks for small-study effects and excess significance were mixed, with detected signals in supplementation analyses for allergic rhinitis and urticaria. Lower serum 25(OH)D associations across allergic diseases remained observational and may reflect residual confounding, reverse causation, or other unmeasured factors. Prenatal vitamin D supplementation showed no significant preventive effect for offspring allergic rhinitis, atopic dermatitis, or asthma.
Clinician Questions
What was the strongest graded vitamin D association in allergic diseases in this umbrella review?
Across 16 associations from 14 meta-analytic articles involving 66,387 participants, the only class II finding was lower serum 25(OH)D in urticaria, reported as MD −9.35 with a 95% CI of −12.27 to −6.44.
Which allergic diseases showed reported improvement with vitamin D supplementation in this review?
Vitamin D supplementation was associated with reported improvement in allergic rhinitis, atopic dermatitis, and urticaria, with lower nasal symptom burden in allergic rhinitis, SMD −2.25 (95% CI −3.05 to −1.43), lower atopic dermatitis severity, SMD −0.41 (95% CI −0.65 to −0.17), and lower urticaria clinical scores, SMD −3.63 (95% CI −5.72 to −1.54), indicating a disease-specific rather than uniform pattern.
Did vitamin D supplementation show benefit for asthma or food allergy in this umbrella review?
No significant supplementation effect was reported for asthma, OR 1.04 (95% CI 0.81 to 1.34), or for food allergy, OR 0.84 (95% CI 0.71 to 1.01), in this umbrella review of vitamin D and allergic diseases.
What quality and heterogeneity pattern did the umbrella review report across vitamin D meta-analyses in allergic diseases?
The umbrella review reported that 10 of 16 associations were statistically significant, 10 of 16 had I2 greater than 50%, and AMSTAR 2 rated 5 reviews high quality, 3 moderate, 4 low, and 2 critically low; bias signals were mixed, and the observational serum-level associations were not presented as causal.