What relationship does selenium share with your thyroid? It’s a complex, and yet incredibly important one. So, if you have been curious, I want to provide exactly the right deep dive to meet your needs. Buckle up, because we will be covering it all!

For a quick summary, we can consider selenium the ideal sidekick for iodine when it comes to your thyroid’s health. That’s because these two are the most important things your thyroid needs, and so getting it right is so important.

The truth is that, when you are in a state of selenium deficit, the thyroid cannot juggle any changes in iodine status. At all. So, it is critical to have enough of it, because of the host of additional factors that play their own role.

On the other hand, you can also get too much selenium. In cases of supplementation, that is definitely possible. But, you need some, so it is important not to avoid selenium, but to get it in the right, sustainable amounts for your system.

What Action Steps Can I Take Right Away?

If you want to get started right this moment, it turns out that dietary selenium has some benefits that are independent of supplemental selenium. Those who have autoimmune thyroid disease, though, can benefit from having a bit of both.

Therefore, I do encourage having two to four Brazil nuts per day, so you are assured adequate dietary selenium. And, in addition to that, a small amount of selenium can be found in proper supplementation.

It’s part of the reason why you can find selenium in my Daily Reset Pack. I wanted to make sure that you got enough, but in the right amounts, to help ensure that you do not have to worry about overexposing yourself to selenium.

Selenium & Your Thyroid Function

Almost everywhere in your body, you can find selenium. But, the area that has the highest concentration of it is in your thyroid.

There are twenty-five proteins that we know of, in the body, that are dependent on selenium to thrive. And roughly half of them are all needed for thyroid hormone formation.1

These are critical for every step in that entire process. We need them for:

  • Bringing iodine into the thyroid (Read more about iodine for your thyroid here)
  • Activating iodine
  • Binding iodine onto thyroglobulin
  • Getting iodine out of the thyroid
  • Using it in the tissues
  • Getting rid of the leftovers

Sounds important, doesn’t it? These all depend on getting adequate amounts of selenium, which goes to show just how essential it is for your health.

In addition to that, though, selenium is also relevant in the formation of the antioxidant glutathione. We now know that a big part of thyroid disease comes about because there may not be enough glutathione.2

Your thyroid really needs this, because it forms iodine as a free radical. Glutathione is there to help prevent damage from the iodine formed inside the thyroid. But, due to a lack of selenium, we cannot make glutathione and this can cause more and more damage.

Key Insight: The net effect is that selenium acts as a buffer, and even if your iodine intake is a little above (or below) ideal, then selenium cuts the risk of it being harmful.3

Selenium As A “Risk Cutter”

Studies have shown that selenium plays a key role in cutting down the risk for:

  • Hashimoto’s disease
  • General hypothyroidism
  • Subclinical hypothyroidism (Here’s the truth about subclinical hypothyroidism)
  • Thyroid cancer

That is true both for the development of thyroid cancer, as well as the staging and severity of thyroid cancer.

Can You Get Too Much Selenium?

Let’s not forget, though, that selenium excess can also be harmful. By and large, apart from paradise nuts (which I have discussed in another video dedicated to Brazil nuts and selenium), that won’t happen by dietary selenium alone.

Selenium & Thyroid Proteins

In addition to all this, we also know that selenium and the way it forms glutathione, the risk of your thyroid proteins being damaged are much lower.

Some studies have even borne this out en masse. Some large datasets, based on data from approximately 3,000 people, who had adequate amounts of selenium. And, another 3,000 people who did not have adequate amounts.

From there, researchers looked at all these rates of the aforementioned thyroid diseases that I mentioned. What they saw was that health selenium status cut the odds by about 95% for some of these conditions.4

Where Can You Find Selenium?

So, how do you get more selenium into your system? The obvious way is through Brazil nuts, which are notable in just how much selenium they have. Going down the list, though, we can also find selenium in the following foods:5

Animal foods are quite dense in selenium, but Brazil nuts are truly in a class unto themselves. If you have a couple of them per day, you are completely covering your bases.

How Many People Get Low In Selenium?

The next thing we need to figure out is just how common are selenium deficiencies? Would it be normal for you to get low, and how would that reveal itself?

As far as severe deficiencies are concerned, they are not that common in the modern world. But, they do occur with those who are:

  • On restrictive diets
  • Avoiding animal proteins
  • Dealing with inflammatory bowel syndrome6
  • Cutting out grains and legumes

As a generalization, the more food categories you have in your diet, the more likely your selenium is to be in the right amounts.

We also see that, within populations known to have thyroid disease, those populations tend to be lower in selenium than in populations overall.7

Do Supplements Really Help?

If you are worried about becoming deficient in selenium, the next thing you may be considering is supplementing with it. Is this the right idea?

We’ll think of this in two unique ways:

  • Cutting the risk of getting thyroid disease
  • Managing your current thyroid disease status

There is some pretty encouraging stuff right here. What we have are at least three large, placebo-controlled double-blind studies, showing that selenium supplementation can lower the level of thyroid antibodies.

This can be over a period of around six months, and often involves a reduction of 25-55% for thyroid peroxidase. Levels can be as dramatic for antithyroglobulin, but anti-TPO can go down a pretty large amount by selenium alone.

The study referenced showed that the most effective dose is around 100-200 micrograms (mcg) per day. They also showed that selenium supplements can lower abnormal findings as found on thyroid ultrasounds.

This is absolutely great news, as those same supplements had no clear effect on thyroid hormone levels. They did not shift them up or down, for good or ill, but they did lower the autoimmune process.8

Selenium & Graves’ Disease

They have also discovered that selenium supplementation can help the thyroid heal up more quickly, and reduce the risk of developing Graves’ eye disease.9

How Do You Test For Selenium?

By now, you are probably wondering how to know whether you are low in selenium. Testing is not essential, but it can be good for those who are generally curious.

Overall, selenium is rather predictable in terms of your needs and absorption. There are some nutrients, like vitamin D or iron, which can be harder to predict how much you need and how much you are truly absorbing. Selenium is less unpredictable.

While we can check blood levels, urine levels, hair levels, and tissue levels, the levels are simply normal until they are not. This makes the unreliable predictors for selenium status, so you may not need to necessarily test for it.

So, what do you do? Well, I would recommend starting with a couple of Brazil nuts! Then, have around 100 mcg in your supplementation, and you are going to be in pretty good shape from that alone.

Key Insight: When you are using the Daily Reset Pack, you are pretty much covered when it comes to supplemental selenium. Now, all you need is a Brazil nut or two!

What If You Get Too Much Selenium?

As I mentioned before, more is not always better. In fact, it can make things quite worse. There is data saying that the higher you get beyond 400 mcg per day of selenium, you can start seeing symptoms like:

Hair loss
Joint pain
And others…10

In the past, there have been some poorly-produced supplements that had hundreds of times more selenium than necessary. Clinically, I have even seen patients taking a whole host of supplements who have inadvertently gotten way too much selenium.

Key Insight: Total amounts matter, which means that when you take too many kinds of supplements, you may end up doing far more harm than good for your health.

When it comes to your dietary sources of selenium, though, it probably will not happen. You won’t get toxic from Brazil nuts, and should not have to worry about it on that front.

What Have Review Studies Concluded?

Even the most conservative research reviewers have concluded that selenium supplements are a good thing for thyroid disease. One review showed that we can see thyroid peroxidase antibodies reduce within three months (and keep on reducing over twelve).

This can occur quite markedly, with no big drawbacks. So, because selenium involves all of the known pathways involved with the thyroid, it is so important that we get it right. Both that we know how much it can benefit us, and that it is safe to supplement with it.

So, there we have it. Selenium is important, we can get it from a large range of foods, but some people may be low in it. In general, though, there are parallel benefits to having some in the diet and some supplemented (but not too much!)

Selenium Is Just The Start!

Interested in the health of your thyroid? Now that you know a bit more about selenium, the next step is to understand the overall health of your thyroid. Try taking the Thyroid Quiz today, to unlock some important insight and next steps into securing the health of your thyroid in the long term. I hope you will give it a try.


1 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5307254/
2 – https://www.ncbi.nlm.nih.gov/pubmed/28290237
3 – https://www.ncbi.nlm.nih.gov/pubmed/19594417
4 – https://www.ncbi.nlm.nih.gov/pubmed/26305620
5 – https://ods.od.nih.gov/factsheets/Selenium-HealthProfessional/
6 – https://ods.od.nih.gov/factsheets/Selenium-HealthProfessional/#h6
7 – https://www.ncbi.nlm.nih.gov/pubmed/23448365/
8 – https://www.ncbi.nlm.nih.gov/pubmed/20039895/
9 – https://www.ncbi.nlm.nih.gov/pubmed/27099835/
10 – https://www.ncbi.nlm.nih.gov/books/NBK482260/

P.S. Whenever you are ready, here is how I can help you now:

1. Schedule a Thyroid Second Opinion with me, Dr. C, Click Here for Details
2. Download and use my Favorite Recipes Cookbook Here
3. Check out my podcast Medical Myths, Legends, and Fairytales Here

Dr. Alan Glen Christianson (Dr. C) is a Naturopathic Endocrinologist and the author of The NY Times bestselling Adrenal Reset Diet, The Metabolism Reset Diet and The Thyroid Reset Diet.

Dr. C’s gift for figuring out what really works has helped hundreds of thousands of people reverse thyroid disease, lose weight, diabetes, and regain energy. Learn more about the surprising story that started his quest.