Why Is Selenium a Recommended Supplement to Take?

Currently, I take 200ug (0.2mg) of Selenium a day, after reading about its benefits online, especially for those with hypothyroidism.

The recommended dose by many sources is no more than 200mcg (0.2mg) a day. I went for my dosage of 200ug (0.2mg) a day after reading on STTM that 0.2mg is what some people who run STTM, take, and STTM themselves recommend 200-600mcg (0.2mg-0.6mg) a day. Thyroid Pharmacist Izabella Wentz also promotes 200mg a day.

However, the NHS recommend 0.06mg a day for women and 0.075mg a day for men and this source says no more than 0.055mg a day, which is more or less in line with NHS recommendations. So with STTM and Izabella Wentz recommending 0.2mg-0.6mg a day, they’re recommending at least 3-10x the dosage of what other sources say.

Let’s cover some background on selenium first.

The National Academy of Hypothyroidism states that symptoms of low selenium include:

  • Fatigue
  • Low immunity
  • Poor concentration (brain fog)
  • Fertility/reproductive issues
  • Heart problems
  • And more!

However, selenium is not naturally occurring in the body, but is a trace mineral found in food and soil. It is vital for immune response and thyroid function, including conversion of thyroid hormone T4 to T3, making it essential for good metabolic function.

Selenium is converted into one of three types of selenoprotein, detailed below:

  • Gluthiaone Peroxidases -Antioxidants.
  • Thioredoxin Reductases- Active in cell structure and growth.
  • Iodothyronine Deiodinases – Responsible for the conversion of T4 to T3.

During times of selenium deficiency, you could have symptoms of brain fog and decreased cognitive functions, as well as lack of energy and blood results that look ‘OK’, even if you feel rubbish, still. You could also have low Free T3.

A lot of hypothyroid patients have trouble converting their T4 to T3, so a lack of the protein iodothyronine Deiodinases, could be making you hypothyroid, still. A sign being that if you’re on T4-only medication, like Levothyroxine or Synthroid, and not feeling any better, especially if your thyroid blood test results look ‘OK’ or you’re low in Free T3, then you could be low or deficient in Iodothyronine Deiodinases, and so, selenium. More info here. Therefore, selenium can help thyroid hormone conversion.

Another responsibility of selenium is the protection of the thyroid from oxidative damage.

If you try to take selenium supplements, and actually feel worse, then it’s worth knowing that selenium can make an iodine deficiency worse, so you should check to see if you have an iodine deficiency. Dr Kharazzian also says that having Hashimoto’s and taking Iodine can exacerbate the problem, so don’t supplement Iodine unless you know for sure, that you need it.

Interesting, if you also try to supplement iodine and end up feeling worse, then it could indicate a selenium deficiency.

STTM states that a dose of 200mcg (0.2mg) is effective and safe;

“At this dose, selenium can effectively reduce antibodies (TPOAB and TgAb) by as much as 55-86% and 35-92% respectively. Selenium supplementation, even in those with a sufficient selenium level, is reported  to still enhance immune response and thyroid and metabolic function.”

As well as the NAH;

“Another study published in 2002 discussed selenium’s affect on TPO (thyroid peroxidase) antibodies2. The researchers reported that they gave 200mcg of sodium selenite on a daily basis to individuals suffering from Hashimoto’s disease that had high levels of TPO antibodies. After three months, the participants’ levels were redrawn and there was a decrease of the TPO antibody value by 66.4%. Only nine of participants’ levels returned to normal.”

And Izabella Wentz explains:

“While the RDA of selenium may often be found in multivitamin/mineral combinations, that will not be sufficient for TPOAb reduction. Studies have been done to test the minimal dose of selenium for TPO antibody reduction, and that dose was established to be 200 mcg daily, even a 100 mcg dose did not produce a statistically significant TPO antibody reduction. The bioavailability of minerals is very delicate and can be greatly affected by food or the presence of other substances.”

However, the NHS recommend 0.06mg a day for women and 0.075mg a day for men and this source says no more than 0.055mg a day, which is more or less in line with NHS recommendations. So with STTM recommending 0.2mg-0.6mg a day, they’re recommending at least 3-10x the dosage of what other sites say. Worth bearing in mind. 

As we don’t yet know the potential risks of long-term supplementation of Selenium, the safest option may be to meet requirements by eating selenium rich foods like: brazil nuts, cod, tuna, mushrooms and meats. Brazil nuts are usually considered the most popular option, with just 2–3 of them a day providing roughly 0.2mg of selenium. But they need to be organic, preferably, and of very good quality, to contain the selenium you require. 

If you do want to supplement, then organic forms of selenium, such as selenium yeast or selenomethionine, are said to be safer and easily absorbed.

As with most supplements, selenium can have toxic effects when used in excess. Symptoms of selenium toxicity include diarrhea, hair loss and brittle nails.

If in doubt, test your selenium levels before you start supplementing, to ensure you don’t over-do it by taking too much. But I’d suggest that the best way is by making sure you eat a lot of selenium-rich food.

Many members of my Facebook Support Group do do well on 0.2mg (200ug) a day, though, and many sources online do say that that is the highest non-toxic dose.

You can click on the hyperlinks in the above post to learn more and see references to information given, but more reading and references can also be found at:








Because I want my blog to remain as transparent as possible, it’s important that you know I have used affiliate links in this post. This means I earn a tiny amount for each product purchased through Amazon from my blog. This doesn’t change that I love these products, it just means that as well as sharing what I love, if I drive any traffic to Amazon through the hard work of my blog, the running costs of my site get supported. Thank you. 

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I run a Facebook group, called Thyroid Family: Hypothyroidism Advice & Support Group. This group is for underactive thyroid/hypothyroidism patients only, and not medical professionals or anyone else. If you have any questions on living with hypothyroidism, or want some support, help or advice, please join us. 

I also run a group for the spouses, partners and other halves of hypothyroid patients, called Hypothyroid Patients Other Halves – Support & Advice Group. This is for the other halves only and not patients. 


About Rachel Hill, The Invisible Hypothyroidism

Diagnosed with Hypothyroidism, Hashimoto’s Thyroiditis and Chronic Fatigue Syndrome (ME), as well as having Adrenal Fatigue and experience with Depression and Anxiety Disorder, Rachel Hill blogs at theinvisiblehypothyroidism.com to help others, covering all aspects of what it’s like to have these conditions. Rachel is one of the many faces of thyroid disease and she’s passionate about helping those with hypothyroidism and giving them a voice.
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One Response to Why Is Selenium a Recommended Supplement to Take?

  1. Pingback: Acid Reflux/Low Stomach Acid and Hypothyroidism. | The Invisible Hypothyroidism

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