High level science, a systematic review with meta-analysis, recently found that selenium did not have benefit for those with thyroid autoimmunity. What does this mean?  Even in light of this evidence, a trial of selenium is justified when considering a few important details. Let’s discuss.

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Selenium and Your Thyroid – A Summary of the Evidence

Dr. Michael Ruscio: Hi, this is Dr. Ruscio, DC. And let’s discuss selenium and your thyroid health. If you have a thyroid condition or are concerned that you do have a thyroid condition, chances are you’ve likely looked into or heard about selenium.

There are some studies that show that selenium can improve both thyroid autoimmunity by lowering thyroid antibodies and by helping with thyroid hormone function or conversion by assisting in the rate at which you convert T4 hormone into T3 hormone. So there’s definitely some scientific evidence showing that selenium may benefit those with thyroid autoimmunity or hypothyroidism.

Now, what about if we look at really high level science, like a systematic review with meta-analysis? Well, one was recently published. And I’d like to read you a line from this paper, which essentially shows that this systematic review with meta-analysis did not find selenium had any benefit for TSH, quality of life, or thyroid ultrasound.

And thyroid ultrasound is one way of assessing thyroid autoimmunity, because you’ll see changes in the structure that the ultrasound will yield. So this is discouraging news. When we look at a systematic review with meta-analysis, which takes the available clinical trials and summarizes them and gives us an aggregate finding of the studies, we don’t see benefit.

So what does this mean? There are a few important thoughts here. Another meta-analysis of three trials did find some benefit. So there’s some data suggesting yes, some data suggesting no.

But I think if we look at this from a slightly different angle, there’s an important factor to add in here. And that different angle is, in the same meta-analysis, they showed benefit when looking at studies that were three months in duration. But when they included studies that were six to 12 months in duration, the benefit became nonexistent.

So what this may mean is that long-term selenium supplementation is not helpful for thyroid autoimmunity or for hypothyroidism. But short-term supplementation may be.

And this, to a degree, makes sense. What may be happening is we may be using selenium to help quell inflammation and/or to replete any subtle deficiencies in selenium that only require a few months to do, and once we get past this therapeutic window of a few months, three months, then the returns may no longer be present.

So what does all this mean in terms of how to look at selenium as it pertains to your health? Well, again, there is definitely some high level scientific evidence that suggests that selenium does not help thyroid function.

However, as you’ve probably heard me say before, we want to be evidence based, but not evidence limited—meaning that we want to use the evidence that we have but not be limited by the evidence that we have.

When we look at this evidence a little more critically, we see that there may be an optimum window for which we can make a case for using selenium, which is three months.

So, the data suggests that selenium does not have positive impact overall; however, if we look more closely, a short-term window seems to be highly justifiable.

And all this considered, since there are some clinical trials showing benefit, I think we can easily justify use of selenium if we are trying to use it in the shortest term possible (so use it for a few months) and then reassess.

Reassess how you’re feeling. Reassess what your lab work shows, namely looking at your antibodies as probably the most practical marker to assess this. And then try to wean yourself off and assess if you lose any of the gains that you had achieved.

So if we look at selenium practically, not as the savior for thyroid autoimmunity, but as one nutrient that may be helpful and most likely be helpful in a short-term application, and if we’re objective in our use and conservative in our use and aim for a shorter course of use, I think we have a pretty solid case made there. And we have the highest probability for benefit and the lowest probability for detriment.

So in recap, a systematic review with meta-analysis (highest level scientific evidence that’s available) did not find benefit for selenium supplementation. However, that may have been skewed by the fact that the study looked at long-term, and selenium may not be beneficial as a long-term supplement, but may have its most therapeutic potential in a short, 3-ish month window.

So we can make a case for using selenium short-term, and as long as we’re objective and trying to use it only in the short-term, you have the highest probability for benefit and the lowest probability of either wasting your money or suffering some sort of unintended, negative consequence.

All right. This is Dr. Ruscio, DC. Hopefully, this helps you get healthy and get back to your life. Thanks!

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What do you think? I would like to hear your thoughts or experience with this.

Dr. Ruscio, DC is your leading functional and integrative doctor specializing in gut related disorders such as SIBO, leaky gut, Celiac, IBS and in thyroid disorders such as hypothyroid and hyperthyroid. For more information on how to become a patient, please contact our office. Serving the San Francisco bay area and distance patients via phone and Skype.