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T2 Thyroid Supplement: Hope or Hype?

Breaking down the pros and cons of taking supplemental T2 thyroid hormone…

T2 thyroid supplements have become the latest craze in our industry, so I wanted to make a video giving you my two cents. If you’re taking T2 and feel awesome, great! But otherwise, I wouldn’t recommend it. Watch the video to learn about the issues with supplemental T2, including the doses used, lack of quality scientific research, and the fact that it doesn’t do anything to address the root cause of suboptimal thyroid physiology.

Video Transcript

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Today we’re talking about T2. There’s a big push right now by some in the thyroid functional medicine community to recommend T2 as a supplement, and I’m getting a lot of questions about whether people should take it. I’m also seeing clients come in who don’t feel well and are taking it. So let me give you my two cents on it…

Here’s what typically happens. Somebody gets diagnosed with hypothyroidism, maybe they get on T4 initially and feel good, but then they kind of plateau. So they tinker with their doses of T4, but they still don’t feel well and wind up going to somebody, maybe more integrative, who then looks at a more complete panel – their T4, T3, free T4, free T3, reverse T3 – and they say, “Ah, I’ve uncovered your problem. You don’t convert T4 to T3. Your T3 and your free T3 are low, so we’re going to put you on T3 supplementation.”

So you add in T3, whether that’s Armour or it’s individual T4 and T3. A lot of times initially it feels good, but then many people again hit their plateau. They get frustrated with the combination of T4 and T3. 

Some people will then go try T3 only, because some voices in our space are saying, “Hey, T3-only is maybe the way to go for some people.” 

And many of them still don’t feel and function well, even though they’ve had their T4 optimized and their T3 optimized and they’ve had their reverse T3 suppressed by higher doses of T3 and low T4 medication.

So the same voices are now recommending T2 supplementation and a lot of times they’re saying, “Hey, it’s backed by the science and the literature.” But honestly, there isn’t a lot of science and evidence that T2 is beneficial for humans in vivo studies in doses that are reasonable.

Most of the studies that are available out there are done on mice and rats and they’re at super-physiologic doses of T2. T2 is typically in very small concentrations (at least that’s what we think), and there’s discussion as to how long the half-life is. We don’t know if it actually accumulates in some tissue or gets metabolized quickly. It’s just too early to know.

So the big question for me is if you’re not doing well on T4 and then you go to T3, and then you plateau, is T2 really the solution? Is that the thing that’s going to fix or optimize your thyroid physiology? And the answer to that is probably no. 

Cells typically operate in one of two modes. One is low-stress manufacturing mode where they’re bringing T4 into the cells and converting it into T3 at a higher rate to drive metabolism. 

So if you get a thyroid panel done and you see that you don’t do a good job of converting T4 to T3, that may be the result of why you have hypothyroid signs and symptoms. 

But adding T3 to a system that’s already not converting T4 to T3 doesn’t always provide the long-term benefit that we think. So if you’re not doing a great job converting T4 to T3, maybe you’re not in homeostasis, maybe you’re not in that manufacturing mode, maybe you’re in a cell stress and excessive inflammatory state, and in that situation, the deactivation of T4 to reverse T3 and the deactivation of T3 to T2 is probably on purpose.

Putting more T3 or more T4 or T2 into a system that’s trying to slow down its metabolism may not be in the best interest of the cells and tissues. 

So yes, when they do these mice and rat studies they do see that there’s some benefit, but if they have to take super physiologic doses of T2 to get those results, is that really realistic? 

And in a lot of those cases, they’re inducing a global hypothyroid state. A lot of people aren’t in a global hypothyroid state, or if they are, it’s from thyroid replacement. They’ve had enough T4 to replace the deficiency of what the gland can’t make, and they still can’t make it. So the model that we’re using in the lab is different than the model that you or I are in when we have our hypothyroid condition.

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T2 can do a lot of stuff, but T3 can do the same and is also at a higher concentration than we believe T2 is.

So the question to ask is what I’m seeing in my labs this inability to convert T4 to T3? Or when I’ve optimized my T4 and T3 in the blood with hormone replacement, and I’m still symptomatic, is this broken physiology where I just can’t bring T3 or T4 into the cell, or I just can’t convert T4 to optimal levels of T3?

Optimizing the blood doesn’t mean you’re optimizing the tissue, and we make this assumption that if I just put enough in the bloodstream, it is going to diffuse into the cells. 

But remember, the cells have the ability to regulate what happens to the T4 and T3!


So I don’t think supporting T2 in this state is going to optimize anybody’s physiology. It may be a bandaid, it may make you feel and function better temporarily, but ultimately the question is why aren’t you doing this the way it was intended without the extra supplemental T2? 

If you could do this for a part of your life and then all of a sudden you can’t, is the real root of your chronic hypothyroid signs and symptoms and all the other problems, a lack of T2 supplementation? I don’t think so.

And so my thoughts are that if you take T2 supplementation and you feel and function awesome, great, I don’t care. I don’t have any skin in the game. I’m not selling a T2 supplement. Even if there’s a supplement that I did develop and recommend, if I didn’t think it was appropriate, I wouldn’t recommend it.


If you take it and it has minimal impact, it’s probably not worth the money you’re paying for it, despite what any talking head says.

And if you have negative symptoms and you’re taking it, you probably should stop taking it because ultimately it’s not addressing the real issue. 

If you don’t have some type of excessive cell stress and you take T4 or your thyroid gland makes T4, it will convert that T4 into T3, and any of the downstream metabolites are going to be there. 

But if you’ve got some type of stress response that’s downregulating the metabolism of the cell adaptively, then putting more thyroid hormone, this metabolite T2 into the system may change the chemistry of the cell, but it may not be in the best interest of those cells and tissues long-term.


It’s important to know, despite what some maybe of the talking heads in our industry say, if you’re not converting T4 to T3, taking a whole bunch of T3 does not optimize your thyroid physiology.

If you take T4 and T3 and you still have a weight issue and chronic hypothyroid signs and symptoms, taking T2 won’t optimize your thyroid physiology. 

What optimizes your thyroid physiology is reducing the excessive cell stress that’s causing the adaptive downregulation of your metabolism.

That’s how you optimize your thyroid physiology, not by taking different types of hormone replacement.

You should also know that the doses in the T2 supplements on the market are way below what was used in the scientific literature on these rat and mice studies. And even in the few human studies that are out there, the amounts in a supplement are minuscule compared to what was used in those studies.


So, there is no shortcut. I wish there was a secret supplement or medication that’s going to fix your thyroid physiology, but there’s not. It’s a process. 

You’ve got to identify what’s creating your excessive cell stress response. Is it sleep? Is it emotions? Is it trauma? Is it bacteria? Is it viruses? Is it toxins? Is it a combination of those things and address and reduce those? When you do that, you improve your thyroid physiology and that’s how you optimize it.

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Hi, I’m Dr. Eric Balcavage, owner and founder of Rejuvagen. If you’re struggling with health issues or have questions, let’s chat. You can schedule a 15-minute call with me to get started.