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Iodine for Hypothyroidism: Crucial Nutrient or Harmful Toxin?


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This article is part of a special report on Thyroid Disorders. To see the other articles in this series, click here.

In a previous article I showed why, when used alone, thyroid hormone replacement often fails. In this post I’ll explain why optimizing your iodine intake is so crucial, and why both too little and too much iodine can be harmful.

Iodine deficiency is the most common cause of hypothyroidism worldwide. Once researchers realized this, health authorities around the world began adding iodine to table salt.

This strategy was effective in correcting iodine deficiency. But it had an unanticipated—and undesired—effect. In countries where iodine has been added to table salt, the rates of autoimmune thyroid disease have risen. The following is just a sample of studies around the world demonstrating this effect:

Why does this happen? Because increased iodine intake, especially in supplement form, can increase the autoimmune attack on the thyroid. Iodine reduces the activity of an enzyme called thyroid peroxidase (TPO). TPO is required for proper thyroid hormone production.

On the other hand, restricting intake of iodine can reverse hypothyroidism. In one study, 78% of patients with Hashimoto’s regained normal thyroid function with iodine restriction alone.

However—and this is a big “however”— it appears that iodine may only pose a problem for people with Hashimoto’s and other autoimmune thyroid diseases in the presence of concurrent selenium deficiency.

In the study above where rats developed goiter while receiving excess iodine, when they were given adequate selenium they did not develop the goiter.

Other studies have shown that selenium protects against the effects of iodine toxicity and prevents the triggering and flaring of autoimmune disease that excess iodine without selenium can cause.

In my practice I always test for both iodine deficiency and Hashimoto’s when a patient presents with hypothyroid symptoms. If they are iodine deficient, I will start them on a trial of iodine and selenium together. In most cases, patients see a significant improvement. In a minority of cases, they cannot tolerate supplemental iodine even with adequate selenium intake.

Unfortunately, the blood test for iodine that your doctor might run is not very accurate. The best way to determine iodine status is with a 24-hour urine loading test. This involves taking a large dose of iodine and collecting your urine for 24 hours afterward. If you are iodine deficient, you’ll retain more of the ingested iodine than you should and the level of iodine excreted in the urine will be lower than expected. The two labs I recommend for this test are Doctor’s Data and Hakala.

That said, if your doctor or health care practitioner won’t order these tests, you can simply begin an iodine protocol. This involves starting with a low dose of iodine (I start my patients with kelp tablets that contain 325 mcg of iodine per tablet) and increasing very slowly over time. As I’ve described in this article, it’s crucial that you also take 200 mcg of selenium per day during this protocol to protect against the potentially adverse effects of iodine supplementation, especially if you have autoimmune thyroid disease.

Physicians that specialize in treating hypothyroidism with iodine (such as Dr. Abraham and Dr. Brownstein) suggest doses as high as 50 mg per day may be necessary to restore iodine levels in those that are deficient. I have used doses this high in my practice, but it’s imperative that patients build up to such high doses very slowly, and I don’t recommend doing it without the supervision of a clinician experienced with iodine treatment. Be aware that high doses of iodine can lead to a transient increase in TSH levels, which can be mistakenly interpreted as a sign of hypothyroidism.

Finally, it’s important to keep in mind that a minority of patients with Hashimoto’s confirmed by biopsy (the gold standard) never test positive for thyroid antibodies. This is probably because their immune systems are so depressed they can no longer produce antibodies. If you have a combination of hyper- and hypothyroid symptoms, I would still suspect Hashimoto’s even if your thyroid antibody tests are normal. It’s wise to be cautious with iodine if you have any signs of autoimmune thyroid disease, even without a confirmed diagnosis.

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  1. Thank you for this information. I’m planning to start taking selenium & I’ll be happy to share with my Hashimoto’s followers.

  2. Hello Dr. Chris. You wrote:
    “Other studies have shown that selenium protects against the effects of iodine toxicity and prevents the triggering and flaring of autoimmune disease that excess iodine without selenium can cause.”

    If excess of Iodine causes the triggering and flaring of autoimmune disease of the thyroid, how do you reverse the situation? Stopping Iodine intake I presume, but what next? Does consuming selenium and other nutrients help reverse the autoimmune disease?

    • Take a look at the book: Iodine: Why You Need It, Why You Can’t Live Without It by Dr. David Brownstein. It might answer more questions for you.

  3. https://books.google.ca/books?id=FBdk5SkdNZAC&pg=PA24&lpg=PA24
    “Iodine and Inorganic Iodides: Human Health Aspects”

    This reference contains a summary of a bunch of research—nothing seems to support the high-dose iodine that is advocated online.

    I know lots of healthy people who don’t take vitamins, who don’t really do much other than eat like their mothers taught them, which involves a balanced diet rich in delicious foods.

    Excessive iodine may be harmless, but a study on peace corps members indicated that 46/96 had enlarged thyroids, 29/96 had elevated TSH and 4/96 had depressed TSH while consuming 50-90mg Iodine/day, which is the range that some “internet doctors” like to suggest, along with the ridiculous suggestion that any horrible feelings this causes are “detox.”

    Iodine insufficiency is, in my view, very rare. One of my hypotheses is that phosphorus deficiency is actually sort of common, especially amongst obese/doughy women who consume low protein, high carbohydrate diets. Now, let’s say that a smart body had sufficient iodine but insufficient P, what would it do? I think it would depress thyroid function, because if it didn’t, it would mean that the body would have to start tearing itself apart to get sufficient phosphorus to drive the metabolism.

    Ca/Mg metabolism is, in a few animal studies I don’t have at hand, altered by Si, which is likely an essential mineral which people don’t necessarily get enough of. Boron is also implicated in Ca metabolism, likely as an essential nutrient. And then sulfur, well, low protein high carbohydrate diets may be deficient in sulfur, so, again, what is the body going to do to preserve sulfur but slow itself down, because the only way to provide enough in a case of insufficiency would be to eat itself, which is rarely a good idea—the body is not entirely as stupid as many people are.

    In nature, I don’t know of any land mammals that eat the amounts of iodine being suggested, but there are plenty of land mammals who eat more protein than your average doughy/skinny-fat hypothyroid woman eats. I also don’t think these sorts of disorders are common amongst dogs or primates in zoos, who are fed a fairly standard chow.

    Even a few hundred mics can impact susceptible individuals negatively. Given the fortification of salt and the presence of iodine in dairy products, I am just not sure about what is more likely, I deficiency or phosphorus deficiency. One source I have says that a cup of milk is just under 60ug I, so two cups of milk a day and you’re pretty much there, along with 480mg P, a good chunk. Taking 150ug (or 1.5mg, etc.) supplemental iodine with inadequate phosphorus, I have no idea how that is supposed to drive metabolism.

    Phosphorus is well tolerated up to 4g/day, tho for some reason it doesn’t make it into supplements, probably because of how bulky it is. There are studies using > 1g supplemental P a day for obesity, etc.

    Eating a diet inadequate in “macrominerals” is never going to be corrected by megadosing on trace elements.

  4. I can not believe the amount of ignorance being posted between everyone. Do you not understand everyones story/body/etc is different? Do you not understand not every doctor is a cookie cutter, not every medication is fool proof? Im 36 years old. I was diagnosed with graves at 17 I have taken the advice and medications of 12 different doctors from Rhode Island to Boston ALL the way to Phoenix Az from age 17 to age 26 before finally being told in 2007 that i was going to DIE from congestive heart failure with in 3 months if i did not have my thyroid removed due to all the thyroid storms i have had over those years of doing exactly what i was told by my doctors. So i had the surgery. THAT RECOVERY SUCKED! Still after followed all the rules, synthetic hormones, calcium supplements, blood work, constant up and down of medicine. Finally i said FORGET IT. I would rather feel the way i did then to keep playing tug of with meds and drs. It sucks to throw your hands up and think well shoot this is now my life. Then you live life, kids, work, family, and you push it farther amd farther down the list. Till holy crap its 10 years later and you feel like your half dead! And maybe if your lucky you have time to start trying to fix it all over again and realize its worse now with all these doctors who believe they know EVERYTHING better than the next some telling you youre fine, some wont touch you, others get mad you havent been admitted onto a hospital. So you reach out to other woman for some sort of support or a glimmer of hope. Only to be bashed on cause you asked a question. You SUCK! So come on all you know it alls! All you who have only been dealing with this for a minute rather than almost 20years like alot of us. You have all the answers? You have all the knowledge and wisdom? Bring it on. Tell us what it is we need to do to all be healed. To feel even 1/3 better to be able to make it threw a complete day and not feel like a failure to our jobs, our children, our spouse, our homes, our SELVES! Cause my Jesus knows everyday how awful i feel when im trying turns into i can’t. And i know how awful i feel when that pregnancy turned into it cant!

    • oh Elissa…i am so sorry the pain and agony you are going thru in all areas… the one thing you did say here..is Jesus and i will keep you in my prayers…because He is the Only One who hears our cries and comforts our hearts… i can feel just a pinch of your pain through your words and you are in my prayers.

  5. Hi Chris and fellow readers! Just an interesting observation.
    I became infected by Helicobacter Plyori in 2009, and it was undiagnosed for more than 6 months. It wreaked extreme havoc inside my digestive system, in conjunction with repeated bouts of strong antibiotics. That was the beginning of my long ‘ill-health journey’. Two years ago, I became infected by Helicobacter once again.. It has caused so much damage that I’ve now developed autoimmune disease, in the form of Hashimoto’s. Point being – I received the diagnosis by a wonderful Integrative Dr here in Adelaide, Australia (actually she has done some training through Chris Kresser!) She put me onto the 30 day AIP Paleo reset diet. I was also taking a supplement that contained iodine. Prior to starting the diet and supplements, I was getting extreme head spins and giddiness everyday. Balance issues, chronic fatigue, a strange feeling of heavy legs/feet, and just a general feeling of not being in control of co-ordination. It appeared to get worse when I began the Autoimmune protocol. I wondered why I was actually feeling worse during the 30 day reset, instead of better. I know that of course the start of any extreme diet is always going to feel worse, before it feels better, so that was always understood. But this was different. It felt ‘out of place’ and separate to the beautiful, clean diet I was eating. As though something else was causing these particular symptoms. I caught wind of this article above, and wondered if perhaps taking supplements containing iodine was in fact hindering not helping. Especially since I do also use a lot of Pink Himalayan salt on my food, for iodine. I ceased taking the supplements, and within about 4-5 days, the symptoms notably began to decrease. Within 1-2 weeks, they were completely gone. Now who’s to say it wasn’t sheer coincidence that my symptoms began improving once I stopped the iodine? Maybe those symptoms would’ve dissipated anyway, even if I hadn’t stopped the supplements. Who can know! But it was just very interesting to note that those particular symptoms quite quickly began to subside, once I removed iodine from my regime. Food for thought.. 🙂

    • I learned about bone broth its really healing to the gut a d most illnesses dtart from the gut. Bone broth is such a miracle for autoimmune disease which i have. I hope this helps. Im still learning and it also helps to use ghee or Talo to cook with and to make your own bone broth with vegetables .like a stew in a crock pot or pressure cooker maybe.i like slow cooking n not killing the veggies so there is a right way to cook n prepare. Im learing still . Hope this all helps. I want to see EVERYONE GET CURED AND BR HAPPY N HEALTHY. ♡

  6. Can you possibly discuss your kelp dosing protocol? I had no idea it was ok to increase beyond say one cap a day (300 micrograms). I’ve been trying to kick start my Thyroid after I was semi hypo and with a low idodine levels. I’m 45, and super athletic but was feeling super awful.

    It began with labs that showed a TSH of 3.160 T3 2.5 and T4 .80. My naturo went straight for wanting to give me Thyroid med to correct (I had all the telltale symptoms) but I was suspicious of my idodine (I had cut out eggs due to am intolerance, and don’t consume iodized salt, nor any other proper sources for the last 8 months).

    Sure enough my iodine (although it was just a straightforward UA) revealed it was very low at 13. I had only tried a half grain of natural Thyroid for about a week (began it about a week before the iodine test) but I didn’t realize taking the meds would shut down my Thyroid! So I quit any glandulars and began iodine in kelp caps just one a day 300 mcg and iodized salt thinking (intuitively) this may have been why my Thyroid was malfunctioning.

    After about 4 weeks just got new results on Thyroid tests and they are TSH 2.830 and T3 is 2.4 and T4 is .82. I think maybe the idodine could be the ticket! Maybe?? Would love to learn more about the dosing protocol you use though. I’m sure it can be different for each individual but any info would be great!

    • U need to take sellenium with the iodine so your not being attacked. ♡bone broth is a major help to the gut where most illnesses begin. Ghee and Talo help to cook vegetables they with heal your gut and seal it. Leaky guts cause this to get worse as well .its so many symptons n a some things causing it in the first place. Gut ,your sellenium n iodine. Etc… im still learning. Im so amazed by these foods.hope this belps and you get healthy cured n are happy about life♡

  7. Hi Chris, I’ve been avidly listening to your podcasts and in them you suggest leaving a comment about who we, the listeners, think may make an interesting interview for the podcast.
    I would be very interested to hear a conversation with Dr Brownstein. I have hashimoto’s and have recently started the iodine protocol and it has been a breakthrough for me.
    Thanks for all the brilliant podcasts.

  8. Anyone here has ever had TSH increased after taking Iodoral/SSKI (12.5mg dose and over)?

    In my case, after taking 32.5mg of SSKI fo r 6 weeks, my TSH went up to 9.3.

    Please feel free to comment.

    • I developed antibodies and goiter after about 6 weeks on iodoral, 50 mg I believe. I was on 400 mcg selenium concurrently.

      • What were the symptoms? Did you feel pain while swallowing and such? And how did you get better? How did you reverse the condition? I presume you stopped taking Iodine. How long did it take you to get better? I would really be grateful if you would tell me more.

    • Hi Ruth..i find this puzzling myself as my TSH level increased as well and according to this website, as stated above, it is to be expected….they don’t say why though; my Md will have a cow if my level stays this way for a lengthy time…says it’s not good overall. i also find it puzzling on this website, that others post a question to Chris, but we don’t see the response from him; does he respond to them individually or overall??? does anyone want to comment on this?? if he does..great! if not, ??? thanks.

    • I don’t know what all those numbers are but I take iodine supplements and I felt fantastic. I tried a different brand this time but wellnessresource.com has iodine drops and I felt awake and clear headed and energetic. Ive ordered some more but any brand is good I just prefer there’s. I stopped being cold and slow and irritated.
      And of course with more energy you can exercise more and with more exercise the faster you are burning the fat from before you knew you had hypothyroidism. I gained over 100lbs. And the meds helped but that iodine has sped it up.

    • After my thyroid numbers being stable for years on same dose medication after I started taking very low dose of potassium iodide my TSH went up and FT3&4 went down. Stopped taking iodine of any kind other than from foods.

  9. Hello,
    One of my friend recently detected hypothyroidism and is facing symptoms like weakness , weight gain and hair loss and she is very much tensed about these factors. Please let me know what are the other risk factors that can come for hypothyroidism and what supplements aur tablets can she take for further care.

    • WellnessResources.com has iodine drops. They’re fantastic, it filled in the gaps that the synthetic hormones can’t fill.
      Also take hair and nail vitamins or even prenatal vitamins to help the hair regrowth which will improve with the meds and supplements but it helps speed it up.

      • I learned about bone broth its really healing to the gut a d most illnesses dtart from the gut. Bone broth is such a miracle for autoimmune disease which i have. I hope this helps. Im still learning and it also helps to use ghee or Talo to cook with and to make your own bone broth with vegetables .like a stew in a crock pot or pressure cooker maybe.i like slow cooking n not killing the veggies so there is a right way to cook n prepare. Im learing still . Hope this all helps. I want to see EVERYONE GET CURED AND BR HAPPY N HEALTHY. ♡

  10. My story is long and boring but I’ll try to make it as short as possible… I kept going to my PCP for fatigue and hair loss. I was turned away with antidepressants and a referral for a sleep study after multiple blood tests revealed nothing. I did notice my WBC were low and the doc told me I could go to a hematologist if I wanted to. Because I was still feeling so bad I took her up on it. It was there that the hematologist told me my ferritin was really low (13) and taking iron supplements might be life changing. I’ve suffered through the supplements and gotten better but am still not 100% as far as energy level. I found an integrative doc to replace the MD who never found anything wrong for obvious reasons. The new place doesn’t really like to discuss my iron but likes to obsess over my thyroid. All thyroid tests are normal by regular standards. TSH- 2.3, FT3- 2.7, FT4 1.02. Last year I was given the teeniest dose of naturethroid and it made me feel like I was having a heart attack after just over a week of taking it so I stopped. During my most recent visit I was told my B12 was too low at 316 and I probably have MTHFR. My ferritin was barely discussed at 36. Again with the thyroid and I was offered meds again which I declined. So instead I was told to take 60mcg selenium, 50mg zinc, and 200mg of IODINE… Yes MILLIGRAMS. Is this safe?!?! I’ve never been tested for an iodine deficiency. And I’ve never had anyone try to figure out why my iron and B12 are usually low. Time to find a new doc?

    • Why would you not take the medicine? That’s really not smart. You can’t come on here complaining about how bad you feel but then refuse to take the simple hormone once a day?
      I have hypothyroidism and the pills work. I lost 70lbs already. Because I took my medicine and my energy came back and I was able to excercise again. And my hair grew back.
      But I guess you like the attention from being sick? Cause I can’t imagine any other reason you would refuse meds that solve every problem you took 2 pages to complain about it.

      • No need to be harsh. Did you not read the part where they are confused as to whether or not thyroid hormone is justified, since their labs are in range? And did you miss the part where they were given a test dose, but did not tolerate it? You’re projecting your results into another person, and assuming they will be in the same situation.

        • Yeah I’ve also noticed alot of middle aged women between 25 and 45+ enjoy being sick and when offered options they say they “can’t tolerate it” so they can keep the little going.
          I knew a woman that needed to take thyroid meds and wouldn’t do it because it made her nauseated.
          I don’t know kw. I’m 200 ponds overweight I’m gonna take a lull that will help and suffer a little tummy discomfort.
          So far the meds have helped me Lise 100 pounds.
          I’d be on that. But to each their own.
          She never said what she meant by can’t tolerate it? What. It made her break out in a rash? It made her vomit or walk funny, like. How did her body not accept it? It’s a synthetic hormones. There’s not much for it to do that’s not any worse than what she’s already got.
          Some people like being a medical mystery. Makes them feel special.

          • I take my meds and am in range but still have EVERY symptom… the meds alone don’t work for everyone for everything. I don’t think anyone wants to feel sick to get attention. Maybe you could try feeling a little more sympathetic here. She’s obviously attempting to get better or she wouldn’t have found this page. Nor would I, I’m looking for alternatives because I’m not ok. I’m not who I know I was before everything went wrong. And a lot of us would rather find a natural solution and not be at the mercy of the pharmaceutical companies.

            • Why are you attacking each other??? As women, we need to unite and stand together, not break each other down. Best wishes to all of you.

              • My aunts like to play up their symptoms of hypothyroidism for attention and sympathy.
                I have hypothyroidism and it took a few tries to get the dosage right with minimal side effects.
                I gained 100lbs and I was going to put up with any side effects as long as it fixed my metabolism as I do competive weight lifting and need to weigh x amount of weight to win stuff.

          • It highers your cholesterol. May be that’s how your “friend” responded to those side effects? She felt worse if she had it in her system may be because of that? There’s always going to be side affects. Some people respond differently to medication and it ruins your liver. 🙁

          • She did say it made her feel like she was gonna have a heart attack. And i have hashimotos for 9 yrs now. Yes the meds will not work as great as they used to after a while. Why are you so nasty to her. I also have breast implant illness i had breast implants for 12 yrs and have been sick the last 10 yrs. I am now gonna be 36 and have been sick since 25. I absolutely do not like being sick i have no life im severely depressed
            And i am a a faliure at being a parent and a person. How good does that feel? Sounds like your the miserable one

        • Only. One test dose? It took me like 5 test dosages to get it right.
          See, I like that it’s modern times with modern medical knowledge and technology and there’s multiple medications to help solve my problems cause 100 years ago Wed all be screwed.
          And I have hypothyroidism myself, and as I stated in the replies down there, I have relatives that like to play up their hypothyroidism for attention and sympathy.
          It makes me mad when people refuse medicine then complain OK? Little store bought vitamins are not going to do a thing for thyroids.otherwise they wouldn’t have invented like, actual medicine that’s FDA approved and real and not a big lie made to make you hand over money.

      • That was a mean disrespectful answer. I’m sorry if you were not taught kindness but as an adult I’m sure even you know you could of been kinder.

        • I have hypothyroidism and I wanted to fix it. It took multiple times to get the dosage right. And it runs in my family and my aunts like to make themselves sick for attention.
          Yeah it’s retarded but I’ve known too many people that enjoy illness because they like the attention and sympathy

      • You are not a nice person. Do not post if you are going to be so insensitive to someone trying to find answers and support. Please stay off blogs.

      • thats nasty Morna –

        do you like being mean?

        get steppin,your attitude isnt wanted here

    • lauren– i hope you will continue to read these posts and all over the board on different issues/subjects to see if you can try to piece together what may help you; please don’t take others’ negative comments personal…they haven’t walked in your shoes and we all don’t know your full story (sometimes we write a short story and have left out vital info and others jump on it)..don’t take it personal..just move on to the next comment and get a paper and pen and jot down all the info you can. i will keep you in my prayers.

      • I’m not negative. I’m just real. She tried one time and little vitamins and minerals are a waste of money. I was willing to be patient and find the right dosages and prescriptions right.
        If you want to get better you’d try. She’s just bitching. I have hypothyroidism and it never occurred to me ever to refuse medicine for it. It’s a given you are going to have to be patient and test things for the long term.
        I have relatives that enjoy playing up their hypothyroidism for attention and sympathy. They will refuse their meds and then cry about how bad they feel.

        • we don’t know what others are going through; all we know is ourselves…share what you know to be helpful and in a nice attitude and it goes a long way to help someone else; sometimes our best advice is to listen and be kind..pass on what you know is working for you and move on; others can try or not..it’s up to them. that’s all i’m saying. this world beats you up, why not be nice to one another. God bless you abundantly Morna! 🙂

        • I think Morna has an important point of view to be aware of, especially as some of us are just on the brink of discovering thyroid conditions, as myself.
          I have lapsed between what to do; I have raced to buy iodine drops and selenium to beat the onset of something worse.
          In my first and only dose of those minerals, I felt dizzy flashes but then later on a feeling of clarity in mind and sight and I was more alert and able to withstand reading before bed. I still don’t trust it and I’m still complaining – she’s right and you’re right – we have to be honest with ourselves and make a hard decision. I’m really confused. These discussions help, even the not so perfectly sensitive perspectives, thank you for sharing.

        • How can you be so cruel? I’ve been struggling for years as there are so many variables that come into play. It’s great that some people can take the hormone and feel better but not everyone falls into that category.

    • B12 umm yeah that will kill your energy my mum has b12 anemia it can wreck havoc! Your thyroid is ok why is the fuck are they trying to give you thyroid medication?? We all would love to be the optimal 1 but the ration I believe for normal tsh off meds is .5-4! Get you some b6,b12 folate drops high dose 25oo 2x day and some vitamin D spray to top it off!

  11. I can relate to this article because I dreamed about overcoming my hypothyroidism for years.
    I tried just about everything I could think of but nothing seemed to work.

    Then I did something different and I took back control of my life in a few short weeks. Now I’m happy and don’t think about hypothyroidism anymore.

    If anyone’s interested, here’s a website that helped me a lot:

    Best of luck!