How Iodine Protects Breasts

Iodine material signI wish more women would take iodine. Not for thyroid—but to prevent breast cancer.

Iodine has a long history of being effective treatment for breast symptoms such as pain and cysts. There’s now growing evidence that iodine may also help to prevent breast cancer.

Iodine for immune and breast health

Did you know that 80 percent of the body’s iodine is not in the thyroid gland? Instead, it’s in the immune system, eyes, stomach, salivary glands, brain, ovaries, and breasts. It’s there to stabilize the fatty acids of the cell membrane and protect cells from oxidative damage. Iodine also directly supports immune cells — to the point that immune cells have been known to actively break apart thyroid hormone to harvest the iodine.

In the breasts, iodine down-regulates estrogen-responsive genes and up-regulates the genes required for estrogen detoxification. Having enough iodine can prevent breast tissue from becoming hyper-sensitive to estrogen.

Interestingly, progesterone enhances iodine uptake, which may be one way that progesterone protects against breast cancer.

Researcher Carmen Aceves has recently trialed iodine as an adjuvant therapy for breast cancer.

Safe use of iodine

Be careful with iodine supplementation because iodine overdose can trigger autoimmune thyroid disease and hypothyroidism. Fortunately, that is less likely to occur when there is adequate selenium to stabilize thyroid tissue.

How can you get enough iodine for breasts without injuring the thyroid?

Before I prescribe iodine, I test for thyroid autoimmunity or “thyroid antibodies.” If there is autoimmune thyroid disease, then I stay below 500 mcg (0.5 mg) of iodine or avoid it altogether. If there is not autoimmune thyroid disease, then I typically prescribe between 250 mcg (0.25 mg) and 3000 mcg (3 mg) in the form of either potassium iodide (KI) or molecular iodine (I2). Molecular iodine is safer than potassium iodide because it’s absorbed more slowly into the thyroid and more quickly into breast tissue.

👉🏽 Tip: Breast tenderness can be a sign of iodine deficiency. I personally find it more useful than tesing for urinary iodine.

A high dose of iodine in the range of 30,000 – 50,000 mcg  (30-50 mg) is not safe. Read your supplement label. There is a 1000x difference between mcg and mg.

Please also read: Why I Prescribe Iodine for Breast Pain, Ovarian Cysts, and PMS

76 thoughts on “How Iodine Protects Breasts”

  1. I know this is an older post, but I had questions About whether exposure to excessive iodine has ever raised your clients serum testosterone? Im looking into this because I had extremely high total testosterone ( but regular free testosterone) on bloodwork and have been using an iodine spray 2-3x a day for a sick cow I’m working with (she has a contagious udder disease that causes severe ulcers etc). My hands get covered in this 1% iodine spray 2x a day for 1/2 hour at a time. .. yes I should have been wearing gloves!!! I’m seeing a lot of guys take iodine to raise their testosterone levels, including typically and wondering if 7 weeks of doing this affected my bloodwork. I’m going to stop and be retested but curious if your years of practice you’ve ever seen something re testosterone level and excess iodine. My Dr has no idea if it could.
    Thank you.

  2. You mention that a daily dose of 400 mcg to 1000 mcg is safe for most people, even those with autoimmune thyroid disease (and especially if they co-supplement with selenium).

    I just want to point out that Violet iodine has 3,000 mcg. They even mention in the FAQ ( that you can take an addition pill for more severe symptoms.

  3. Hi Dr. Lara, These are my thyroid hormonelevels : Total T3 – 102 ng/dl, Total T4 – 6.6 mcg/dl, TSH – 3.67 mcIU/ml. I read in your book that this should be considered as hypothyroidism. My Anti TPO Antibody level – 7 IU/ml. So since this is not autoimmune hypothyroidism , what would you suggest as a treatment?

    • May I add that I have painful breasts a week before my periods so I am deficient in Iodine. Would iodine supplementation be the answer to my above concern as well?

  4. I’ve had sore breast for half a year now. Always returning 2 weeks before my period. My breasts get fuller. I also have had a big issue with acne, and I know iodine can aggregate acne. What should I do? I also have symptoms like pre menstrual spotting, water retention (face mostly), headaches, bladder infection, sugar cravings. My vit d and progesterone was a little low at my last bloodtest

  5. I bought your book and for the first month was very meticulous about taking all the supplements. Wouldn’t you know that month I had almost zero PMS issues. This month I got a little lazy… primarily about taking my iodine. Yesterday I woke up with sore breasts and was so confused as to why I was experiencing this symptom a week out from my period. Low and behold… I had been inconsistent with my iodine intake this month. This is proof that what you have outlined in your book and on this website works!!

  6. Hi Laura,

    Great article! I can safely say that I have been taking 2 tablets daily of 400mcg on Sea Kelp from Lifeplan and I no longer suffer from heavy periods! I have increased energy and I have noticed that my hair is looking far healthier too. I have been on these supplements for 2 months and I see the difference. Just make sure the Sea Kelp is from unpolluted waters and you are good to go!

    • Indigo, have you had symptoms of breast tenderness/fullness and has the Kelp alleviated this? Do you also supplement with Selenium and if so, how much? What brand of Kelp?

    • Great question. Breast tissue needs iodine, so Yes, I would say that women with larger breasts need a larger supply of iodine. But I am not aware of any research on this.

      • I would say, due to the fact that iodine does not just got to the breast, but is distributed throughout the whole body, it would beg the question, and in my sense confirm the answer that the amount of iodine depends very much on the size and weight of the woman – a big difference in iodine uptake between a small breasted ‘slip of a woman’ and a large ‘big breasted’ woman!

      • I have experimented with iodine. I do the patch test. My doctor tested my levels and my sweet spot that keeps me mid range seems to be 24mg. Yes I know it’s a lot. Could this be that I have very large breasts and estrogen dominance?

  7. Thank you, Lara. The advice in all of your articles is so clear an easy to follow.

    I have had sore, lumpy breasts during the entire second half of my cycle for the past year and a half. This may have been an issue for much longer, but I was either pregnant or breastfeeding (or both) for the previous 5 years, so it was difficult to tell.

    Prior to that, I had never had sore breasts. Even during my first pregnancy, my breasts were not a tiny bit sore.

    So, this would indicate that I probably have an iodine deficiency. I’ve been hesitant to take iodine, because I am trying to clear my acne, and have heard that iodine can aggravate acne.

    What I have noticed is that since cutting out milk 3 months ago, my breast pain has just about disappeared. Last month, I cheated and had milk and cheese and the pain came back.

    Do you think my breast pain is caused by inflammation from the milk, or do I still probably have a need for extra iodine?

    • Sounds like dairy inflammation was the main factor. You may not need iodine but you should use iodised salt and eat iodine rich foods.

      • Thank you for your reply. Of course, the day after I posted this my breasts became sore. But, it’s much later in my cycle than normal, and it’s not as bad. I think I’ll give it a few more months of being dairy free, and see if some soreness persists or if it completely goes away.

        Thank you so much for the practical advice you have on this website. I’ve had acne for over 20 years, and had tried brief periods of going dairy free, but, until now, never stuck it out. There is so much other advice on how to treat acne holistically on the web that it gets overwhelming. I appreciate that you outlined just the major things that have been shown to help. Learning about how dairy affects periods was also important for me. I noticed a big difference in my period the first month I went dairy free – and had a horrible period the next month when I cheated and had lots of cheese. This is enough motivation to stay dairy free, even if my acne doesn’t clear up.

        How likely is it that iodine will cause breakouts in people prone to acne?

  8. I found your site yesterday when I was looking for explanations about Vitex. At the same time that I loved all of your posts that I could read until now, I regret not being in Australia so that I could see you. The way you explain everything helps us to understand lots of things. However, things look so complex that I’m afraid of take the medicines – even knowing they are naturals – by myself. Sadly, until now I’ve never find a doctor that could pay attention at me as a whole. For sure I have hypothyroidism (hashimoto origin), insulin-resistence, and I feel strong breast pain every menstrual cycle. Doctors have not agree at all about the possibility of having PCOS (does not appear in ultrasound). Well, thank you for your posts! I’ll keep reading them! I am just wondering if you know some doctor in France or in Brazil that are used to treat pacients just like you… ?

  9. The information on your site is very interesting and helpful. I am disappointed that you do not provide links to back your statement that high doses of iodine are harmful. I am aware of studies that indicate this but there is also question on how well done they are since they use only the TSH as a guide and do not include the importance of selenium. Some people require the high doses to bring alignment back to their systems. Others may not. It would be great to provide comprehensive information on both.

  10. I take a few drops of bioceuticals iodine and a few of selenium in the same cup of water – is that ok?
    I have have hashi but also have lumpy and sore breasts that assume iodine will help with

    • it’s fine to combine iodine and selenium. A few drops of Bioceuticals iodine is about 600 mcg, which should be okay for Hashimoto’s, but you don’t want to go much higher than that without monitoring your thyroid antibodies. Because iodine can stimulate antibodies and worsen Hashimoto’s.

  11. o grande medico dr lair ribeiro recomenda lugol a 5% 2 gts por dia e ele diz que faz bem para a tireoide eu acredito nele.

  12. Hi Lara,
    Would you recommend that people who are planning to start taking iodine also take a selenium supplement, as this is often deficient in soils that our food is grown in?

    • Either potassium iodide or molecular iodine (I2) are fine, but the important thing is the dose. Don’t take too much.

  13. Hi Lara, regarding iodine supplements, I’m post breast cancer, and peri-menopause, apart from Lugols 6.25mgs 5% I think it is (which you say is too strong), what’s the name of an iodine supplement you suggest, and where can it be obtained. Or, could I take 1 Lugols tablet per week. Many thanks,

    • Hi Sally Jane, yes, you could safely take 1 drop per week, which is 6250 mcg per week, or 892 mcg per day. If you don’t have a thyroid condition, you can probably go a little higher (as part of a breast cancer prevention plan), but best to speak to your doctor.

      • Thanks kindly Lara, I really appreciate your response. I have no thyroid issues at all. I’m a ‘less is more gal’ when it comes to taking anything, so with Iodoral which is potassium iodide 5mg of Iodine per tablet, if I took one, maybe two per week, are you saying that would be fine as a protective measure? Thanks Lara – look forward to your response, and Merry Christmas!

        • are you sure it’s a 5 mg tablet? I think ioderal is 50 mg, which is 50,000 mcg. That is simply too much iodine to take in one dose.

          • Hi Lara, Iodoral is 12.5mgs total per tablet.

            Made up of: 5mgs of Iodine, and 7.5mgs of iodine as potassium salt.

            Its a common and supposedly safe brand many use now as either drops or tablets. Many choose the Iodoral tablets as easier for some to digest and there is no taste. Hence one a week, and I would take a break every few months. Much literature about now re Iodine and breast cancer, – as well as Iodine and radioactivity prevention – Fukushima for e.g which US is susceptible to. Iodoral seems to be spoken of more than most. Hence my question to you. I am writing from the US – so perhaps different in Australia.

          • It’s the same in US and Aus. That’s 12,500 mcg iodine, which I think is too much for long term daily dose, because it can suppress thyroid function. The bottom line is that the breasts probably don’t need that much anyway. A much lower dose of 400 mcg is enough to relieve breast symptoms such as breast pain and cysts, so it seems logical to me that it is protective for cancer as well. There’s a sweet spot for dose, and hopefully future research will tell us what that is. For breast cancer prevention, I suspect that it’s somewhere between 500 mcg to 5000 mcg per day.

  14. Hi

    Just wondering if supplementing with iodine for lumpy breast pre period, can the iodine cause weight gain at all.. I have been reading certain article saying it can initially due to the detoxification process.. what are your thoughts on this ??


    • Thanks Kim. Interesting question. I’ve never seen iodine cause weight gain, but I’ve recently had this same question from patients, so it must be out there on the web. My guess would be that high dose iodine (eg. 6 mg or 6000 mcg) is enough to suppress thyroid in some people, and causes weight gain that way.

  15. I note that you mention here that iodine should not be used in the treatment of hashimoto’s. I have read a differing opinion to this from a practioner that says

    “General consensus is that iodine is dangerous for hashimotos. However, this is because they do not understand the mechanism and they (doctors) get themselves into trouble by giving small doses of iodine which does increase antibodies. It is the larger doses that will create the iodolactones that will enable the halting of the antibodies. This is described in the Guide to Supplementing (files of group) and also in Dr Brownstein’s iodine book”

    Are you familiar with this field of thought. I have read of a number of people with hashi’s have great success with using iodine in high doses (with appropriate companion nutrients).

    • Thanks Chris. I am aware of Dr Brownstein’s writings. I cannot comment on his theory that very high doses are safe (when lower doses are unsafe). I am reluctant to just ‘try’ that on patients in case he is wrong. I have personally seen patients flare up their autoimmune thyroid disease with iodine, so I am cautious.

      • Thanks for your reply. I did some further reading on it and apparently it is very important for people with hashimoto’s to not have a selenium deficiency before supplementing with iodine and the doctor’s that are using lugol’s iodine to treat hashimoto’s are first giving them 200mcg -400mcg of selenium (L-selenomethionine) for 2-4 weeks first before starting any iodine and then starting them on large doses…I think it was 50mg (sometimes more) as a daily dose and continuing to include selenium, magnesium, vit c and real salt plus the B2 and B3. There were a number of women on the yahoo iodine group who had great success healing their hashimoto’s and getting their thyroid anti-bodies down…sometimes these antibodies were dropping just with the selenium supplementation. Anyway I think it’s all very interesting and I understand how hard it must be for any practitioner with one as this iodine information is still developing.

        But I’m so pleased to see you mentioning the connection with breast health too. I myself have been taking 12.5mg lugol’s iodine (with selenium 200mcg and other companion nutrients) for more than three years now and during a pregnancy too. I’m not hashi’s though, I’m regular hypothyroid. I have had very good results with it. However I wish I had known about it before I became hypothyroid and before I started using desiccated thyroid supplements because I often wonder if I could have avoided the whole hypothyroid state and having to use desiccated thyroid had I known to supplement with iodine in the first place. there is a book called the iodine crisis by lynne farrow that looks interesting …I haven’t read it yet but plan to soon.

  16. Dear Lara, my thyroid is a bit low and i think i should take Iodine cause i am shedding like crazy for almost a year and i suspect it to the thyroid gland , what level of iodine shoud i take ?

    • Hi Fatima, iodine is not the best treatment for thyroid disease, especially if it is autoimmune thyroid disease (as most cases are). The best treatment is immune-modulation with diet and supplements like selenium. I will write try to write a future post about autoimmune thyroid disease.

  17. Hi Lara,

    Just wondering if you would recommend this a treatment for fibroocystic breast, if so can it be as beneficial if ingested from natural source like seaweed vegetables ie : dulse ??



    • Yes, iodine is effective treatment for FBD fibrocystic breast disease. Effective dose is 0.5-1mg (500-1000mcg). Use caution if you have thyroid disease, as discussed in the blog post. Sea vegetables are ok, but molecular iodine supplement probably better.

  18. Hi Lara, great article and very informative! I have a question regarding breast pain/breast lumps and iodine.
    Can someone displaying no hypothyroid symptoms or any other thyroid issues still be deficient in iodine in their breast tissue?

    • Absolutely. The breast’s requirement for iodine has nothing to do with thyroid. The thyroid can chug along even when the other body tissues are depleted of the mineral. Iodine is much, much bigger than just thyroid.

      • Many thanks Lara. Would you then recommend testing iodine levels before dosing? I am asking because I am a final year Naturopathy student and in student clinic.
        i had a client presenting with sore, lumpy breasts and suggested to my supervisor the client be tested for levels of iodine since i suspected iodine deficiency. I was told I did not need to test because if the client were to have hypothyroid symptoms then that would confirm a deficiency. However, the client did not exhibit hypothyroid symptoms so hence my original question. I’m not sure if this is the right forum for my enquiry but just thought I’d ask : )

        • I do not routinely order urinary iodine, because it is not very accurate.
          Her breast symptoms say that she needs iodine. It’s that simple. It does not matter that her thyroid is normal. The only test that I might consider is thyroid antibodies. If she has a high level of thyroid antibodies (dormant Hashimoto’s), then you must be careful with the iodine dose, and stay below 500mcg (0.5mg). If she is negative for antibodies, then it is safe to give up to 1000mcg iodine (1mg). If you do not want to test antibodies, then just give 500mcg iodine.

  19. Hi Lara
    I am hyperthyroid. Most articles write about hypothyroid which is more common. I would like to make an appointment to see you but I need to know whether you treat hyperthyroid or prefer to deal with hypothyroid.

    I have never been on medication because my T3 and T4 readings are normal but the TSH is usually below the minimum level, however, the last blood test a few weeks ago showed my TSH level as 0.54. Considering the minimum level is 0.5 I really just scrapped in. I’m rapidly losing weight and feel stressed but the Dr doesn’t think this needs checking.

    • Hi Mary, yes, I treat hyperthyroidism as well as hypothyroidism. You can book into my Sydney rooms by contacting my assistant Lisa on Australian phone: 02 8011 1994.

      I will say here that – in many cases- the correct natural treatment for hyperthyroidism is remarkably similar to the treatment for hypothyroidism. That is true when the hyperthyroidism is due to autoimmune thyroid disease (like Hashimoto’s and Graves disease). In that case, the correct natural treatment is to modulate the immune system, and to reduce the autoimmunity so that the thyroid can function normally again. (There are other – non-autoimmune- causes of hyperthyroidism as well, in which case a different treatment would be required.)

    • It’s totally fine to combine iodine with oroxine. The main caution is for those with autoimmune thyroid disease (as discussed in the post).

      Another consideration is that – if the body needs iodine – it may be harvesting it from your thyroxine thyroid supplement. In other words, it is currently breaking down your thyroid medication to take the iodine it needs. Therefore if you take iodine, your body will stop harvesting the thyroxine, and this may mean that you need less thyroxine over time. (but it’s a gradual effect that can be picked up on your 3 monthly blood test).

  20. Dear Laura….
    I have mild hashimotos and have been treating it with Low Dose Naltrexone for several years now. I am wondering the what the best iodine would be. I have been taking 600 mg of organic kelp daily and was wondering if that was too much or if there were something better? Thanks…Hollis

    • Iodine is not a treatment for Hashimoto’s. The best natural treatment for the autoimmune condition is immune modulation with gluten-free, selenium etc (I discuss some of this in my thyroid nodule article). The conventional advice is that Hashimoto’s patients should strictly avoid iodine, but as I explain above, it is not necessary to entirely avoid it because the body needs iodine for other things. I find that patients with very high thyroid antibodies are more likely to react badly to iodine, so then need to stay at low dose: 200-500mcg.

      And as for kelp, I cannot say how much iodine is in 600mg kelp, because the actual iodine content varies from kelp to kelp. Look on the label. Somewhere it should say actual mcg iodine. (again, note the huge difference between mcg and mg)

    • Lugol’s is too high dose. 1 drop provides 6250mcg iodine (6.25mg) as a mixture of molecular iodine and potassium iodide. That is too much for those at risk of thyroid disease. It might be ok if taken one drop per week (works out to 890mcg per day)

      • I’m piggybacking off the Lugol’s solution potassium iodine. I don’t know that I’m at risk for thyroid disease but I would like to add iodine to my vitamins. I do take the selenium you recommended in your book but what is the best for form of iodine? liquid (do you mix with water?) or a pill? The one bad thing about the Lugol’s solution is there isn’t a measurement for this supplement showing what the mcg is per drop (at least not on my bottle!)
        Thank you

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