Vitamin D and Hashimoto's thyroiditis: what the research shows
What it found
People with Hashimoto's thyroiditis tend to have lower vitamin D levels than healthy people, and vitamin D supplements reduced thyroid antibody levels in several trials.
Whether supplements improve thyroid function is still not settled.
What they found
Studies in people
Lower vitamin D in patients
Many observational studies found that people with Hashimoto's thyroiditis had lower vitamin D levels than healthy people. Recent systematic reviews and meta-analyses of these studies confirmed the difference.
Antibodies and vitamin D levels
Several studies reported that vitamin D levels were inversely correlated with anti-thyroid antibodies (TGAb and TPOAb). This means that lower vitamin D went with higher antibody levels.
Supplementation lowers antibodies
Most randomised controlled trials in adults with Hashimoto's thyroiditis and vitamin D deficiency found that thyroid autoantibody titers decreased significantly after taking cholecalciferol. A reduction was also seen in some people with normal vitamin D levels at the start.
Doses and duration varied
Trials used doses from 1000 to 4000 IU daily for 1 to 6 months, or weekly doses between 50,000 and 60,000 IU for 2 to 3 months. The wide variety makes it hard to recommend an optimal regimen.
Thyroid function unclear
A recent meta-analysis of randomised controlled trials found that most studies did not detect any significant change in TSH levels after vitamin D supplementation. Thyroid hormones also remained mostly unchanged.
Animal and lab studies
Animal studies
In female Wistar rats with experimental autoimmune thyroiditis, vitamin D supplementation significantly decreased thyroid autoantibodies and pro-inflammatory cytokines, while anti-inflammatory cytokines increased markedly.
What the authors conclude
“The confirmation of the beneficial effects of vitamin D in the prevention and treatment of autoimmune thyroid diseases requires additional randomized, double-blind, placebo-controlled trials with longer periods of follow-up.”
Also in their conclusions
- They conclude that vitamin D plays an immunomodulatory role that appears to promote immune tolerance and could contribute to inhibiting the immunopathological process in Hashimoto's thyroiditis.
- They state that data are inconclusive and call for additional randomized, double-blind, placebo-controlled trials with longer follow-up periods.
- They suggest that when diagnosing patients with Hashimoto's thyroiditis, vitamin D replacement may be suggested as an auxiliary treatment, especially in those with vitamin D insufficiency.
How it was done
The authors wanted to review whether low vitamin D plays a part in Hashimoto's thyroiditis and whether taking vitamin D could help prevent or treat it.
They searched PubMed for studies published between January 2011 and December 2023 on vitamin D, Hashimoto's thyroiditis, thyroid autoimmunity and anti-thyroid antibodies. They included observational studies, randomised controlled trials, systematic reviews and meta-analyses in adults and children.
What it can’t tell you
- Most of the evidence linking low vitamin D to Hashimoto's thyroiditis comes from observational studies, which can show a link but cannot prove that low vitamin D causes the disease.
- The randomised trials tested different doses and durations of vitamin D, so the best dose and length of treatment are not known.
- It is not clear whether vitamin D supplementation can reduce the need for levothyroxine or stop the need for it if used early in the disease.
Who paid
- Conflicts
- The authors declare no conflict of interest.
- Authors work at
- University of Navarra, Spain; Navarrabiomed (Biomedical Research Center), Spain; Navarra Hospital Complex, Spain
The paper
- Title
- Autoimmune Thyroiditis and Vitamin D
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Cite
- Durá-Travé T, Gallinas-Victoriano F (2024). Autoimmune Thyroiditis and Vitamin D. International journal of molecular sciences. doi:10.3390/ijms25063154Free full textPubMed 38542128DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error