Why Is Vitamin D So Important to Thyroid Patients?

Woman wearing sun hat
Aleksandra Jankovic/Stocksy United

You have probably heard about the importance of vitamin D and that more health experts are recommending that you get more of this important vitamin. In particular, testing for and supplementing with vitamin D have been increasingly recommended for thyroid, autoimmune, and obesity patients.

But what's the thinking and science behind these recommendations?

I had a chance to have a brief Q&A with Richard Shames, MD—a practicing physician, author of a number of popular books on thyroid disease, and a thyroid coach—on the topic of why he considers vitamin D so crucial for thyroid patients.

1. Why do you feel vitamin D is so important for people with thyroid conditions?

Richard Shames, MD: This particular vitamin is so crucial to thyroid function that its status has now been elevated by researchers to co-hormone or pro-hormone. We now know that the variability of thyroid to work or not work in your body is dependent upon the presence of vitamin D, making it not just of benefit, but absolutely essential to thyroid health.

2. Where does vitamin D fit, in terms of the other nutrients that can be useful for thyroid health, for example, selenium, copper, and zinc, and issues like avoiding too much soy, and balancing iodine intake?

Richard Shames, MD: Recently I was coaching a very careful and conscientious patient with hypothyroidism. She was taking optimal amounts of the minerals just mentioned; and in addition, was taking herbal medicines to promote her thyroid health, as well as the pro-hormone pregnenolone, to increase the availability of the adrenal hormonecortisol.

Moreover, she was also taking prescription thyroid medicine, consisting of a T4 / T3 combination, with a small amount of natural desiccated thyroid for completeness.

Even with all of this effort, she was not getting good results in terms of symptom relief. After checking her vitamin D level, I found it to be in the low-normal range, and we boosted it up to mid-to-high normal range.

Only then did she begin to fially do well.

3. Why do you think this worked?

Richard Shames, MD: Thyroid treatment isn't optimal—and may not work—if you do not have adequate vitamin D for the crucial final metabolic step, which takes place at the site where thyroid hormone actually works. This happens inside the nucleus of the cell. Vitamin D needs to be present at sufficient levels in the cell in order for the thyroid hormone to actually affect that cell. That is why vitamin D is so crucial.

4. Do we get enough vitamin D from sunshine or multivitamins, or do we need to supplement?

Richard Shames, MD: These days people are using sunblocks, and staying inside working at their computers much more frequently. Therefore, we are getting less vitamin D from the sun. In addition, multivitamins typically have about 400 IU of Vitamin D, which was the RDA standard from research done back in the 1940s and 1950s. Today, this research is being questioned, with many researchers now recommending a minimum of 1,000 to 2,000 IU daily, an amount that far exceeds what's found in most multivitamins. In the case above, for example, my patient needed 4,000 IU daily to achieve her good results.

5. How can vitamin D be tested?

Richard Shames, MD: I believe that a blood test for vitamin D is essential for anyone dealing with hypothyroidism.

The typical normal range for vitamin D levels is from around 30 to 100. Keep in mind that just being in the low end of normal range will not do an adequate job for someone with an underactive thyroid. Thyroid patients need to be "replete"—and that means a level of at least 50-60 level, or greater.

6. If you are low or low-normal, is there a particular type of vitamin D you recommend?

Richard Shames, MD: Make sure it is vitamin D3. I usually recommend that my patients take at least 2,000 IU per day for maintenance, 4,000 per day if they are at the lowest end of the low-normal range, and 6,000 per day if their tests showed vitamin D levels below normal.

I typically recommend patients supplement for two to three months, and then get retested to monitor improvement. I usually have patients who were low or borderline move to the 2,000 IU maintenance dose when blood levels have reached 50 to 60 or better.


Email interview with Richard Shames,MD, October 2015