Volume 30, Issue 173, July 2026

Vitamin D as an immunomodulator in selected infectious diseases

Adam Kubisa^1♦, Mikhail Kazachok², Szymon Paruszewski², Aleksandra Dybcio³, Katarzyna Kupczyk², Mikołaj Jońca¹, Natasza Kurys⁴, Dorota Szydłowska⁵, Mateusz Miluski¹, Julia Kupczak⁶

¹Pomeranian Medical University, Szczecin, Poland
²Medical University of Warsaw, Warsaw, Poland
³Medical University of Lublin, Lublin, Poland
⁴Medical University of Lodz, Lodz, Poland
⁵Medical University of Opole, Opole, Poland
⁶Lazarski University, Warsaw, Poland

^♦Corresponding author
Adam Kubisa, Pomeranian Medical University, Szczecin, Poland

ABSTRACT

Vitamin D deficiency has become a widespread global health concern, particularly in industrialized societies, where limited sun exposure reduces endogenous synthesis. The aim of this review is to summarize current knowledge regarding the role of vitamin D in immune regulation, with particular emphasis on some of the infectious diseases. This review focuses on recent experimental and clinical studies exploring the mechanisms of vitamin D action and their clinical relevance. The active form of vitamin D enhances antimicrobial peptide production (defensins), modulates cytokine responses, and affects the differentiation and function of immune cells, including dendritic cells and T lymphocytes, through Toll-like receptors. By facilitating intracellular communication vitamin D may also help to maintain epithelial barrier integrity. Observational clinical studies suggest an association between low vitamin D levels and increased susceptibility to infections. The observational nature of these studies, however, does not provide certainty as to the validity of the theses put forward based on the observed correlations.

Keywords: vitamin D, general medicine, immunomodulation, infection

Medical Science, 2026, 30, e129ms3881

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Published: 21 July 2026