Iodine, the Thyroid, and Radiation Protection

We have friends in Japan, living both north and south of the damaged reactors, and Shou-Ching asked me to do a post about how to protect against radiation.

The Concern

The radioactive substances released by the Chernobyl nuclear power plant meltdown are represented in this chart:

(Source. If you’re wondering what the other radioactive elements are, or why radioactive iodine is a byproduct of uranium fission, a possible place to start is Wikipedia, “Fission products by element” ).

Note first of all that the chart presents percentages of radioactive substances, not amounts. The amounts are highest on the first day and then decline rapidly. The great danger comes in the first few days.

During these dangerous first days, iodine-131 is, along with tellurium-132 and its decay product iodine-132, the dominant source of radioactivity. These radioactive iodine species account for over 50% of the radiation.

Not only its abundance, but also its effectiveness at causing biological damage make iodine far and away the greatest danger. Iodine radiation is highly effective at causing cellular damage:

Due to its mode of beta decay, iodine-131 is notable for causing mutation and death in cells which it penetrates, and other cells up to several millimeters away. [Source: Wikipedia, Iodine-131]

Worse, iodine is an important biological molecule that gets concentrated in the thyroid. So the dose of radiation becomes very high in the thyroid, and this leads to DNA damage producing a high risk for thyroid cancer.

Thyroid cancer is “the only unequivocal radiological effect of the Chernobyl accident on human health.” [1] Since Chernobyl released a great deal more radiation than the Japanese reactor meltdowns are likely to do, it’s likely that this will be the case in Japan also.

The rate of thyroid cancer after Chernobyl was higher the younger the age at time of exposure. Children and infants are at greatest risk:

It is now well documented that children and adolescents exposed to radioiodines from Chernobyl fallout have a sizeable dose-related increase in thyroid cancer, with the risk greatest in those youngest at exposure and with a suggestion that deficiency in stable iodine may increase the risk. [2]

The last point is crucial – iodine deficiency increases the risk.

Iodine deficiency and radiation risk

In iodine deficiency, the thyroid gland has difficulty generating enough thyroid hormone. T4 thyroid hormone, manufactured in the thyroid and so named because it has 4 iodine atoms, is 65.4% iodine by weight, so iodine is the key ingredient in thyroid hormone.

To compensate for an iodine deficiency, the body does two things:

  • The thyroid gland grows, so that it can more aggressively scan the blood for iodine. An enlarged thyroid is called a goiter.
  • The pituitary gland issues thyroid stimulating hormone (TSH), which induces the thyroid to aggressively scavenge iodine from the blood and turn it into thyroid hormone.

So in iodine deficiency the thyroid is aggressively scavenging all available iodine. This means that when a large dose of iodine-131 or iodine-132 arrives during radiation fallout, these radioactive iodine atoms are quickly picked up by the thyroid. There, they release their radiation and damage the thyroid.

On the other hand, in thyroid replete persons, the thyroid has all the iodine it needs and takes up little iodine from the blood. In this case, iodine that enters the body is distributed throughout the body, or excreted. Doses in any single cell are much lower. The danger to the thyroid is not much greater than that to other organs – which, the Chernobyl experience tells us, is not detectable to epidemiology. (There is even a theory that low-level radiation may be beneficial through hormesis.)

How can the thyroid be made replete with iodine?

The best way, which we recommend in our book, is to supplement with iodine and gradually build up the dose over a four to six month period. Start below 1 mg/day, take that for a month, then double the dose. After a month, double the dose again. Continue doubling until you reach your desired maintenance dose; we recommend at least 3 mg/day (a quarter Iodoral tablet), with 12.5 mg/day a reasonable dose. Some people taking as much as 50 mg/day.

At 12.5 mg/day, it can take a year or more to become replete with iodine in all tissues and to fully drive out other halogens, such as bromine, from the body. This has great benefits for immune function. So, it is best to get started!

Risks of high-dose iodine supplementation

If a person’s thyroid gland is adapted for iodine scarcity and the person takes a large dose of (non-radioactive) iodine, the likely course of events is:

1.      Hyperthyroidism. The thyroid, aggressively scavenging for iodine to repair a deficiency of thyroid hormone, scoops up all the iodine and makes a large amount of thyroid hormone. The person develops symptoms of hyperthyroidism (too much thyroid hormone): anxiety, intolerance of heat, muscle aches, hyperactivity, irritability, hypoglycemia, elevated body temperature, palpitations, hair loss, difficulty sleeping.

2.      Wolff-Chaikoff effect. As thyroid hormone levels become too high, the body induces mechanisms for suppressing thyroid hormone production. Simply reducing TSH output is not effective to suppress thyroid hormone production if a very large iodine influx is received. Fortunately there is another mechanism for suppressing thyroid hormone formation, mediated by iodine itself: the formation of iodine-rich proteins (iodopeptides) in the thyroid that inhibt synthesis of the thyroid peroxidase (TPO) enzyme. Normally, this mechanism operates for a few days and wears off, restoring normal thyroid function. [3]

3.      Reactive hypothyroidism? Usually, everything will normally return to normal after a few days. But sometimes in previously iodine-deficient adults and more commonly in newborns and fetuses and some diseased persons, after very high doses of iodine the Wolff-Chaikoff effect can persist. In this case the early hyperthyroidism is followed by a period of hypothyroidism (too little thyroid hormone). This “hypothyroidism is transient and thyroid function returns to normal in 2 to 3 weeks after iodide withdrawal, but transient T4 replacement therapy may be required in some patients.” [3]

4.      Risk for lasting hypothyroidism. People who develop a reactive hypothyroidism following a large dose of iodine are at high risk for later development of persistent hypothyroidism. [3]

So most people will experience transient hyperthyroid symptoms for a few days and then do fine. Some will develop a reactive hypothyroidism lasting a few weeks and then be OK, save for an elevated risk of hypothyroidism later which may or may not be due to the reactive episode.

Advice of the authorities to fallout victims

The advice from public health authorities is a compromise between the protective effects of high-dose iodine and the risk of messing up the thyroid.

A US Center for Disease Control (CDC) fact sheet explains the recommendations. A single large dose of iodine offers protection for about 24 hours. Recommended intakes are:

  • Adults should take 130 mg/day while exposure persists.
  • Children older than 3 and smaller than adults should take 65 mg/day while exposure persists.
  • Infants and toddlers aged 1 month to 3 years should take 32 mg/day.
  • Newborns should take 16 mg/day.

Our advice

The CDC dosage advice strikes us as very reasonable.

If you are not currently exposed to fallout, but think you may be exposed in the near future, you should consider beginning with small doses of iodine now – say, 3 mg/day. If that does not produce any symptoms, then try 6 mg/day; if it does, back off to half that dose. This will begin the adaptation process for your thyroid gland and help minimize hyperthyroid or hypothyroid reactions if you do have to take high doses.

Also, obtain your iodine tablets in advance. If fallout does occur, it may be hard to find iodine pills. says they are out of stock and have a large order backlog. I saw a story the other day that a 14-dose packet of potassium iodide was being sold at one site for $200, up from the normal $10 list price.

We recommend Iodoral 12.5 mg tablets. This is a good size for supplemental use; to reduce it to a 3 mg dose, cut the tablet in quarters with a razor blade. If fallout arrives, you can use ten Iodoral tablets to get a 125 mg adult dose.

For doses below 3 mg, smaller iodine tablets or liquid iodine solutions may be best; you can dilute liquid solutions to your desired dose. Some brands were recommended by readers in comments on our Supplement Recommendations page.


Outside of Japan, the risk is minimal, and even in Japan those who are replete with iodine are unlikely to develop thyroid cancer from exposure. After Chernobyl, thyroid cancer rates were high in Russia, the Ukraine, and Belarus which did not distribute iodine, but low in Poland which did. Fortunately, Japan has one of the highest iodine intakes in the world thanks to its high seaweed consumption. With that preparation plus proactive distribution of iodine tablets, we can expect and hope that the health effects of the reactor meltdowns will be minimal.


[1] Thomas GA et al. Integrating Research on Thyroid Cancer after Chernobyl-The Chernobyl Tissue Bank. Clin Oncol (R Coll Radiol). 2011 Feb 22. [Epub ahead of print]

[2] Cardis E, Hatch M. The Chernobyl Accident-An Epidemiological Perspective. Clin Oncol (R Coll Radiol). 2011 Mar 9. [Epub ahead of print]

[3] Markou K et al. Iodine-Induced hypothyroidism. Thyroid. 2001 May;11(5):501-10.

Leave a comment ?


  1. So, what if I want to obtain my iodine from seaweed? Is that a reasonable proposition or are supplements all but necessary? The seaweed I eat claims to provide 100% RDA in .2oz.

  2. Hi Matt,

    Seaweed is good for small doses. It has a variety of nutrients to go along with the iodine. But seaweed has other halogens including bromine, and toxins such as arsenic.

    Some people have bad reactions to seaweed, as JVN did ( Almost everyone will react to large amounts of seaweed. Inorganic iodine, however, is safe as long as the thyroid is adapted to the dose.

    So I would recommend inorganic iodine over seaweed if you want large doses.

  3. Hi Paul

    I certainly hope it doesn’t become an issue for you or any of your readers, but if it does, and potassium iodide becomes prohibitively expensive or hard to get, I can order KI drops through my practitioner account and ship to the USA if need be. 1 drop = 125ug of iodide. I would need to cover my costs, but I could probably land a 50mL bottle in the USA for $20NZD (~$15USD).

    Just an option if it is required.


  4. Hi Jamie,

    Very kind of you to offer!

    I think Iodoral is readily available in the US, and most pharmacies probably have potassium iodide. Also, I believe that by the time fallout reaches the US the radioactivity doses will be very small. It will have dispersed over such a large area, and decayed in the travel time.

    In Japan, radioactivity can be dangerous, but time is short. Most likely they’ll either get water to the reactors or experience a meltdown in the next 48 hours.

    Let’s cross our fingers and hope the problem is resolved!

    Best, Paul

  5. Hi Paul,

    Thank you for your great post. I am a new reader to your blog and totally enjoy the educational content.

    Out of curiousity, does cooking with iodized table salt (Morton’s) help prevent thyroid hormone deficiencies? Could one replete themselves with ordinary iodized table salt over time?

    Or is there a benefit to using a potassium iodide supplement?

    Thank you for your time.


  6. Hi Paul,

    Just a quick question about the suggested amount of Iodine. After a year or so at a dose of 12.5 mg/day, would one continue at that dose indefinitely or would one taper off and cease taking iodine at that time ?



  7. Hi Erik,

    Iodized table salt will prevent severe deficiencies, of the type that produces cretinism.

    It won’t be enough to optimize iodine status. It is completely useless against radioactive fallout.

    Potassium iodide supplements will enhance immune function and ensure that no iodine deficiency hypothyroidism can occur.

    But be sure to start low and build up slowly.

    Hi Justin,

    Yes, I would continue it indefinitely. The goal is to maintain excellent immune and thyroid function throughout life. We are always threatened by chronic infections, so you want your immune cells to be scavenging pathogens effectively at all times.

    Best, Paul

  8. What about those of us not likely to be exposed to radiation but wanting to make sure our iodine levels are replete. Where do we start and how do we determine what our needs are? Is the average Paleo/PHD diet still deficient and in need of supplementation?

  9. Hi GeeBee,

    Yes, I think everyone should supplement iodine at some level. It’s one of our eight essential supplements.

    Start below 1 mg/day, maybe 0.5 mg/day, for a month. Then double the dose once a month – slower if you have hyperthyroid symptoms. It might take 6 months to work up to 12.5 mg/day which is a good level.

    Note this is not so much relieving deficiency — 0.5 mg/day would do that — as trying to optimize immune function. I think the higher dose has modest but real long-term benefits.

    Best, Paul

  10. Thanks Paul
    I have some Lugol’s solution that I bought a while back but didn’t use. At the time iodine was being discussed extensively in low-carb forums etc. but I just wasn’t sure about the reliability of the ‘talk’ back then. Do you think it would still be safe to use? (would be 2-3 years old now)
    Also from what I can gather, one drop equals 6.25mg. Should I start out with one drop every two days to get the 3mg or dissolve 1 drop in some water and drink half each day?

  11. A few questions: why is the info I read everywhere including here, saying that the only human health effects of Chernobyl were an increase in thyroid cancer? Doesn’t radiation cause many other problems? Since I was a kid ive seen pictures of disfigured children born near the Chernobyl accident and I was told these kids, many whom were born missing limbs and with other deformities, had been in utero at the time chernobyls meltdown happened.

    Also, I read on The healthy skeptic blog that he believes 90% of people who have hypothyroidism disease also have hashimotos thyroidosis and therefore supplementing with iodine can cause an immune response making the disease even worse.

    Your posts are always interesting, carry on!

  12. Hi Paul,

    First, thanks for your book, it’s just great!

    Second, a question about iodine. I’ve started taking Iodoral about 2-3 weeks ago. But as it turns out, I misread/miscalculated the dose and started right from 6 mg (half a tablet) a day. I don’t have any problems with this (and didn’t notice any change, generally speaking). Should I decrease the dose to 3 mg, or do you think 6 mg is OK?

    Thanks again!

  13. Hi GeeBee,

    It’ll still be good.

    I would start much lower than 3 mg/day, unless you think some fallout is headed your way. If you have a larger bottle, try making a 10:1 dilution, then take 1 drop per day. That’ll give you about 0.5-0.6 mg/day which is a good starting dose.

    Hi Emily,

    Radiation can cause other problems including birth defects. But those require higher doses, and happened to people living in the immediate vicinity of the Chernobyl plants.

    In Japan, the immediate area of the plants has been evacuated. We’re looking at fires in spent fuel rods supplying radioactive vapors that then have to travel 20 km or more to find people. The doses will be much lower than in Chernobyl itself, where people had no warning and the explosions were catastrophic.

    So immediate dangers are all from iodine. It’s possible that longer-lived isotopes like cesium and strontium could pose a long-term problem if they get in the food supply (i.e. in milk, eggs). That would require a large radiation release. Hopefully that won’t happen.

    It’s true that 90% of American hypothyroidism is thought to be autoimmune — probably mainly wheat mediated.

    We mention the risk of exacerbating autoimmune thyroid attacks in our book. In the book we recommend giving up wheat and other toxic immunogenic foods 6 months prior to beginning iodine. (Giving up toxins is our Step Two, supplementing is our Step Three.)

    There’s controversy in the hypothyroid community over iodine supplementation for Hashimoto’s. Dr. Brownstein favors it, and so do some of our commenters – e.g. Mario. Dr. Datis Kharrazian opposes it. Look back at some of the early hypothyroidism comment threads for discussion.

    My belief is that eliminating wheat first and then increasing iodine dose slowly is probably still the best strategy for Hashimoto’s. If the iodine is making problems worse, you’ll notice it. I think such cases might be rare if the iodine dose is increased slowly.

    Hope this helps! Do you have hypothyroidism?

    Hi Igor,

    If you didn’t notice any effect then it should be OK. I would stay at 6 mg for a while just to be sure.

    Best, Paul

  14. Sorry, you did make the dosage clear in your previous reply but I misread it. I will make up the 10:1 solution as suggested. Thanks again for the tips!

  15. Excellent post, Paul.

    As you point out, the composition of radioactive elements involved is important. There seems to be a real paucity of information about this at the moment (and plenty of misinformation and hysteria).

    This link (in Japanese) gives hourly readings of airborne iodine and cesium as measured by the Tokyo Metropolitan Industrial Research Center in Setagaya, Tokyo.

    I got it from the comments section of Brave New Climate an excellent source of info, in my opinion, but perhaps too ‘pro-nuclear’ for some.

    I’m not sure (as in literally have no idea) if Chernobyl would be a good model for the proportion of elements of fallout from the current situation, since it was a full meltdown of a more primitive type reactor.

    Anyway, the information about iodine is valuable and informative, thanks.

  16. On a personal note (n=2!), I’m in my second month of supplementing iodine. I started at the 1 mg mark and am now dosing 2 mg daily. I haven’t had any adverse effect that I know of. My wife, who has Hashimoto, and who hasn’t completely given up wheat, is in her first month of supplementing 1 mg every other day (or 0.5 mg daily). She, too, hasn’t had any adverse effects. As a matter of fact, she’s had great improvements in other facets of her daily life (she says it’s the first time she can remember not being constantly hungry, and she’s hasn’t been on a calorie restricted diet), but that might have more to do with other things (supplementing vitamin D and K2, as well as doing most of the PHD recommendations). So, slow and easy seems to work for us.

  17. I don’t have any access to iodine supplements in my country, but I do take some seaweed tablets every day, 2 tablets of Kelp and 4 of Spirulina.

    They seem to be high quality brands so I’m not really worried about contamination.

  18. I am having hashimoto thyroiditis. I am off wheat and multiple other common allergens for quite sometime but I find that iodine makes my condition worse if I take sea fish. My antibody level has come drastically down after I changed to paleo diet (with 50gm Lamb Kidney per day, 1000mg vit C, 20 min sun bath, Vitamin B complex, Vitamin B6 extra, Magnesium, coconut water (2 glass)).
    There is a risk of iodine supplementation: It causes Glutathione peroxide to form which is highly oxidizing; Selenium reacts with Glutathione peroxide making it non-oxidizing. Selenium is very important antioxidant. Our body stores it where there is oxidative stress. It is found in thyroid gland, joints, kidney etc. It is best to improve your selenium stores before going for iodine supplementation.

    It may be ok to supplement 12mg/day of iodine if you want to protect from radioactive radiation but otherwise does it make sense. Are we evolved eating 12.5 mg/day of iodine? In other words — Are we evolved in Japan?

    Proponents of iodine claim that it is very important for brain development. Certainly, but that doesn’t mean the more the better. I mean there are smart people all over the world. People normally living closure to sea are smarter (That is my observation) but is it because of iodine or DHA?

    We tend to get over excited when there is new research and people are all over it. I think moderation is best.

  19. No, I’m not dx as having hypothroid but it does present itself in my immediate family.

  20. Hi Paul,

    Thanks for this post on iodine.

    You mentioned in one of the replies that ‘seaweed has other halogens including bromine, and toxins such as arsenic’, and thus you recommended ‘inorganic iodine over seaweed if you want large doses’.

    Against this background, is it wise to get say 4mg or 6mg (or more maybe more in the future indeed) of iodine from Kelp tablets?


  21. Hi Sean,

    It’s a good point that the mix of decay products may be a bit different from Chernobyl … but these are all uranium reactors, reactor 3 had just a bit of plutonium mixed in its fuel, so I doubt the decay products are much different.

    Hi Poisonguy,

    That’s great! Work on your wife’s wheat addiction, that’s probably the key to Hashimoto’s. Glad she’s feeling better!

    Hi Vizeet,

    I agree, it is best to eliminate grains, let antibody counts come down, and optimize the other micronutrients before increasing iodine doses. Selenium for glutathione peroxidase is as you say very important; so also are zinc, copper, and vitamin C.

    Good advice to keep the selenium in mind. I try to remember to recommend selenium with every iodine/thyroid post, but forgot this time.

    As for evolutionary iodine intakes, in fact we did spend crucial evolutionary periods by the seashore eating iodine-rich foods — shellfish, seaweed, fish — through the crucial middle and late stone age / upper paleolithic. The “Out of Africa” cohort had an especially iodine rich diet.

    Iodine is especially important for humans, having lost the ability to synthesize vitamin C. Vitamin C in land animals developed to compensate for the loss of iodine availability with the move from the sea.

    However, my main argument is not evolutionary, but biological. Iodine has no known toxicity apart from rare allergies to organic iodine compounds and rare autoimmune thyroid reactions, plus the reactive episodes mentioned in the post. It is strongly supportive of immune function, and drives toxins out of the body. There is strong reason to believe that 12 mg/day would be beneficial to nearly everyone, if they got up to that dose without incident. I believe that the few who do have trouble will notice it along the way and be able to deal with it if they start with a low dose and work up slowly.

    Moderation is a good rule. But sometimes, there is a free lunch. Iodine comes pretty close to giving us one.

    Best, Paul

  22. “At 12.5 mg/day, it can take a year or more to become replete with iodine in all tissues and to fully drive out other halogens, such as bromine, from the body.”

    Assuming this stage has been reached, do you recommend that one continue at this dose indefinitely? Or would it be more prudent to taper down to a lower level for maintenance?

  23. Hi Paul,

    Long time lurker, first time posting. I love the book and am making my way through it, tweaking my paleo diet along the way.

    I’ve been on 12.5 mg Iodoral for years with no problems. I have Hashimoto’s and Grave’s! But I also eliminated wheat years ago too.

    My question has to do with pets. Do they need iodine and if so, how much? I have a dog that is 60 lbs and eats a species-specific diet, prey model raw.

    Thank you!


  24. Hi Ulf,

    I wouldn’t get so much from kelp tablets, no.

    In fact now I’m leaning toward not supplementing kelp at all. Eat seaweed, but supplement elemental iodine.

    I will update the Supplement Recommendations page when I get time.

    Hi gh,

    Personally, I would continue. If your thyroid is adapted, there’s no downside to continuing. Cost would be the major issue I guess. That said, there’s nothing wrong with reducing the dose to 3 mg/day. That should be protective. If you were ill you could increase the dose.

  25. Hey does anyone have a source of potassium iodine that I get for a cheap price. I am strapped for money and the Iodoral is to expensive for me to afford.


  26. Hi Teri,

    That’s a great question. They do need iodine, but I don’t know if their needs vary from humans. I might expect it would scale by body weight, so your dog might do well with 1/3 a human dose. I would again start low – you don’t want to induce hypothyroidism!

  27. Hi Paul, I am taking the kelp to work up to being able to take 1/4 of a tablet of the Iodoral. I have hypothyroidism and take 3 grains of Armour Thyroid per day. Is there a better strategy? Thank you!

  28. Hi Kindy,

    Start with grain, soy, and other toxin elimination; keep omega-6 levels down; supplement our 8 essential supplements; start with the iodine around 500 mcg per day; you want to gradually increase it, no more than a doubling per month.

    There will be some fluctuations in thyroid levels as you do this, but hopefully you’ll find you can use less Armour Thyroid.

    Both food toxins and micronutrient deficiencies including copper, iron, selenium, and iodine can cause hypothyroidism. It’s good to get those possibilities out of the way early, since they’re so easily fixed.

    It’s good to monitor thyroid hormone levels along the way. So you might want to visit your doctor periodically. Best TSH levels are below 0.7, but may take some time to get there. Do take your time.

    Best, Paul

    • Hey Paul,

      I am reading some of your older posts. I am on armour and wondering, since my thyroid was radiated, will there be fluctuations in TSH, or is this something specific to people with thyroids.

      I started the 225mcg of iodine and broke out like crazy. My cheeks and forehead were covered, I am 40 years old and dont typically get pimples! I was amazed, and that’s just from bromine?

  29. Hi Robert,

    I just checked prices. There’s no cheap iodine available right now!

    I would wait until the panic is over. The 180-tablet Iodoral we recommend on the supplement recommendations page is normally about $50. If you take 6 mg/day (half tablets) that will last a year; at 3 mg/day (quarter tablets) 2 years. At $25/year/person, that’s not too expensive. Those are reasonable doses.

    Best, Paul

  30. Hi Paul, Sorry if I’m being a bit dense but when you say ‘start with iodine about 500 mcg per day’ – do you mean only potassium iodide or can I get this from Kelp? I am taking 900 mcg of the Kelp per day right now with no side effects that I have noticed.

    I’ve been off grains, soy, etc. for a long time so that should be no problem. I follow the outlines of your diet pretty closely with perhaps a bit too much pork (we live in Denmark). I just had a thyroid test in January and I am due for another in June so that will be a good check point. Thank you, Kindy

  31. Hi Kindy,

    Yes, kelp is OK … They’ll give the iodine dose on the label.

    If you have no effects on 900 mcg iodine, that’s great. If you’ve been on it a month then you can try, say, 1.5 mg. At this point I would try to switch to elemental iodine, which is usually available as potassium iodide salts.

    If 1.5 mg is well tolerated for a month, you might try alternating 3 mg and 1.5 mg for a week, then 3 mg daily if that went OK. You might stay at 3 mg through your June appointment to see where you’re at. Then if all is well head to whatever you decide is the best long-term dose.

    It’s best to drink plenty of water and eat sufficient salt during this period – it helps excrete bromine. Signs of bromine release include acne or other skin disturbances. These will disappear once you are replete with iodine.

    Best, Paul

  32. Some time ago, I showed to Dr. Kharrazian that all the studies he cites about iodine exarcebating Hashimoto were done in countries with selenium deficiences. His only answer, thru his secretary, was that I misinterpreted the studies I cited to prove my point…

  33. Thanks, Mario.

    I believe you’ll be proven right — it’s other nutrient deficiencies, esp selenium, that make iodine dangerous in Hashimoto’s.

    I think the best advice is just to do things in the proper order: (1) eliminate wheat and other goitrogenic and immunogenic toxins; (2) fix all other micronutrient deficiencies with good supplementation; (3) slowly build up iodine. If we’re right then no one will have any trouble. If they’re right, the trouble will be detected early without much damage being done.

    Best, Paul

  34. How much dried seaweed is too much? I realize that it may vary from type to type. I eat a lot (mainly dulse) because it tastes great and I feel better when I eat it (just more energetic, less foggy and lethargic), but I don’t want to wind up in a hypothyroid state. Informed insights from anyone –esp Paul 🙂 — are greatly appreciated… thank you!

  35. Hi Joyful,

    Well, if it makes you feel great eat it!

    Seaweed can soak up environmental toxins, but if you have a good source, it’s a very healthy food.

    I’ve heard of more trouble from taking kelp than from dulse. It might be a safer seaweed.

    Best, Paul

  36. This is very interesting advice on iodine supplementation. Do you have a relatively complete list for the non-wheat members of the family of “goitrogenic and immunogenic toxins?”

  37. Hi Jeremy,

    Wikipedia has a long list of goitrogenic foods: Of these soy is the one I would be most concerned about.

    Gluten is the biggest concern for autoimmunity, so rye and barley along with wheat. But any allergen can heightened autoimmune activity. Most common food allergies:

    These lists cover an awful lot of foods, and I wouldn’t advise avoiding them wholesale. I think the usual prescription – grains, legumes, sugar, vegetable oils – covers the most important bases, and then you should monitor yourself for reactions to dairy protein etc.

    Best, Paul

  38. Thank you, Paul! And thank you so much for your dedication to this work. You sift through the science, share it in a way that’s understandable, and take the time to provide personal responses — it’s all very much appreciated (and thanks to Shou-Ching, too, as I know she’s a part of it all). You both ROCK!

  39. Hi Paul,

    My thanks to you and Shou-Ching for this post. And my best wishes to your friends (and all) in Japan, and any who might be affected by this event.

    Warmly, KKC

  40. Hi Paul,

    My thoughts are with the displaced people of Japan and with the relatives of those lost due to the tsunami.
    We all hope that this disastrous situation doesn’t get worse.
    I was in Romania,in Cluj during the Chernobyl incident and unfortunately we weren’t informed about the fallout, the direction of the wind, the content of cesium or other radioactive material in food. I remember on my birthday on 30th April it was raining and we called it radioactive rain without really knowing what we were saying. It’s hard to find trustworthy information in relation to that period. One study mentions that in May 1996 ‘The Chernobyl 137Cs deposition in Romania has been estimated at Cluj to be 4 kBq.m-2’ I don’t know if it is a lot or not and I don’t remember if we took iodine tablets immediately. In Romania the salt is iodised now, I don’t know about 1986. In Russia they only gave them iodine 4 weeks after the event.
    I understand that the half-life of some of the radioactive elements is very long and they are still found in wild mushrooms, wild animals, sheep, even in UK and Northern Ireland. Some organisations are going to issue some new reports this year with the 25th anniversary, but it’s not likely that the ordinary person is ever going to find out the truth.

  41. Hi simona,

    For dose, a Becquerel is one radioactive decay. A fatal dose of radiation poisoning is 5 sievert, and thyroid cancer rates become appreciable at 0.1 sievert if it’s from iodine. A sievert is on the order of 10 billion cesium decays per gram of body mass. Let’s say 0.1 sievert of cesium is dangerous, for a 10 kg child that’s 10 trillion Becquerel. So 4,000 Becquerel per square meter doesn’t seem like much.

    Basically, the danger is if it collects in food and water, then you eat the food and water. You’d need 2.5 bn square meters worth of farmland to gather one dangerous dose.

    I think the danger was much closer to the reactor, in the former USSR. I doubt Romania had any detectable risk, if the 4 kBq/m^-2 number is accurate.

  42. Thanks for the explanation.
    In Russia/Ukraine they were talking about 155 kBq and the maximum that I saw for our region was 25 kBq/m2. Obviously, everybody consumed the contaminated water, dairy products, eggs, and green vegetables. I’m not trying to overestimate our risk, there isn’t any clear evidence that the population has suffered, I was only saying that we were in the dark.

  43. “Best TSH levels are below 0.7”

    Is that 0.7 mU/L?
    The normal range listed on my test is between 0.4 and 4.0 mU/L. My last test result was 1.81 mU/L and I was told that was fine. So should I be using the near bottom range of 0.7 as my target level?

  44. Hi GeeBee,

    Yes, those are the same units.

    I would expect that as your iodine intake rises your TSH should drop below 1. 0.7 or even lower is a good target.

  45. Hi Paul, I find the whole Iodine equation really confusing. I have your book and love it, and wonder if you could help.I would like to begin supplementing with Iodine,and bought a liquid concentrate by Eidon, Ionic Minerals. 2 drops provides 225mcgs of Potassium Iodide.I’m at the beginning…Can you suggest how I should proceed? Should I dilute it to begin with? If so, can you suggest how, and how I would build up over time.Thank you, Susan

  46. Hi Susan,

    There’s no need to dilute it, 225 mcg is a low dose.

    You might try 2 drops a day for a week. If you don’t notice anything, increase to 4 drops a day. Gradually increase the number of drops until you either you notice an effect or you’re at 1 mg/day. Stay at that dose for a month. From there, assuming symptoms have all disappeared by the end of the month, double the dose no more often than once a month. If symptoms are severe, back off a bit.

    Pick a target dose to maintain – I would suggest 3 mg/day to 12 mg/day for healthy people, but possibly more for therapeutic purposes such as dealing with chronic infections – and stabilize there.

    Also, be sure to supplement selenium along with the iodine.

    Best, Paul

  47. Hi Paul,

    reading your book, thanks so much for sharing your knowledge. I am following your recommendations closely after nearly being 2 years paleo. I understand that supplementing with iodine is not recommended for people with Hashimoto’s. I don’t have hypothyroidism, but my thyroid test results are not optimal either according to my doctor.

    TSH: 2.1 mIU/L (ref. range 0.5-4.5)
    Anti-thyroidal Peroxidase abs: 61 U/ml (ref. range <60)
    Urine iodine spot: 252 nmol/L; 32 ug/L (moderate deficiency)

    Currently taking 700 mcg of iodine per day, starting at 300 mcg three weeks ago and slowly increasing. Feel like this has benefited me, in particular inexplicable night sweats have greatly improved. Planning to increase to 1mg. Would you advise going higher, say to 3mg. Or does this risk worsening my thyroid status.

    Other diagnoses: microscopic colitis (in remission) and psoriasis (v. mild since going gluten free in 1999), joint pain (non-existent since ditching corn in 2004)



  48. Hi David,

    I believe iodine supplementation is beneficial for people with Hashimoto’s 99% of the time, and is very likely to benefit your colitis, psoriasis, and joint pain too.

    For safety, it’s crucial to follow some steps:
    1) Eliminate grains (except rice) and goitrogens (e.g. soy) from the diet. If there’s trouble adding iodine, you may need to wait until 6 months after wheat was eliminated.
    2) Supplement with other thyroid-related minerals first, esp. selenium and copper.
    3) Start with a low dose of iodine – say 500 mcg/day (0.5 mg/day).
    4) Build up the dose slowly, doubling it once a month. E.g., after a month at 500 mcg/day, spend a week alternating 500 mcg and 1 mg per day, then do 1 mg/day for the remainder of the month. The next month, spend a week alternating 1 mg and 2 mg, then the rest of the month at 2 mg/day. Then go to 3.125 mg (a quarter Iodoral tablet) the next month. Then 6.25 (half Iodoral) the following month, and 12.5 mg (one Iodoral) in the 6th month.

    In your case, since you’re at 700 mcg/day, I would try getting up to 1.5 mg next month and then 3.125 mg (the quarter Iodoral tablet) the month after.

    A razor blade is a good tool for cutting the Iodoral tablets.

    I would go to 12.5 mg/day over 6 months and then stay there. I believe if you follow the above steps, you will adapt to higher doses within 3-4 weeks and there are unlikely to be any negative effects.

    After you reach a dose you want to maintain and have been on it more than a month, go back to the doctor and get a thyroid panel to see how it’s changed.

    If you have any severe trouble when raising iodine dose, back off to the previous dose, wait a few weeks, and try again.

    Let me know how it goes.

    Best, Paul

  49. Thank-you Paul, your answer is very much appreciated.

    Kind regards


  50. Hi Paul,

    Newbie here. I work at an acne clinic and the owners and Dr. Fulton (wrote the book on acne) claim that iodine triggers acne. What are your thoughts on this? I just read that “Signs of bromine release include acne or other skin disturbances. These will disappear once you are replete with iodine.” Can you tell me where you found this research?



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