Selenium, Thyroid Health & Mercury Detox

🔥 First, a Quick Heads-Up…

Tight28 is back July 6–August 2! If you’ve been feeling "okay, but not great," this program is for you. Tight28 dives into advanced topics like food sensitivities, inflammation, organ health, and how those invisible issues affect your weight, energy, bloating, joint pain, and even your mood—especially if you think you’re doing everything right.

💡 This is the only live round of Tight28 in 2025—and for some, it's the program that changes everything in just one week. 👉 Learn more and join us at www.tight28.com

🎧 In This Episode: The Hidden Hero Called Selenium

This week, we’re talking about something small but mighty: Selenium—a trace mineral that plays a huge role in midlife health, especially for the thyroid, brain, and metabolism. Here's how this episode came to be (shoutout to Tom, the neighbor with all the wild Alaskan fish 🐟)...

We cover:

• Why Selenium is essential for thyroid conversion (T4 ➡️ T3)

• How a deficiency can show up as fatigue, cold intolerance, and brain fog

• Its critical role in protecting the thyroid from oxidative damage

• How Selenium binds to mercury and helps neutralize toxicity (especially relevant if you eat a lot of fish)

• What the research says about Selenium lowering thyroid antibodies in Hashimoto’s

• Why two Brazil nuts a day might be the most delicious prescription you’ll ever get

• Foods rich in Selenium (besides Brazil nuts): wild fish, sunflower seeds, turkey, eggs, and shiitake mushrooms

• How too much Selenium can be toxic—why more isn’t better

• A sneak preview of the upcoming Mastering Midlife program (August!)

🧠 Key Quote:

“No Selenium, no thyroid conversion. You can have all the T4 in the world, but unless it’s turning into active T3, your metabolism is stuck in neutral.”

🎯 Takeaways:

• If you’re always cold, sluggish, or foggy—check your thyroid and Selenium status.

• Food-based Selenium is often enough, especially if you enjoy Brazil nuts or wild fish.

• Ladies in midlife and beyond: keep Selenium on your radar—especially if you have or suspect Hashimoto’s.

• Test, don’t guess. And remember: more is not better when it comes to trace minerals.

🎉 Final Reminder:

Tight28 starts July 6—your chance to uncover hidden blocks like inflammation, organ dysfunction, and food sensitivities that may be sabotaging your progress. 🔗 www.tight28.com — let’s fix what’s really going on behind the scenes.

📍Share this episode with someone who loves fish, Brazil nuts, or just wants to stop being tired and cold all the time.

Episode Transcript

(00:10):
Hey there, listeners.
I am Joanne Lee Cornish, your Truth Bomb Dropper in the world of weight loss, body composition, and mastering the art of rocking the body you've always deserved and dreamed of in midlife and beyond.
Let's cut through the noise.
Society tells us it's downhill from now on.
We're told to embrace the middle age weight gain, embrace the muscle loss, and poor health.

(00:36):
If that's your vibe, then cool.
But if you're ready to defy the narrative, then I am your gal.
This podcast is.
A No Fluff podcast where we break down the essential truths of body composition, toss around some practical tips, and dissect the latest trends.
I'm not here to sugarcoat.
I'm here to show you what's not just possible, but down, out probable for you.

(01:02):
If you enjoy this content, be sure to click the link in the show notes to explore how we can team up and kick mediocracy to the curb.
I offer one-on-one coaching my ever popular group coaching programs and my corporate Educate to Elevate program.
Okay, let's get on with the podcast.
We wanna talk about Selenium.

(01:23):
I haven't done a showcase supplement for a while, and I'll tell you how this came about.
So.
We were out outside in our patio and our neighbor was there, Tom.
So I'm talking to him in the backyard.
It's always weird for me saying yard.
'cause in England it's a back garden, but America, it's a backyard.
It's not a yard, it's not concrete.

(01:43):
It's got grass on it.
It's a garden.
Anyway, so I'm in my garden and Tom, my, my neighbor's there, uh, in the parkland we have behind the house.
And Richard chatting and he's saying how he follows me on Instagram.
I'm like, dude, you gotta come over to the podcast.
I don't really do any much on Instagram.

(02:03):
There's really not much you can do on Instagram.
So Tom, this is for you.
Tom and I were talking about, he was talking about he was going up to Alaska and fishing and the great fish he was getting and, and um, he was asking me about krill and did I take krill, which I don't, but I know why people take krill 'cause it's the, a bottom feeding fish that this has got less mercury.

(02:27):
And he was concerned.
He is getting all this fish from Alaska and it's fantastic but gotta be careful with the mercury.
And I brought up selenium.
I'm gonna save that, but that's how this podcast got started.
So I thought let's talk about Selenium because, um, it's a trace mineral, but it really doesn't get discussed as much as it should because now we're talking about thyroid function, um, detoxifying, uh, mercury, and how easy it is to supplement selenium without even getting a supplement.

(02:57):
So let's talk about, first, let's talk about thyroid.
And you know, I deal with a lot of people in midlife.
That's if I've got a niche, I guess that's it.
Even though, you know, it seems to be doing pretty good with the teenagers right now, but it comes up a lot.
Thyroid function comes up a lot.
Anybody over the age of like 35, and it's a big deal be because you might, your thyroid controls your metabolism, your energy levels, your temperature regulation, and even your mood.

(03:28):
I know for me, when my thyroid was, uh, a little under par, it showed up as, um, what, what do they call it? Uh, resistant to cold.
Anyway, I, I was always cold.
I was sitting in my, uh, nurse practitioner's office and it's like September in Idaho, which means it's like two degrees colder than hell, and.

(03:55):
I'm in a sweater and she, she's like, are you cold? I'm like, I'm always cold.
I'm just always cold.
And she said, oh my gosh, I bet that's your thyroid.
And it was so, yeah, so thyroid metabolism, energy level, temperature control, and even your mood, I.
And Selenium is a key player in how your thyroid works.
Specifically Selenium helps convert T four Thyroxine, which is inactive into the T three, which is the active form of thyroid that your cells actually use.

(04:25):
So let's back up a little bit and be clear about this.
You have produced thyroxin T four, it's inactive.
Your body can't use it, and it's converted by an enzyme into T three, the active form that your cells can actually use.
So this goes for cortisol.
Um, you, you know, there's other hormones are an inactive in the converted into the active form.

(04:50):
Uh, some people with elevated cortisol, there's some really cool supplements, even green tea.
Can, can block the conversion or lessen the conversion into the active form of cortisol.
So that's pretty cool.
And, and with thyroid, you know, you might have an abundance of T four, but unless it's converting into the active form of T three, you know, you could be pumping out T four all day, but your cells aren't getting any of it, any of the active form.

(05:18):
So again, if you're reading your blood work.
It's, oh, is your thyroid good? Well, which part of your thyroid you know, is your thyroid stimulating hormone good? Is your T four good? And if your T four's good, is your T three good? You know, so there can be, when we get to problems with the thyroid, it can with, with thyroid stimulating hormone, it can be with T four, it can be with the amount of T four, it can be the conversion to T three, it can be reverse thyroid.

(05:48):
Uh, I realize in saying this out loud that I now have to do a podcast just on thyroid.
But, so for right now, let's just talk about note to self.
The fact that the conversion, we have an inactive thyroid T four, we have to convert it into an active form of T three, and Selenium helps that with that conversion.

(06:10):
Um, so the conversion happens thanks to an enzyme.
Well, enzyme's called ID dio, which I hate saying.
But these enzymes that convert inactive to active are selenium dependent.
So no selenium, no conversion.
Yeah, so that means fatigue, brain fog, sluggish metabolism, you name it, feeling cold, et cetera, et cetera.

(06:38):
Selenium also protects the thyroid from, uh, oxidative damage.
Now, why is that important? Well, the thyroid is the most selenium rich organ in the body, partly because it needs protection.
So when the body is producing hormones.
It can get kind of messy on a cellular level, it can cause a bit of a mess.

(07:00):
And that mess is called, uh, called free radicals.
And what happens is then we have things like called antioxidants, which come and utilize the free radicals.
So think of it like, you know.
A factory making stuff and there's all these byproducts and there's all this dirt that goes along with ma the production of energy or something and, and then, you know, the anti, the antioxidants come along and, and clean the mess up.

(07:26):
So with why Selenium is so good, because it, it kind of, uh, is part of.
It's part of the cleanup.
Let's put it like that.
So Selenium is part of a powerful enzyme called, uh, glutathione peroxidase, which acts like a fire extinguisher inside your cells.
So it puts out the fires, it, it gets rid of the mess.

(07:48):
Now this matters.
So it's protective of the thyroid.
That's what I'm trying to say.
It protects the thyroid from, from damage caused by, um, free radicals, which are caused by, you know, just producing hormones in the byproducts of that production.
Who does that meet matter even more to well.

(08:12):
If you've got Hashimoto's.
So Hashimoto's is the most common autoimmune thyroid condition.
And I would say in the last month, I've, I, I've talked to three people with elevated, uh, thyroid antibodies, which is suggesting Hashimoto's, and it is pretty common with ladies of a certain age.
Um, so if you've got Hashimoto's or if you suspect you have Hashimoto's, the studies are showing that Selenium can reduce thyroid antibodies.

(08:41):
Let's say that again.
Supplementation of selenium can reduce thyroid antibodies in people with Hashimoto's.
Now the studies combined Selenium with Myron Inital, which is another supplement, but I'm gonna save that podcast for another day.
But if you want to take a note, if you have got Hashimoto's, you know it.
It says Selenium with Myron Insole, not just insole.

(09:04):
It's myo insole.
Okay.
Solenium, super important for the thyroid, protecting the thyroid from, um, free radicals, and very important for the conversion of T three, T four into the active form of thyroid, which is T three.

(09:24):
What about my conversation with Tom? So Tom and I were talking about Mercury in Fish, and you probably heard things like, well, don't eat too much.
Chew the Mercury, or, and yes, mercury is a neurotoxin.
It messes with brain function.
Um, it messes with thyroid and it messes with a whole, whole bunch of other things.
It's certainly not a good thing.

(09:47):
But this is the twist.
Most ocean fish also contain selenium, and in many cases, that there's enough selenium in the fish to neutralize the mercury.
Now, I love this because this is just, again, mother nature doesn't get it wrong.
She just doesn't.
And so we're saying, oh, well fish, fish is bad for us.

(10:09):
Oh, there's too much mercury.
Like mother nature's already taken care of that to an extent.
Uh, because of the selenium.
How, how does Selenium then neutralize the Mercury? So Selenium binds to mercury forming a complex that the body can't absorb or store.
So in other words, when selenium is present, insufficient amounts, it cancels out mercury's toxic effects because it binds with that mercury.

(10:36):
So kind of cool.
And like I say, I just think it's just another example of how miraculous our body, our bodies are, you know? So unless you're tearing down on swordfish, like it's full-time job, moderate amounts of fish consumption, especially.
Um, wild salmon, sardines, even tuna once or twice a week.

(10:58):
You know, the benefits far outweigh the risk, but I, I will preface that by, I should preface that by saying quality counts.
So, you know, Tom's up there getting that fish from Alaska.
Yo Tom, bring me some back.
Um, but yes, with my blessing and with my advice and suggestion, eat it.
Um, and enjoy now.

(11:22):
Can't get too carried away because Selenium is a trace mineral and that word trace is doing some heavy, heavy lifting here because if you have too much selenium, it is toxic.
We are talking nausea, hair loss, brittle nails, neurological symptoms.
Um, in extreme cases, and I mean extreme cases, it can be fatal.

(11:46):
So what's the sweet spot there? The sweet spot is about 55 micrograms per day.
Uh, I think that's the RDA for adults.
Not that the RDA means much these days, but, um, pot fish, five micrograms per day.
Uh, um, I mean, most supplements are higher than that.
They, they usually a hundred to 200 micrograms.

(12:06):
I would, I would be.
I would never mega dose unless some doctor specifically tells you to, but 200 micrograms, uh, a day will absolutely suffice and that's what most supplements co come with.
But here's a better part, just two Brazil nuts a day will give you your entire daily selenium needs and sometimes a little bit more because isn't there such thing as two Brazil nuts? It's like two equals four equals.

(12:37):
So anyway, but.
Um, one Brazil nut can cont contain anywhere from 68 to nine 90 micrograms of selenium.
So I think it depends on where it's grown, but you know, two, maybe three is plenty.
So that's a super, super easy and very fun way of getting a little bit of selenium in your diet without just popping in another pill.

(13:00):
What if you, what if you're allergic to nuts? What? What if you are just.
Not your thing then wild caught fish, especially sardine salmon and tuna are great.
Source of selenium.
Eggs are a great source of selenium.
Ooh, what else of, of, of, um, I guess lean meat, Turkey chicken.
Um, sunflower seeds.

(13:20):
Sunflower seeds.
Uh, and um, what else? There's another one.
Shiitake mushrooms.
There you go.
Uh, are are great forms of selenium.
So yes, you can take a supplement.
Um, the food, it kind of depends on the soil.
So, you know, nutritious soil is, produces selenium rich food.

(13:46):
Um, but unless you've got a problem with Brazil nuts, unless you've got an allergy or something, that to me would be the best way.
Alright.
So let's bring this together, keeping this podcast short, keeping this podcast short and sweet.
Here's the deal.
If you have Hashimoto's low, T three, if your blood work even shows low selenium that can do that, then um, supplementation maybe.

(14:16):
Helpful, helpful, but test, don't guess, uh.
Too little Selenium is a problem, but too much is worse.
Please remember that.
It's, it, it would be toxic.
Two three Brazil nuts.
You know, 200 a day is fine.
More is not better.

(14:36):
So if you're just trying to keep your thyroid, um, you know, humming along there, your brain shop, um.
Temperature control.
Uh, for me, when, when my thyroid showed up, it was a bit iffy.
It was, I was cold all the time.
I went to meet my nurse practitioner and it was September in Idaho, which is oh two degrees shy of hell, I think.

(14:59):
And I'm in a, I'm in a sweater, I sweatshirt.
It's like, you cold.
I'm like, I'm always cold.
And once I'm cold, I don't warm up.
That's, and she's like, yeah, it's your thyroid.
So that was interesting.
So again, test, don't guess.
Uh, ladies, uh, thyroid issues are, are, are, are pretty prone, pretty pretty, um, sorry.

(15:24):
Women can be pretty prone to thyroid issues.
It can also, you know, thyroid issues can come up with, I mean, it's totally misdiagnosed in nursing homes and.
You know, in talking about this, I actually think thyroid deserves its own podcast.
So I'll, I'll keep it on Selenium right now, but I'll just say, watch out.

(15:45):
I'll do a full podcast on thyroid because, um, thyroid is really undiagnosed as we get older.
I think they say.
Uh, 25% of people in nursing homes have got undiagnosed, uh, thyroid issues.
And what that shows show, uh, shows up as, as is fatigue, constipation, dry skin.
Well, you know, when you're older, you know that you think that's just part of aging.

(16:10):
If you're younger, you probably think, wow, something's not right here.
And you might get tested.
But when we're older, oh, you're tired.
You constipate, you've got dry skin, whatever.
Uh, so it, it can go really undiagnosed.
So thyroid issue.
Um, I talk about thyroid a lot in the Mastering Midlife program, which will be coming up in, and when I call it the Mastering Midlife program, it's midlife and beyond.

(16:36):
You know, I had one lady, she, she asked me if she could join 'cause she was 70.
I'm like, oh my gosh, this is, you know.
I like to say my Mastering midlife program is if you're approaching it, dealing with it or the aftermath of it.
It's a pretty good program.
But before we get to that, because I'm gonna do a master in midlife in the end of August before we get to mastering midlife, I am, we're kicking off the tight 28 program and that that kicks off on July the sixth to August the second, and.

(17:09):
That that one is, that program is the least attended, which makes me laugh because it's the, actually the program, when I get the fastest results in the shortest amount of time, in terms of, a lot of people get super great results in week one.
But it's, it's about food sensitivities, uh, organ health, and basically.

(17:30):
When, when your body composition gets stuck going beyond the macros.
So, and, and things like bloating, fatigue, joint pain, stubborn weight.
You know, if you have a cheap meal and gain six pounds and you know, that shouldn't happen.
Uh, so that's the tight one.
You tight.
I can't talk today.
The tight 28 program, we start July 6th.

(17:54):
I deliberately put it after July 4th for obvious reasons.
The Selenium, uh, great supplement.
Under discussed, but actually very easy to get an adequate amount without even taking a supplement.
We can just get it from, um, a couple of the very fun Brazil nuts.

(18:16):
Okay, that's it for now.
Short and sweet.
Hi Tom.
I hope you're listening.
I do hope you enjoyed this episode of Midlife Mayhem.
Be sure to subscribe and be sure to tell your friends about this wonderful podcast.
If you would like more of me than on social.

(18:37):
It's simple.
Just my name at Joanne Lee Cornish.
I.
Uh, also my website, the shrink shop.com,
where you can see all my coaching programs.
There are many, many ways we can work together.
Obviously I do private one-on-one coaching.
I do the, all my programs are in a self-study form and all my programs are run as a live program at least once a year.

(19:03):
I try and do twice, but it usually ends up being once I have, um.
Mindset program.
I have my awesome five JP creek shred that people love.
I have the signature weight loss program.
I have Type 28, which is advanced weight loss.
I have, uh, muscle, uh, mastery, and I have midlife, uh, mastering midlife.

(19:24):
So six programs that offer a progression to fully understand the body composition through the ages.
If you have questions, if you're kind of wondering how I can help you, then simply shoot me an email.
At [e-mail].
Tell me what's going on and I'll get back to you and let you know the, the way I can help.
Okay, that's it for now.