Feeling sluggish and have no energy to get through the day? Do you have pain or discomfort after eating? You could be suffering from a nutrient deficiency or food sensitivity. Want to get back on track and feel your best? 
By Heidi Moretti, MS, RD
Vitamin D: Do You Need It for You Thyroid Health?
When it comes to a topic like thyroid, context is everything.
Rates of thyroid disorders are astoundingly high and are rising every year. In that context, we know that something in our world isn’t going well.
Our genes aren’t changing that fast. However, our environment and lifestyles are. One of the biggest known factors right now is vitamin D deficiency as far as a known lifestyle risk factor for MANY diseases, including thyroid diseases.
Why is Vitamin D a Problem?
There are certainly a lot of other factors to consider with thyroid function, but what we DO know is that vitamin D deficiency is epidemic. Why?
100 years ago, we spent most of our time outside, with no regard for sunscreen.
We didn’t even HAVE sunscreen. We worked outside, did our laundry outside, and even “did our business” outside, unless you were royalty, but I digress.
Vitamin D is largely sourced from the sun, not foods. This is a very big misconception today, even in medical circles.
Vitamin D is technically a hormone, not a vitamin. As such, it has over one thousand functions in the body, from gene regulation to proliferation.
Vitamin D and the Autoimmune Connection with Thyroid Disorders
Most thyroid diseases are autoimmune in nature, such as Hashimoto’s thyroiditis and Grave’s disease.
A big cause of autoimmune disease is loss of immune tolerance.
Vitamin D deficiency is known to fuel this fire of immune intolerance. Our bodies start fighting themselves because we are missing key components for our immune systems to function properly.
Take the example regulatory T-cells. These are T-cells that help regulate the immune response and are often low in people with autoimmune disease (1).
We have many clinical research studies that demonstrate how vitamin D helps to control the “out-of-control” immune response related to autoimmune disease.
In a study of children with autoimmune thyroiditis, low vitamin D status was associated with increased T regulatory cells called FOXP3 Treg cells (2).
We also now have direct evidence that vitamin D supplementation influences cell-mediated immunity. Supplemental vitamin D3 at 4000 IU per day reduced CD 4 activation more than low-dose vitamin D in a randomized trial 38 patients with autoimmune thyroiditis (3).
Vitamin D at doses of 140,000 IU monthly compared to placebo improved the immunomodulatory response in healthy people by causing upregulation of T regulatory cells, with a net increase in percentage of immune regulation (4).
Another small clinical trial found similar results when supplementing vitamin D3 for patients with Type 1 diabetes, another autoimmune disorder (5).
We also have many other autoimmune disorder trials with similar results, which add to the mounting evidence that vitamin D status and autoimmune diseases are quite inseparable.
Symptoms of vitamin D deficiency are interestingly similar to symptoms of low thyroid (both are hormones). Low energy, weight gain, skin dryness, mood changes and more.
Practical Approaching When Deciding to Use Vitamin D
When looking at vitamin D in relation to thyroid health, I like to consider the following:
What are the benefits, risks, odds, cost, and stakes? Also known as BROCS.
These are assessments decision factors as coined by Dr. Sidney Baker, MD, a brilliant Yale graduate physician that is changing the way we treat health (6).
We may never have giant trials of vitamin D, due to political and money impedances, but we do have common sense, do we not? We also have plenty of epidemiological and mechanistic data available to support use of vitamin D3 in helping to manage thyroid disorders.
Benefits
What are the known benefits of vitamin D implementation for thyroid function? As stated above, vitamin D3 supplements reduce the fire of immune dysregulation by increasing T regulatory cells.
While we do have conflicting data on whether or not vitamin D effects thyroid antibodies (7) , the largest trial and dosing to date showed that supplemental vitamin D3 as cholecalciferol at a dose of 60,000 IU per week along with 500 mg/day of calcium reduced thyroid antibodies (8).
Another trial using lower dose vitamin D3 supplements found improvement in thyroid antibodies compared to placebo (9).
Studies that did not show benefit of vitamin D also did not specify the type of vitamin D. It is well-known that vitamin D3 is more effective at increasing serum 25 hydroxyvitamin D levels than vitamin D2, has a larger dose-response and is also safer
On a macro level, consider this:
- 9 studies have found that vitamin D blood levels predict the quality of life in diseases ranging from colitis and multiple sclerosis to fibromyalgia.
- 9 additional studies have shown that supplemental vitamin D3 improves quality of life (10)
Risks
What are known risks of vitamin D3 supplementation?
Almost zero.
A handful of case reports of vitamin D toxicity exist and were mostly when the subject took more vitamin D than intended (11).
25 hydroxvitamin D, the blood measure of vitamin D status, can reach 300 ng/ml before a person will typically exhibit toxicity.
What are known risks of supplementation?
Minimal. After decades of clinically treating patients, a couple of side effects come up, although rare. Some people appear to have Herxheimer-type reactions to vitamin D3 supplementation. In these cases, doses should start low and titrate up. Additives to various supplementation products may also inadvertently create a reaction in the body. Vegan vitamin D3 is also now available.
Odds
What are the odds vitamin D is going to work to help your patient’s thyroid?
The odds are much better for taking vitamin D3 than not taking it.
A cohesive look at vitamin D and its benefits to quality of life, immune regulation and even possibly to the antibodies for thyroid function demonstrate a high probability for improvement in thyroid health.
Costs
What is the cost?
Cheap, pennies a day. Vitamin D3 is typically sourced from lanolin, so it will always be pretty affordable.
Vitamin D testing in some clinics can cost up to $200, but online blood spot tests, which are typically very accurate, can be as low as $50. Learn where you can get your levels tested.
Stakes
The stakes are high because vitamin D3 can help many aspects of health, especially for people with severe deficiency. They have a lot to gain because vitamin D deficiency is rampant, and vitamin D has over 1000 roles for health in the body.
Important considerations
Cofactors matter, meaning a good diet, including getting plenty of magnesium, vitamin A, vitamin K2, zinc and boron.
Optimal vitamin D status is still a matter of debate, but most experts in vitamin D recommend that 25- hydroxyvitamin D levels should be at least 50 ng/ml for autoimmune disorders.
Why should vitamin D be considered for thyroid prevention and even management?
- Thyroid treatment currently isn’t ideal.
- Thyroid disorders are inordinately high.
- We know the sun can easily give you over 10,000 IU per exposure.
- No known toxicity of vitamin D has been ever seen at doses of 10,000 IU.
It is important for you to know how the RDI came about. Back when vitamin D was first discovered, in the early 1900s, it was noted that children who got 1 tsp of cod liver oil per day didn’t get rickets. Later, a lab was able to measure the amount of vitamin D in this tsp. It was 400 IU. That’s about it. That is how we have based our RDI from then until now. The IOM slightly bumped up the RDI in 2007, but not by much.
Dogmatic thinking, industry influence, and ignorance, not research, keeps the RDI low.
To Sum It all Up
In summary, for vitamin D and thyroid, the benefit potential is high, the risk is low, the odds are decent, the cost is low and the stakes are high for gains.
Give the body what it needs, and it has a strong propensity to heal.
A personal note, I had a weird thyroid issue myself called subacute thyroiditis. Although rare, it is more likely to occur in people who have had it before. I had it BEFORE I aggressively treated my vitamin D deficiency. I now maintain my vitamin D status at a dose of about 8,000 IU per day.
Speaking of stakes, mine were high. I had low energy, poor immunity, low muscle strength, poor sleep, and thyroid issues. These things went away after I tested and treated my deficiency.
My thyroid function has been pristine since. My story is n=1 folks, but if you add up all the n=1’s out there, we’ve got a story to tell.
Clinical trials are not the only way to assist people with their health. We have so much evidence to treat deficiency. We just need to be open.
Heidi Moretti, MS, RD has worked as a clinical nutritionist for 18 years and has conducted vitamin and protein research throughout her career. She is passionate about integrative and functional nutrition. She is a blogger and also has a private practice; you can find her on Twitter, Facebook, Pinterest and her website
Looking for information on how to get your levels tested? Contact me.
I'm Jeanette Kimszal, a Registered Dietitian Nutritionist. After working in the corporate world of advertising for over 7 years I realized I wanted to turn my love for nutrition into a career. 
