Vitamin DNEW2026-10

Vitamin D status and supplementation as potential modifiers of allergen immunotherapy outcomes in respiratory allergy: A structured narrative review.

Ali Selda, Iordan Denisa-Mihaela, Vlădulescu-Trandafir Andreea-Iulia, Bumbăcea Roxana Silvia — Immunologic research

Summary

This review explores whether vitamin D levels or supplements could improve the effectiveness of allergy shots (allergen immunotherapy) for respiratory allergies like hay fever and asthma. While some studies suggest a potential benefit, especially in those with low vitamin D, the evidence is not yet strong enough for routine recommendations. More consistent research is needed to confirm these findings.

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Key points

This review examined studies on how vitamin D might affect the success of allergy shots for respiratory allergies.
Some research suggests that having adequate vitamin D or taking supplements could lead to better treatment outcomes.
However, the findings are not entirely consistent across studies due to differences in how they were conducted.
More robust and standardized research is necessary to confirm these potential benefits.

What the study looked at

This study aimed to understand if a person's vitamin D levels or taking vitamin D supplements could influence how well allergen immunotherapy (AIT), commonly known as allergy shots, works for respiratory allergies. Researchers conducted a structured review of 18 existing studies. These studies investigated either the impact of vitamin D supplements given during AIT (13 studies) or the influence of a patient's natural vitamin D levels on AIT outcomes (5 studies). Participants in these original studies were individuals undergoing AIT for conditions like allergic rhinitis or asthma. The review found that many studies reported better AIT results when vitamin D was supplemented or when patients had higher natural vitamin D levels. These benefits sometimes included positive changes in immune markers. However, the overall evidence was inconsistent, with some studies showing no additional benefit. The researchers noted significant differences in how the studies were designed and conducted, making it difficult to draw firm conclusions.

Dietary takeaway

While this review suggests a potential link between adequate vitamin D and better allergy shot outcomes, it's important to remember that the evidence isn't conclusive yet. Ensuring you meet your daily vitamin D needs through foods like fatty fish (salmon, mackerel), fortified dairy products, or sun exposure is generally beneficial for overall health. However, don't rely on vitamin D supplements specifically to boost allergy treatment without further guidance from a healthcare professional, as more research is needed to confirm this specific benefit.

Abstract

Allergen immunotherapy (AIT) represents a cornerstone in managing IgE-mediated allergic diseases, such as allergic rhinitis and asthma. By administering controlled doses of allergens over time, AIT aims to readjust immune tolerance, thereby modifying allergic responses. However, clinical responses to AIT remain heterogeneous, with a subset of patients achieving only partial benefit. This heterogeneity underlines the need for novel adjunctive approaches to potentiate the immunomodulatory effects of AIT. In this context, vitamin D has gained considerable interest, given its well-established role in immune homeostasis and regulation, as well as its emerging relevance in modulating allergic disease. This structured narrative review aims to assess the potential role of vitamin D supplementation during AIT on clinical outcomes as well as the significance of endogenous vitamin D levels on AIT clinical efficacy. A total of 18 studies were reviewed, 13 evaluating the impact of vitamin D supplementation during AIT and 5 assessing the influence of endogenous vitamin D levels on AIT outcomes. Most supplementation studies reported clinical outcomes favoring the addition of vitamin D to AIT, but three found no additional benefit, and two reported a benefit only at an earlier time point, respectively in vitamin D-deficient patients. Of the five studies examining endogenous status, three reported that higher 25-hydroxyvitamin D (25(OH)D) levels were associated with better AIT outcomes. Other findings that were reported as secondary outcomes included favorable immunologic changes, such as IL-10 production, decreased allergen-specific IgE levels, and enhanced regulatory Treg-cell activity, without formal assessment of their contribution to clinical benefit. Nevertheless, findings remain inconsistent across studies due to heterogeneity in study design, supplementation regimens, and outcome measures. While the available evidence suggests that adequate vitamin D status or supplementation may be associated with better clinical responses to AIT, the current findings remain limited by heterogeneity in study design, supplementation regimens, outcome measures, and generally small sample sizes. Therefore, the evidence should be considered suggestive rather than conclusive. Although correction of vitamin D deficiency is appropriate on general clinical grounds, its specific use as an adjunct to improve AIT outcomes cannot yet be routinely recommended. Further adequately powered, standardized, placebo-controlled studies are needed to clarify its role and inform clinical recommendations.

View on PubMed →DOI: 10.1007/s12026-026-09854-3