Vitamin D May Reduce Risk of Hypothyroidism in Hashimoto’s

vitamin D, hypothyroidism, Hashimoto's, thyroid, vitamin D deficiency

In Hashimoto’s thyroiditis, antibodies attack the thyroid gland, and over time, many people become hypothyroid. Preventing that destruction of the gland, and as a result, preventing progression to hypothyroidism, has been a focus of research.

A number of studies have evaluated the relationship between vitamin D levels and Hashimoto’s thyroiditis, and research has shown that people with Hashimoto's thyroiditis are more likely to have low vitamin D levels.

Now, a 2017 study published in the International Journal of Vitamin and Nutrition Research evaluated the effects of vitamin D therapy on the course and progression of Hashimoto’s thyroiditis. The goal was to evaluate changes in the antibody levels after vitamin D therapy.

About Vitamin D

Vitamin D is an essential vitamin that also operates as a hormone in your body. You make vitamin D when your skin is exposed to the sun. You can also get vitamin D from foods and supplements.

Experts don’t fully understand how vitamin D works in your body, but they do know that it has a number of important functions:

  • Helps you build and maintain strong bones and teeth
  • Helps your immune system function better, and remain in balance
  • Helps with the function of your muscles
  • Helps with the regulation of insulin levels and aids in managing diabetes
  • Helps with heart health and circulation
  • Helps your respiratory system
  • Helps with brain development

    A vitamin D deficiency is defined as having 25-hydroxy vitamin D levels of less than 20 ng/mL. Vitamin D deficiency has been linked to the increased risk of a variety of health conditions, including asthma, cancer, asthma, type 2 diabetes, high blood pressure/hypertension, depression, Alzheimer’s disease, and a number of autoimmune diseases, including autoimmune Hashimoto’s thyroiditis and Graves’ disease.

    According to researchers, vitamin D deficiency is soaring in the United States, with as many as 70 percent of teenagers and adults in the U.S. considered vitamin D deficient. Part of the epidemic of vitamin D deficiency is due to increased use of sunscreen, which blocks the body’s own ability to manufacture vitamin D. A sunscreen with a sun protection factor (SPF) of 15, for example, can reduce your vitamin D production by as much as 99 percent. There are also few food sources of vitamin D in the American diet. The vitamin is primarily found in fatty fish such as salmon, tuna, and mackerel, and in products that are fortified with vitamin D, such as milk.

    Vitamin D and Hashimoto’s Thyroiditis

    The research studied a group of subjects; half of whom had elevated thyroid peroxidase (TPO) antibodies, which are evidence of Hashimoto’s disease, and the other half had normal thyroid antibody levels. All of the study group members were given 50.000 units of vitamin D weekly for 8 weeks. Their thyroid antibodies were studied again 2 months after the conclusion of their vitamin D therapy.

    The researchers made a number of interesting findings:

    • Compared to the control group who did not have Hashimoto’s, the study group members who had Hashimoto's thyroiditis had significantly lower vitamin D levels at the start of the study.
    • In those patients who had Hashimoto’s disease, their thyroid antibody levels were significantly reduced after their 8 weeks of vitamin D therapy.
    • In those patients who had Hashimoto’s disease, their HDL (high-density lipoprotein cholesterol, the “good cholesterol”) levels were significantly improved after their 8 weeks of vitamin D therapy.

    The researchers concluded that treating Hashimoto’s patients with Vitamin D may slow down the process of developing hypothyroidism, and also reduce the risks of heart disease in these patients. They recommended measurement of vitamin D levels in Hashimoto’s patients, and vitamin D therapy to correct any deficiencies.

    A Word From Verywell

    If you have Hashimoto’s, should you take vitamin D? An important first step is to have your doctor run a blood test, to evaluate your levels of 25-hydroxy vitamin D. If the level is below 20, you should definitely discuss supplemental vitamin D therapy with your doctor.

    The Institute of Medicine recommends a recommended dietary allowance (RDA) of 500 international units (IU) of vitamin D for everyone up to age 70, and 800 IU for those over 70. But is supplementing with the RDA of vitamin D enough for good health? The answer is controversial. Many integrative practitioners and naturopaths recommend that the lower cutoff for healthy vitamin D is 50 ng/mL, and that levels above 50 are necessary for the immune system and thyroid benefits of vitamin D. Talk to your doctor or practitioner about the best level of vitamin D to target for your optimal health.


    Holick MF. Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease. Am J Clin Nutr. 2004 80(suppl):1678S- 88S.

    Hu S, Rayman MP. “Multiple Nutritional Factors and the Risk of Hashimoto's Thyroiditis.” Thyroid. 2017 May;27(5):597-610. doi: 10.1089/thy.2016.0635. Epub 2017 Apr 6.

    Ke W, et al. “25-Hydroxyvitamin D serum level in Hashimoto's thyroiditis, but not Graves' disease is relatively deficient.” Endocr J. 2017 Jun 29;64(6):581-587. doi: 10.1507/endocrj.EJ16-0547. Epub 2017 Apr 11.

    Ucan B, et al. “Vitamin D Treatment in Patients with Hashimoto's Thyroiditis may Decrease the Development of Hypothyroidism.” Int J Vitam Nutr Res. 2017 Jul 12:1-9. doi: 10.1024/0300-9831/a000269.

    The Vitamin D Council. “What is Vitamin D.”