Purpose <p>To investigate the effect of vitamin D supplementation in adults with Hashimoto’s thyroiditis (HT).</p> Methods <p>This is an integrative literature review. Articles were selected from the National Library of Medicine (PubMed) and Scientific Electronic Library Online (SciELO) databases using defined descriptors from January 2016 to August 2024.</p> Results <p>Of the articles found, 7 were included because they met the specified criteria. There were significant methodological differences between the studies, which limited the comparison. Most of the studies found that vitamin D supplementation in adult individuals with HT resulted in a reduction in thyroid-stimulating hormone (TSH) and anti-thyroperoxidase antibody (anti-TPO).</p> Conclusion <p>Although it seems to be effective in reducing hormones and antibodies related to HT, there is not enough scientific evidence to support vitamin D supplementation in patients with the disease, since studies are scarce and there is a lack of consensus on the supplementation regimen regarding dose, administration scheme and duration of treatment. Furthermore, the mechanism by which the micronutrient modulates the immune system is not fully understood. Further studies including subjects with clear diagnosis criteria and control of confounders such as diet and use of medication are recommended.</p>