We conducted a double-blind, randomized clinical trial to investigate how vitamin D3 supplementation affects Hashimoto's thyroiditis (HT) in female patients. Over three months, participants received either 50,000 IU of vitamin D3 or a placebo. Our focus was on measuring changes in serum cytokine levels and gene expression in CD4+ T cells, which play a critical role in the immune response associated with autoimmune diseases like HT.
Following vitamin D3 supplementation, we observed a significant increase in serum levels of 25-hydroxyvitamin D, while serum calcium levels also rose compared to where they started. However, when checking for changes related to immune response, we noted that supplementation led to a decrease in interleukin-17 (IL-17) levels, but this change didn't differ significantly from those in the placebo group.
On the other hand, the transforming growth factor-beta (TGFβ) gene expression rose significantly with vitamin D3 treatment, yet once again, we didn't see a noticeable difference between the two groups. Importantly, there was no marked effect on other key immune markers, such as interferon-gamma and IL-4 levels. Although we did see some increase in T-bet and GATA3 transcription factors, the overall impact of vitamin D3 on Hashimoto's thyroiditis in our study suggests limited benefits.
This trial sheds light on the complex relationship between vitamin D supplementation and autoimmune conditions like Hashimoto's thyroiditis. While vitamin D3 shows some promise, further long-term studies are essential to truly understand its role and effectiveness in managing HT.