Meta-analysis of the association between vitamin D and autoimmune thyroid disease.

Jiying Wang,Jianhua He,Shishi Lv,Chenlin Gao,Yong Xu,Haihua Zhong,Guo Chen

doi:10.3390/nu7042485

Abstract

Although emerging evidence suggests that low levels of vitamin D may contribute to the development of autoimmune disease, the relationship between vitamin D reduction and autoimmune thyroid disease (AITD), which includes Graves’ disease (GD) and Hashimoto thyroiditis (HT), is still controversial. The aim was to evaluate the association between vitamin D levels and AITD through systematic literature review. We identified all studies that assessed the association between vitamin D and AITD from PubMed, Embase, CENTRAL, and China National Knowledge Infrastructure (CNKI) databases. We included studies that compared vitamin D levels between AITD cases and controls as well as those that measured the odds of vitamin D deficiency by AITD status. We combined the standardized mean differences (SMD) or the odds ratios (OR) in a random effects model. Twenty case-control studies provided data for a quantitative meta-analysis. Compared to controls, AITD patients had lower levels of 25(OH)D (SMD: −0.99, 95% CI: −1.31, −0.66) and were more likely to be deficient in 25(OH)D (OR 2.99, 95% CI: 1.88, 4.74). Furthermore, subgroup analyses result showed that GD and HT patients also had lower 25(OH)D levels and were more likely to have a 25(OH)D deficiency, suggesting that low levels of serum 25(OH)D was related to AITD.

Highlights

Because an estimated one billion people worldwide have vitamin D deficiency or insufficiency [1], vitamin D has become an important focus of current medical research
Articles were included in this meta-analysis if (1) they described a population-based case-control study; (2) the case group consisted of autoimmune thyroid disease (AITD) patients and the control group included healthy individuals; (3) the outcome measures reported quantitative vitamin D levels and qualitative vitamin D levels; (4) the study was a high-quality study
A meta-analysis of vitamin D receptor gene polymorphisms and AITD showed a significant correlation between certain vitamin D receptor gene polymorphisms and autoimmune thyroid diseases [34], but no meta-analysis of serum vitamin D levels and AITD has been published to date

Summary

Introduction

Because an estimated one billion people worldwide have vitamin D deficiency or insufficiency [1], vitamin D has become an important focus of current medical research. The biological activities of vitamin D are mainly manifested in the regulation of calcium-phosphorus metabolism, studies in the past 30 years indicate vitamin D may play an important role in the immune system [2,3]

Methods

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Discussion

Conclusion