Relationship between Air Pollution and Serum Vitamin D Levels: A Systematic Review and Meta-Analysis

Abstract

Background: Elevated levels of atmospheric pollutants might disrupt the metabolism of vitamin D in the skin. Studies showed inconsistent results about the impact of air pollution on the serum vitamin D level. This study aims to systematically review the influence of air pollution on vitamin D levels. Materials and Methods: The Medline database (PubMed), Web of Science, Scopus, and Google Scholar were systematically searched up to the end of July 2020. All observational, English-language, and human studies that assessed the effect of air pollution on vitamin D levels were included. Results: Among 432 studies, 26 papers were included in the systematic review and five studies in the meta-analysis. Exposure to air pollution was associated with lower vitamin D levels (pooled mean difference (MD) = -8.04, 95 confidence interval (CI): -10.34, -5.75). There was some evidence of heterogeneity between studies (I-2 = 91.39). Conclusion: The findings revealed a reverse correlation between vitamin D levels and air pollution. Air pollutants have an impact on the penetration of solar ultraviolet B (UVB) to the Earth's surface. Consequently, the occurrence of vitamin D deficiency could be linked to air pollution.