Vitamin D and Thyroid Disease – Can Increasing Vitamin D Intake Improve Your Thyroid Treatment?

There is some evidence that thyroid treatment will be compromised if adequate vitamin D blood levels are not maintained. But maintaining recommended levels often requires stronger supplements than we might expect.


Several articles published over 20 years ago reported that patients with hypothyroidism had low levels of Vitamin D. But the NHANES health study of over 15,000 Americans found that vitamin D deficiency is common throughout North America and certainly not peculiar to people with thyroid problems. So is there a link between hypothyroidsm and vitamin D deficiency?


We do know that vitamin D and thyroid hormones bind to similar receptors called steroid hormone receptors. And we know that a particular gene in the vitamin D receptor will predispose people to autoimmune thyroid disease such as Graves’ disease and Hashimoto’s thyroiditis. But more research is required to determine if the same gene impacts vitamin D absorption or the transformation of vitamin D into its final state as a hormone.


In his book “Thyroid Power” Richard Shames argues that thyroid treatment may not work if a person does not have adequate blood levels of vitamin D. Similar to the recommendations of the Vitamin D Council, he recommends that thyroid patients maintain levels of 50-60ng/ml or 125-150nmol/L throughout the year. Maintaining these blood levels requires most people to take vitamin supplements. This is especially true for people subjected to a “vitamin D winter” when the ultra violate rays of the sun are too weak to produce vitamin D through our skin.

The Vitamin D Council suggests that people living north of the 32 latitude (which is north of Boston, Rome or Beijing) consider the following program to maintain optimal blood levels:

Late Fall and Winter: 5,000 IU

Early Fall and Spring: 2,000 IU

Summer: regular sunbathing may be sufficient

As many of us are vitamin D deficient, some experts recommend that we take 5,000 IU vitamin D daily for three months before taking a 25(OH)D blood test to identify the supplement level required throughout the year.

The timing of the blood test is especially important as we are at our peak vitamin D level around September in northern climates and at our lowest level in March. A blood test taken during the summer will not help us to find the correct supplement strength to maintain adequate blood levels throughout the winter if we live in a northern climate.

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