How Much Selenium Should You Take For Hashimoto’s?

Taking the right amount of selenium can protect your thyroid gland and help reduce your antibodies (1). 

Taking the wrong amount can make your thyroid symptoms worse and may even increase your risk of diabetes. 

Want to make sure this doesn’t happen? 

Here’s how much you need to take: 

Patients with Hashimoto’s should aim to get a dose of selenium around 75 to 150 mcg per day from all sources (including food and supplements). 

The longer answer is much more nuanced and complex but it’s worth understanding because the risk of taking too much is real and can easily be avoided. 

So before you run out and start taking selenium, let’s make sure you understand why you need it, which form you should be taking, why you don’t want to take too much, and how to tell if you should supplement at all. 

Let’s jump in: 

Why You Need Selenium

Patients with Hashimoto’s love to take selenium for one important reason: 

It protects the thyroid gland from oxidative stress. 

And if you have a thyroid autoimmune disease, this translates into less thyroid gland inflammation and damage. 

It does this by helping your body create the master antioxidant known as glutathione. 

But that’s not all selenium does, due to its incorporation into selenoproteins (2), it also helps your body activate thyroid hormone. 

Not only do you get a boost to thyroid function when you take it, you also get to target the underlying cause of Hashimoto’s which is immune dysregulation. 

Knowing this, it should come as no surprise that several studies have shown that taking selenium may help reduce thyroid antibodies. 

But this assumes a few important points: 

1. You are taking it when you actually need it
2. And you aren’t taking more than you need

Which is why I have to say a few things about dosing. 

Figuring Out The Ideal Dose Of Selenium

Thyroid experts have been all over the map when it comes to selenium dosing recommendations. 

If you go back in time just a few years, they would often recommend doses as high as 400 to 500 mcg per day for those with Hashimoto’s. 

Compared to the RDA, which is set at 55 mcg per day for men and women (3), 400 mcg per day is close to 8x higher. 

This was done based on a few studies which suggested that these higher doses are safe. 

And given the fact that some studies indicate that selenium supplementation may reduce thyroid antibodies, it seemed like a solid recommendation. 

But these recommendations failed to take into account the risk that excess selenium supplements impart on diabetes. 

Multiple studies over the last few years, including a meta-analysis of over 47,000 people (4), show that as selenium levels increase in the blood, so does the risk of diabetes and insulin resistance. 

This effect is seen with doses of selenium as low as 125 mcg, all the way up to 200 mcg per day (5) which is only half of what thyroid experts often recommend. 

If this is true, and there’s no reason to think otherwise, then it promotes a big problem for thyroid patients. 

You are already at a higher risk compared to someone without a thyroid for developing diabetes just because you have a thyroid problem. 

In fact, that risk is 2-4x higher compared to the general population (6). 

In a real way, thyroid patients may be over-supplementing with selenium in an attempt to improve their thyroid gland while inadvertently harming their pancreas. 

In other words, they may be trading thyroid gland health for pancreatic damage. 

It’s for these reasons that I think taking doses of selenium in the 75 mcg to 150 mcg per day makes the most sense. 

You can get all of the pro-thyroid benefits at lower doses without needlessly increasing your risk of diabetes when you exceed this level. 

How To Tell If You Are Taking Too Much

Why is it such a big deal if you take too much? 

Unlike other micronutrients, selenium toxicity is a very real thing. 

You can take a metric truckload of vitamin B12 and not experience any issues. 

In fact, my Thyroid B Complex contains 125,000% of the RDA for B12, but these high levels are actually beneficial and work much better than lower doses. 

If you were to even take 10-15x the RDA of selenium, on the other hand, you may start to experience selenosis (7). 

And for thyroid patients, these symptoms are a problem because they often mimic the same symptoms associated with hypothyroidism. 

Here’s what I mean: 

Taking too much selenium may cause symptoms such as: 

• Hair loss
• Brittle nails
• Fatigue
• Gastrointestinal upset
• Joint pain
• And nausea

With the exception of the GI-related side effects, symptoms like hair loss, brittle nails, and fatigue are very common symptoms in both hypothyroidism and Hashimoto’s. 

There may be a scenario in which some patients taking doses as high as 600 mcg per day of selenium may cause the very symptoms they are trying to treat. 

When combined with the risk of diabetes from taking too much, smaller doses get even more attractive. 

It’s often difficult to pinpoint if you are taking too much, but if you believe you are then the best course of action is to simply stop taking selenium. 

Your body will metabolize out any excess through your kidneys within just a few days (provided your kidneys are functioning normally). 

Food vs Supplements: How Should You Get Selenium Into Your Body?

How should you get selenium into your body? 

This one is easy: 

Food sources reign supreme. 

Food contains organic sources of selenium as selenomethionine and selenocysteine. 

Selenomethionine is the form you’ll get from eating vegetables and selenocysteine is the form you’ll get from eating animals.

Inorganic forms exist as well and these are often the forms found in over-the-counter supplements.

The inorganic forms come as selenite and selenate, but these should be avoided due to their poor bioavailability compared to the organic and natural forms.

It’s definitely possible to get organic forms of selenium like selenomethionine in supplements, but you should still aim to get as much from your diet as possible.

Why? 

Because it will force you to eat more whole foods which will support your thyroid and overall health. 

Your diet is one of the best and most powerful tools you have at your disposal for improving thyroid function and it would be silly to not use it.

Selenium can be found in high amounts in foods like tuna, shrimp, beef, pork, and turkey (8). 

Do your best to get as much selenium as you can from food and, if necessary, supplement with organic forms of selenium to make up the difference.

You can see an example of a thyroid support supplement that has the right form and amount of selenium here.

And if you are taking a selenium supplement right now, make sure you go check the back of the bottle to see what form you are taking. 

If it’s not selenomethionine or selenocysteine, get rid of it. 

By the way, selenium isn’t the only supplement that you can take to lower your thyroid antibodies and if you want to see a list of the others, check out this article next.