The most important thing you may not know about hypothyroidism

hypothyroid patientAn estimated 20 million Americans have some form of thyroid disease. Up to 60 percent of these people are unaware of their condition. One in eight women will develop a thyroid disorder during her lifetime. Levothyroxine, a synthetic form of thyroid hormone, is the 4th highest selling drug in the U.S. 13 of the top 50 selling drugs are either directly or indirectly related to hypothyroidism. The number of people suffering from thyroid disorders continues to rise each year.

Hypothyroidism is one of the most common thyroid disorders. One recent analysis suggested up to 10% of women over 60 have clinical or subclinical hypothyroidism. It is characterized by mental slowing, depression, dementia, weight gain, constipation, dry skin, hair loss, cold intolerance, hoarse voice, irregular menstruation, infertility, muscle stiffness and pain, and a wide range of other not-so-fun symptoms.

Every cell in the body has receptors for thyroid hormone. These hormones are responsible for the most basic aspects of body function, impacting all major systems of the body.

Thyroid hormone directly acts on the brain, the G.I. tract, the cardiovascular system, bone metabolism, red blood cell metabolism, gall bladder and liver function, steroid hormone production, glucose metabolism, lipid and cholesterol metabolism, protein metabolism and body temperature regulation. For starters.

You can think of the thyroid as the central gear in a sophisticated engine. If that gear breaks, the entire engine goes down with it.

That’s why people with hypothyroidism experience everything from weight gain and depression to infertility, bone fractures and hair loss.

One of the biggest challenges facing those with hypothyroidism is that the standard of care for thyroid disorders in both conventional and alternative medicine is hopelessly inadequate.

The dream of patients with thyroid disorders and the practitioners who treat them is to find that single substance that will magically reverse the course of the disease. For doctors, this is either synthetic or bio-identical thyroid hormone. For the alternative types, this is iodine.

Unfortunately, in the vast majority of cases neither approach is effective. Patients may get relief for a short period of time, but inevitably symptoms return or the disease progresses.

So what’s the problem? Why have replacement hormones and supplemental iodine been such dismal failures?

Because hypothyroidism is caused by an autoimmune disease.

Studies show that 90% of people with hypothyroidism are producing antibodies to thyroid tissue. This causes the immune system to attack and destroy the thyroid, which over time causes a decline in thyroid hormone levels.

This autoimmune form of hypothyroidism is called Hashimoto’s disease. Hashimoto’s is the most common autoimmune disorder in the U.S., affecting between 7-8% of the population. While not all people with Hashimoto’s have hypothyroid symptoms, thyroid antibodies have been found to be a marker for future thyroid disease.

Most doctors know hypothyroidism is an autoimmune disease. But most patients don’t. The reason doctors don’t tell their patients is simple: it doesn’t affect their treatment plan.

Conventional medicine doesn’t have effective treatments for autoimmune disease. They use steroids and other medications to suppress the immune system in certain conditions with more potentially damaging effects, such as multiple sclerosis, rheumatoid arthritis and Crohn’s disease.

But in the case of Hashimoto’s, the consequences – i.e. side effects and complications – of using immunosuppressive drugs are believed to outweigh the potential benefits. (Thanks to conventional medicine for a relative moment of sanity here.)

So the standard of care for a Hashimoto’s patient is to simply wait until the immune system has destroyed enough thyroid tissue to classify them as hypothyroid, and then give them thyroid hormone replacement. If they start to exhibit other symptoms commonly associated with their condition, like depression or insulin resistance, they’ll get additional drugs for those problems.

The obvious shortcoming of this approach is that it doesn’t address the underlying cause of the problem, which is the immune system attacking the thyroid gland. And if the underlying cause isn’t addressed, the treatment isn’t going to work very well – or for very long.

If you’re in a leaky rowboat, bailing water will only get you so far. If you want to stop the boat from sinking, you’ve got to plug the leaks.

Extending this metaphor to Hashimoto’s disease, thyroid hormones are like bailing water. They may be a necessary part of the treatment. But unless the immune dysregulation is addressed (plugging the leaks), whoever is in that boat will be fighting a losing battle to keep it from sinking.

What the vast majority of hypothyroidism patients need to understand is that they don’t have a problem with their thyroid, they have a problem with their immune system attacking the thyroid. This is crucial to understand, because when the immune system is out of control, it’s not only the thyroid that will be affected.

Hashimoto’s often manifests as a “polyendocrine autoimmune pattern”. This means that in addition to having antibodies to thyroid tissue, it’s not uncommon for Hashimoto’s patients to have antibodies to other tissues or enzymes as well. The most common are transglutaminase (Celiac disease), the cerebellum (neurological disorders), intrinsic factor (pernicious anemia), glutamic acid decarboxylase (anxiety/panic attacks and late onset type 1 diabetes).

In the next post we’ll look more closely at why Hashimoto’s can’t be treated successfully without addressing the autoimmune component, and why both the conventional and alternative approaches to treating hypothyroidism are destined to fail from the start.

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  1. Rosemary’s avatar

    I have been looking forward to your info on hypothyroid and autoimmunity. Great post.
    I am particularly interested in what you have to say on follow-up pertaining to the dessicated porcine replacement therapies (Armour and NatureThroid in the US and THYROID in Canada.)
    I am also interested in having you speak about diet and hypothyroidism. SO much confusing info out there on this. I have read in various places that soy and certain vegetables in their raw form are “goitrogenic” suppressing thyroid function, such as bok choy, broc­coli, brus­sel sprouts, cab­bage, cau­li­flo­wer, gar­den kress, kale, kohl­rabi, mus­tard, mus­tard greens, radishes, ruta­ba­gas, soy, soy milk, soy­bean oil, soy lecithin, soy anything, tem­peh, tofu and turnips. And mildly so, bam­boo shoots, millet, peaches, pea­nuts, pears, pine nuts, radishes, spi­nach, straw­be­rries and sweet potatoes.
    Thanks Chris!

  2. Nancy M.’s avatar

    Most goitrogens are reduced quite a lot by cooking. Eating a ton of raw goitrogenic veggies isn’t a good idea, but having some cooked is not so bad, IMHO.

  3. Chris Kresser’s avatar


    I will indeed cover those topics. It may take a while to get to them, with my licensing exam coming up, but I will at some point.

    I can tell you this briefly: the effects of dietary goitrogens are negligible. I don’t advise hypothyroid patients to stop eating the foods you listed for that reason.

  4. Chris Kresser’s avatar

    I agree. See my reply to Rosemary below.

  5. Rosemary’s avatar

    Thanks Chris!
    Looking forward to more info and good luck on your exams.

  6. barbara lochner’s avatar

    This is all well and good for people who have Hashi & antibodies…But you glossed right over those of us who are plain-old, straight-out hypothyroid.  No Hashi, no antibodies.

  7. Chris Kresser’s avatar

    The focus of the article is Hashimoto’s and the 9 out of 10 hypothyroid patients that have it. Have you had multiple antibody tests? A single negative result isn’t sufficient. The immune system can be so depressed that antibodies aren’t being produced. Patients with hypothyroid need to be tested at least twice for antibodies to rule out Hashimoto’s.

    That said, I will be covering some hypothyroid patterns such as under-conversion of T4 to T3 and decreases/increases in thyroid binding proteins that are relevant to people without Hashimoto’s.

  8. barbara lochner’s avatar

    Yes, I have been tested multiple times with no indication of antibodies.
    Further.  I have been on 4.5 mg LDN (low dose naltrexone) since May, 09.  If you are not aware, LDN modulates the immune system and has positive effects on Hashi for the obvious reason that it is autoimmune.  In my case, during this time my Armour 60 was increased to Armour 75 (compounded).  In my opinion, I should move up to Armour 90 as I have almost no eyebrows, eyelashes, body hair, etc.  My doctor disagrees as he thinks my numbers for TSH, T3 & T4 are perfect.  So far, he’s winning.
    Apparently I’m in a small and lonely group but will look forward to your article re non-Hashi hypothyroidism.

  9. grace’s avatar

    What a fantastic post!!

    Thyroid is so complex. Adrenal issues, omega-3, omega-6, vitamin D, estrogen, etc appear to all play in as well. I look foward to your thoughts!!  I agree that none of the testing for auto-antibodies nail the problem. We can have auto-antibodies to ANY of the deiodinases, lack a mineral or vitamin B for conversion T4 to T3, or thyroid receptors are can be blocked. Also, I’ve been very curious about the role of rT3. So many things are appear to put humans into ‘hibernation’ where rT3 is formed and all metabolism slows…

  10. Sherry’s avatar

    I have a question. I was diagnosed with Hypothyroidism in 1997 and have been on Synthroid since then.  My doses started at 75mcg then escalated to 100, 125, and here in the last 6 months I have gone from a steady 200mcg  to 212 mcg and just recently 250mcg.  I am concerned as to why the sudden increase in my dosage.  I know that the levels must require this, but why?  Just wondered if you could advise. Thanks,

  11. Mario’s avatar

    While I would agree that iodine is not a alone solution, it’s far from inefective. Here, in Brazil, all water have chlorine and fluor. Greenpeace have analyzed the dust on houses here and, like USA, there is too much contaminants, bromine among others. A high iodine dose have been proved to help us to excrete this endocrine disruptors.
    But, it’s not a solution per si. I, for one, have been eating a lacto-paleo diet, extracted all my mercury filled amalgams, take 50mg of Lugols, 100ug of selenium, 4000 UI of vitamin D3 when I can’t get it from sun and take 4.5mg of this FANTASTIC medicine: LDN (
    My antibodies are getting lower and lower every time I measure it. The only time it rised was right after I extracted my amalgams. Rised for 3 months and then started again to lower.

  12. Chris Kresser’s avatar


    Iodine may be a solution for people who have hypothyroidism caused by iodine deficiency, but it will make things worse for Hashimoto’s patients. Why? Because iodine upregulates TPO, which is the enzyme that Hashimoto’s patients are producing antibodies to. This means that iodine will increase the autoimmune attack of the thyroid in these people.

    Population-based studies demonstrate that as iodine intake increases, the incidence of autoimmune thyroid disease increases commensurately. This is a little known fact in the alternative medicine community.

  13. Chris Kresser’s avatar


    I’m sorry, I can’t answer specific questions about individual cases. Thyroid physiology is complex. I would have to do a thorough intake and evaluation to know why you are needing that kind of increase. One possibility, as I discussed in this article, is that you have Hashimoto’s and your immune system is increasingly attacking your thyroid. This would cause a worsening of your disease in spite of increased doses of thyroid hormone. I’ll be covering this in the next article.

  14. Mario’s avatar

    Iodine will not make things worse for Hashimoto’s pacients. Dr. Abraham has debunked this myth (
    I have Hashimoto’s (diagnosed subclinical last year), take high doses of iodine and my TPO antibodies are getting lower day after day.

  15. Chris Kresser’s avatar

    It’s not a myth.  If you understand the physiology of autoimmune thyroiditis, it’s clear why iodine would cause problems.  I will be writing an article on this soon.

    The weight of evidence supports this, Mario.  It’s all over the scientific literature.  I’ll be providing references to these studies in the article.

    Antibody levels are not indicative of the progress of the disease.  For example, low antibody levels may indicate that the immune system is so compromised that it can no longer produce antibodies.  Conversely, there are cases where a patient’s symptoms improve while their antibodies increase (as their immune system gets stronger).

    Basic immunology also tells us that antibodies are not an indicator of tissue destruction. They simply tell the immune system which antigens or tissues to attack.  They don’t do the attacking.  That’s the job of the T-cells.  So high antibody levels don’t necessarily mean more tissue destruction, and low antibody levels don’t necessarily mean less tissue destruction.

    There are so many myths out there about autoimmune thyroid disease.  These are just two of them.

  16. Mario’s avatar

    I do not agree that there is much evidence of this. Lugol was used in large doses in the past and Hashimotos were not higher prevalent than it is nowadays.
    I do not have a compromised immune system. Other than Hashimoto, I never get sick. I do not even remenber the year I got my last flu.
    And my T-cells are normal. They rised right after I extracted my amalgams, but now are lower than they were when I was diagnosed with subclinical Hashimoto and started with Lugol.
    And, also, I don’t have any Hashi symptoms.

  17. Chris Kresser’s avatar

    Regardless of whether you agree or not, there is a large amount of evidence supporting the connection between increasing iodine intake and autoimmune thyroid disease.  I will present it in a future article.

    We cannot draw conclusions based on the experience of one person.  Human physiology is far too complex for that.

  18. Vicki’s avatar

    Hi Chris!  I love reading your blog.  I am hoping that in this series you will also address Graves’ Disease.  Good luck on your exam.

  19. hans keer’s avatar

    Can’t wait until the next post. What is going to be the answer? Maybe thyroid hormone replacement agents such as levothyroxine or desicated thyroid extract? No, surely not. Does it have something to do with soy or grains? Give us the answer soon. VBR Hans

  20. Chris Kresser’s avatar

    Some of what I write will be relevant to GD, because it is also an autoimmune thyroid condition. But I’m not planning to address it specifically. Just not enough hours in the day. Check out Elaine Moore’s book and website on Graves.

  21. Vicki’s avatar

    Thanks, Chris!

  22. Tiffany S.’s avatar

    As someone with Hashi’s and excess reverse T3, I’m looking forward to your next article. Good luck with your exams!

  23. jamie’s avatar

    Interesting article. There is so much about the body that we do not fully understand. However, I do know, that iodine HAS and DOES continue to help people who are hypothyroid, and even hyperthyroid. I do not believe it is THE only and final answer. I believe that one form of supplement containing iodine is not one-size-fits-all. For instance, my body does best with a liquid Dulse supplement, and others with Kelp, and others benefit from Black Walnut, or something like Atomidine or Lugol’s solution. My thyroid was hyperactive, and taking liquid iodine along with magnesium brought it back to normal. I know a woman who cured her hypothyroid, that she had for more than decade, with iodine. One cannot simply say “Iodine makes autoimmune thyroid patients worse” because maybe for a few, it would cure them. Probably for some people with thyroid issues, iodine will not help them at all, but removing whatever is in their environment that could be toxic to their thyroid will.  Every person is different. Of course, treating the thyroid must involve treating the whole body and lifestyle because everything in the body is connected. I also believe strongly in the Blood Type Diet now, although I was a skeptic of that at first. Type O blood type are more disposed to having autoimmune thyroid disorders and for being hypothyroid. Things are NOT ONE-SIZE-FITS-ALL.

  24. Chris Kresser’s avatar

    Iodine will help patients with iodine deficiency, but will generally harm those with autoimmune thyroid disease (AITD). I will explain this in further detail in future articles.

    I can’t agree with you on the blood type diet. There’s absolutely no research to support it, and the explanation he offers is based on completely inaccurate information. The most glaring example is that d’Adamo claims type O was the first human blood type, but phylogenetic networks of human and non-human ABO alleles show that the A gene was the first to evolve. You can read more criticism of the blood-type diet all over the Internet.

  25. jamie’s avatar

    Yes, yes there a lot of d’Adamo haters. I did not believe in it AT ALL at first. However have you actually read his book? Such as “Eat Right For Your Type Complete Blood Type Enclyopedia” ? Have you tried the blood type diet yourself? Do I believe that the blood type diet is the right thing for everyone on the planet? No. But I do believe it would help most people. It is not true that there is ”absolutely no research to support it.” You can read more about how the blood type diet has helped people all over the Internet.

  26. Chris Kresser’s avatar

    I have read the books and tried it myself.  It was one of the first “special diets” I tried. The fact that it has helped some people doesn’t mean anything on its own.  If they’re switching to his diet from the SAD, for example, we can’t know whether it was his blood-type diet that helped or whether it was simply eliminating junk foods.

    Please show me the research that supports it.  There is only research that supports his classification of foods into different categories, but nothing that supports the idea that people with different blood types actually require a different diet.

    From an evolutionary perspective, it makes far more sense that humans evolved to eat a particular diet.  This diet is the one humans ate for hundreds of thousands of years prior to the advent of agriculture and modern food processing.

  27. jamie’s avatar

    How long did you try eating for your blood type? Have you really read the specific book I mentioned?
    I am not Peter D’Adamo. I do not pretend to know everything there is about this diet and how or why it works, nor do I agree with absolutely everything he says. But I believe there IS something to his theories. I myself was astounded by the research in this book. The parallels between blood type, food and disease were impossible for me to ignore.
    Thank you very much for your responses and for this wonderful blog.

  28. Catherine’s avatar

    I was diagnosed with an underperforming thyroid when I was 12 and was never treated. I have now a thyroid that is the size of a 7 year old child. I complained about digestive issues, weak immune system and depression and lethargy. I am taking levothyroxine and have never felt better. Now if this shortens my life so be it but I fell alive .
    I would like to add that I had a grandmother that suffered from hypothyroidism, she had a goiter, she was menopaused before the age of 40 and lived unmedicated a couple month short of 100 years old. She didn’t suffer from dementia and was physically able. I don’t care to live as long and she actually didn’t either.
    So I deducted from that that hypothyroidism doesn’t kill you but makes your life miserable.
    I am skeptical about the thyroxine but I know it made a difference for me.

  29. Chris Kresser’s avatar

    No reason to be skeptical about thyroxine. It can be an essential part of successfully treating hypothyroidism. However, if the underlying immune imbalance isn’t addressed, thyroxine won’t be enough for most people. Or it will be for a short time, but it will stop working and the dose will need to be raised. See the other comments for examples of what I mean.

  30. Elizabeth’s avatar

    I’m 80 years old. Unfortunately, I’ve had hypothyroidism since early twenties, so I’ve taken the artificial hormone, Synthroid, for so long that it’s the only thing I can count on. I can’t fight the disease by better health alone, which is where the author of this series is going to take it. But, it is a good thing to know for young people, so they don’t ruin their health with an autoimmune disease. This is especially true if it runs in families, such as mine. It can take different forms.

    My great grandmother was hyperthyroid with a large goiter. I wish I had her energy without the other hyperthyroid symptoms.

  31. Elizabeth’s avatar

    I wish I had read through the other comments here because blood type was discussed. I’m type B, so no correlation there.

  32. Elizabeth’s avatar

    I would also like to know how Acetyl L-Carnitine effects the thyroid hormones, if you know, Chris. I read something about it. I was taking that and started feeling fatigued, so stopped, and not fatigued now. I was using it to improve my aging mental abilities.

  33. Eva’s avatar

    If I remember correctly, for the blood type diet, types O, A, and B (which is almost everybody), wheat should be cut out of the diet.  If a lot of people cut out wheat, it would not surprise me if a lot of them felt better.  Most people do better without wheat, regardless of blood type. 

    As a type A blood type, I am supposed to avoid meat and tomatoes because my supposed ‘weak stomach’ can’t handle them, but in reality, I feel weak and suffer from anemia if I don’t eat lots of meat.  In fact, I can eat tons of meat with zero digestion probs. I can also eat hoards of tomatoes all at once with zero ill effects.  The only thing I can’t digest is corn, although it does not make me sick, just simply does not digest at all (comes out in the EXACT same form as came in which is kinda creepy!)   The blood type diet totally does not apply to me.  Ironically, my physiology works well with what they say type Os should eat.  I would not be surprised if many of the type Os who ate the type O diet did well on the diet by avoiding all those grains.  But I suspect that other blood types would also do much better if they ate like a type O.

  34. Musings of a Housewife’s avatar

    This is great, now hurry up with the follow-up articles, ‘k?  ;-)  No, really, I am dying to hear what you have to say.  I recently went off synthroid b/c I didn’t want to be on meds.  My TSH went back up but T3 and T4 held steady (I hope i have the right hormone terms there) and my doc said it means my body is fighting hard.  I have been having trouble losing weight, even though I’m exercising regularly and writing down everything I eat and trying to stay away from carbs and sugar.  It’s very frustrating.  I have energy though, so I hate to go back on the meds.  I hope you will have a better solution for me.

  35. Chris Kresser’s avatar

    That’s exactly my experience with the blood type diet (both personally and with my patients). It works for Type O’s, but not for the other types. That makes sense, because the Type O plan is closest to our evolutionary diet.

  36. Jamie’s avatar

    Given the discussion in the comments on the efficacy of the blood type diet, I thought this recent commentary by Prof Loren Cordain.
    The History And Characterization Of Blood Type Diets

    Blood type diets were first popularized by Peter D’Adamo, a naturopathic physician, in his best selling 1996 book, Eat Right 4 Your Type1. The inspiration for Dr. D’Adamo’s book came from subjective clinical impressions of his father, James D’Adamo; also a naturopathic physician who first proposed this concept in his book, One Man’s Food is Someone Else’s Poison 16 years earlier in 19802. As a member of Bastyr College’s first graduating class of naturopathic physicians in 1982, Peter became interested in attempting to validate his father’s subjective and personal observations from reviews of the scientific and medical literature – thus the fundamental reason for Peter writing his hugely successful diet book.

    The underlying premise for Peter’s dietary ideas is that ABO blood type is the most important issue in determining healthful diets. He advocates separate diets for people with one of the four most common blood types (A, B, O or AB), and has further subdivided his dietary recommendations into three arbitrary ancestral categories: “African, Caucasian and Asian.” Hence 12 subgroups (4 blood types x 3 ancestral categories) exist – each with differing dietary recommendations. Each blood type diet includes 16 food groups which are divided into three categories: 1) highly beneficial, 2) neutral and 3) avoid. For each of the 12 subgroups differing recommendations exist for the three food categories. If these nutritional recommendations sound somewhat complex to you, I had to re-read them about a dozen times to get the drift myself. Although I don’t want to get ahead of the game, for the observant reader, you may be curious to know how Dr. D’Adamo dreamed up this complex dietary system and if a long trail of experimental human clinical trials exist to support Peter’s recommendations? I, too, had to ask myself these same questions.

    Before we get into the science or lack thereof of the blood type diet, I’ve got to flesh out a few more of the underlying concepts. Dr. D’Adamo believes that blood group O (“O for Old”) was the earliest human blood type and that all humans at one time maintained this blood group before the subsequent evolutionary appearance of blood types A, B and AB (reference 1, pp. 6-13). Accordingly, Peter believes that people with the O blood type had ancestors who were skillful hunters and whose diets were high in meat and animal proteins. For modern people with the O blood type he advocates a high meat, low carbohydrate “hunter” diet, with virtually no wheat, few grains or legumes and limited dairy products. Do these dietary recommendations ring a bell for you, or sound vaguely familiar? Keep this thought in mind, as it may well explain the lasting popularity of Peter’s first book.

    Peter now goes on to explain to us that blood group A (“A is for Agrarian”) “appeared somewhere in Asia or the Middle East between 25,000 and 15,000 B.C.” . . . and “allowed them to better tolerate and absorb cultivated grains and other agricultural products” (reference 1, p. 8). For type A’s, Dr. D’Adamo recommends a mainly vegetarian diet – the diet that he personally follows. However, more importantly he recommends that blood type A’s also avoid wheat and dairy (do these recommendations also sound familiar?) and replace meats with some “highly beneficial” fish and seafood – Hmm, lots of fresh fruits and veggies for type A’s, little wheat or dairy and fish instead of meat? Keep these recommendations in mind.

    Peter next tells us that blood type B, “developed sometime between 10,000 and 15,000 B.C. in the area of the Himalayan highlands – now part of present-day Pakistan and India (reference 1, p. 10). Peter suggests that type B’s have evolved the most varied diet and can include both meats and dairy in their daily menu, but again should avoid wheat. Before we move on to the final blood type (AB) it should be noted that Dr. D’Adamo generally eschews highly processed foods (chips, pastries, candy, ice cream, snack food, fast food, etc.) for all blood groups – once again, does this not sound like another familiar dietary suggestion?

    From Peter’s diagram on page 6 of his book, he indicates that blood type AB appeared first in humans sometime between 500 B.C. and 900 A.D. He characterizes “AB is for Modern” and states “Until ten or twelve centuries ago, there was no Type AB blood.” (reference 1, p. 13). Peter indicates that AB’s are a conglomeration of type A and type B blood types, and consequently their diets should reflect a mixture of the recommendations he makes for these blood groups. AB’s are therefore advised to eat meats, seafood and dairy, and to once again avoid wheat.

    The Reality And The Science Of Blood Type Diets

    The reality of Dr. D’Adamo’s book, Eat Right 4 Your Type, is that it has overwhelmingly become one of the sustained, best selling diet books of the past two decades, and continues to sell well on Amazon and other retail outlets – 14 years after its initial release in 1996. Unfortunately, as I will shortly demonstrate, Dr. D’Adamo’s explanations for the health-promoting effects of his diet have little or nothing to do with ABO blood groups. His claims about the origins of human blood types and the dietary selective pressures which elicited the four common blood types are completely incorrect and have no basis in the current scientific literature. By critically examining the faulty concepts and evidence underlying this book, it becomes almost comical how Peter’s series of errors, incorrect assumptions and conclusions actually ended up with dietary recommendations that may have therapeutic value for about 60% or more of the world’s population. The paradoxical nature of this book (bad science, pretty good dietary recommendations) helps to explain its lasting commercial success.

    Actual Origins of Human Blood Types

    Peter’s suggestion that O is the original human blood type is incorrect. Studies in humans, chimpanzees and bonobos (a specific type of chimpanzee) show that alleles (different versions of genes) coding for the A blood type was actually the most ancient version of the ABO blood group, and was shared prior to the evolutionary split between chimpanzees and hominids five to six million years ago3-5. Hence, Peter’s suggestion that blood type A appeared 15,000 to 25,000 years B.C. in response to dietary changes brought about by the new foods (i.e. grains) of the agricultural revolution is not only incorrect, but off base by about five million years. Now, let’s play a little game of logic and apply the correct data to Peter’s reasoning that “the original ancestral human blood type should be eating a high protein meat based diet.” Since type A is the actual ancestral human blood type (rather than O), if we use Peter’s logic then he – himself a type A – should not be following a vegetarian diet, but rather a high protein meat based diet. These kinds of games of logic – although fun to play – more importantly underscore the fundamental and incorrect assumptions upon which Peter’s book is based.

    The next blood type that appeared in the human lineage was B – which split from A – about 3.5 million years ago3-5, not the recent 10,000 to 15,000 years B.C. origin that Peter has proposed. The O blood type split from A about 2.5 million years ago3-5 and consequently does not represent the oldest blood type as claimed by Peter. The only fact that Peter correctly deduced about the origin of human blood types was that AB was the youngest, but once again he completely missed the correct date, as it was actually about 260,000 years ago3 – not the mere 1,500 years ago that he has proposed.

    So Peter has got all of his blood group origins messed up, his dates wrong, and the evolutionary splits incorrect. Why does this matter and how does it affect his dietary theories? To begin with, even if we were to believe in Peter’s underlying assumptions that diets should be prescribed upon blood types, he would have to completely revamp his original recommendations. Type A’s should be eating a high protein, meat-based diet rather than the vegetarian fare he suggests. But what about type O’s? With the correct evolutionary information, should they now be eating a vegetarian menu? And what about type B’s and type AB’s – what should they now be eating? Most telling of the logical failings of Peter’s blood type diet is the observation that all four of the major blood types had evolved almost 250,000 years before the coming of the Agricultural Revolution 10,000 years ago. Yet Peter would have us convinced that three of the four major blood groups only came into existence slightly before or after the Agricultural Revolution, and as a direct result from dietary selective pressures wrought by Neolithic food introductions.

    So, why has Peter’s book become one of the best selling diet books in the past two decades? Because it works – but only for about 44-62% of the people who adopt it. Remember that for blood type O, Peter advocates a high meat, low carbohydrate “hunter” diet; with virtually no wheat, few grains or legumes and limited dairy products. If we look at the frequencies of the four major blood types for the entire world population, blood type O is by far the most frequently occurring version. It is found in 62% of all the world’s people, followed by A (21%), B (16%) and AB (1-3%)6. In the United States, the four blood type frequencies are O (44%), A (42%), B (10%) and AB (4%)7. So you can see that Peter has essentially advocated a diet similar to the Paleo Diet for between 44 and 62% of his readers. Quite simply, Peter’s diet works for about 44 to 62% of the people who adopt it – not because of their blood type, but because it emulates the same diet that natural selection has designed for us all.

    1.D’Adamo, P. with Whitney, C. Eat Right 4 your Type: The Individualized Diet Solution to Staying Healthy, Living Longer & Achieving Your Ideal Weight. Putnam’s Sons, New York, 1996.
    2.D’Adamo, J. One man’s food–is someone else’s poison. R. Marek Publisher, 1980.
    3.Calafell F, Roubinet F, Ramírez-Soriano A, Saitou N, Bertranpetit J, Blancher A. Evolutionary dynamics of the human ABO gene. Hum Genet. 2008 Sep;124(2):123-35.
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    5.Lalueza-Fox C, Gigli E, de la Rasilla M, Fortea J, Rosas A, Bertranpetit J, Krause J. Genetic characterization of the ABO blood group in Neandertals. BMC Evol Biol. 2008 Dec 24;8:342.
    6.Mourant AE, Kopec AC, Domaniewska-Sobczak K. The Distribution of the Human Blood Groups and other Polymorphisms. Oxford University Press, London, 1976, p. 6.
    7.Stanford School of Medicine, Blood Center.


  37. Sara’s avatar

    It is true that the endocrine system is a very complex and if I may say, from my frame for reference, very interesting.  I also find it astounding (and maybe inaccurate) to say 9 out of 10 people with hypothyroid have the autoimmune Hashimoto’s.  This just can’t be!!  But then again, autoimmune dis-ease is so rampant in our society.
    I am an herbalist and cannot disregard that fact the most of these sufferers are women and women have myriad Throat Chakra issues….this should not be excluded.  The emotional variable to any dis-ease should never be left out of the conversation.  With that said, there is also the fact that women are most likely to wear make-up and spray perfumes all over there body, and where else…the neck!!  All these chemicals (endocrine disruptors) in the system are directly correlated to disfunction.  In addition, one cannot ignore the role adrenals play in this situation, with Syndrome X, insulin resistance etc (I know this is another topic altogether).  Diet plays such a huge role, Hashimoto’s or not.  With no antibodies, one MUST look at diet and emotional issues.  And in reading a couple of these posts, it would seem these imbalances are past onto the next generation, which tells me there is not only some learned behavior there, but endocrine system issues from the start. And finally, it’s not only the chemicals we put in and on our bodies that contribute to this, but the deplorable condition of the digestive system and the key role this plays in all our immune functions. I cannot emphasis enough that most every body is deficient in prebiotics AND probiotics and supplementation is crucial. Lastly, mineral deficiencies.  Magnesium, potassium….etc etc.  The SAD diet provides little if any minerals and even if someone eats well (which is relative) assimilation is inefficient due to the digestive flora issues, coated small intestine, and liver/kidney stress do to toxin load.

  38. Karen’s avatar

    This is a great article thank you.  I am hypothyroid and have Rheumatoid Arthritis.  I take LDN (low dose naltrexone) to help with my RA autoimmune disease and am so glad to hear others say it helps with Hashi’s. Chris I look forward to your future articles on thyroid disease.

  39. Andy’s avatar

    “Studies show that 90% of people with hypothyroidism are producing antibodies to thyroid tissue.”

    So that is why in my clinic I treat all thryoid and thyroid like patients with sophisticaltd techniqui of Immunology from the Ling Shu, revealed by Dr Nguyen Van Nghi. (search <>)

  40. Christiana’s avatar

    Just received diagnosis of thyroid auto-immune disease. Longterm stress? Adrenals can no longer react properly? Throat chakra-energy centre-Yes Sara! I am not so into chakra thing but the basic background, premises I find to be good starting points: at some point, some time the person who is dis-eased has had to keep their mouth shut, their spirit shut down.
    The doctor started me on 25 mcg of thyroid. Been taking it for one month. I have found that even that little bit helped me get my energy back and stop thinking that I was losing my mind. But I know this is only a bandage. I have got to work with the stress. Diet. Coffee still tastes good but it doesn’t feel good. Habit makes me want to drink it. So now I just am going to leave it out. Even now I notice that liquorice is a no-no. Going to try it again this weekend to double check reaction.
    Everyone is so different but I think one thing we are all the same on and that is a requirement, a need to have some sort of spiritual life…whatever it is. Diet: elimination diet? I don’t think I am going to get much help from the doctors except for thyroid medicine checks so I go to diet. Leave different foods out of diet for a couple of weeks and reintroduce to see what happens. Any one with experience? advice?
    Anybody have any experience with acupuncture?
    I am glad to find this site. I want to understand better what is going on inside this body that feels like it was falling apart at the seams.

  41. Chris Kresser’s avatar

    I’ll be addressing nutritional strategies for regulating the immune system and reducing inflammation in a future post.

  42. don’s avatar

    I had my thyroid removed in 1968 because of thyroid cancer. for years they had me on armor thyroid, 4 mgs, or something. about twenty five years ago they changed me to synthroid. I have never felt great since the change, the doc’s do not seem to want to change me back to armor, they say synthroid is just as good or better. any thoughts about this.

  43. Chris Kresser’s avatar

    The statement “synthroid is as good or better” than Armour reveals a shallow understanding of thyroid physiology and metabolism. For someone who has problems converting T4 to T3, Synthroid is a terrible choice because it only contains T4. For someone without any conversion problems, Armour may cause hyperthyroid symptoms because it has pre-formed T3. There is no single drug that’s right for everyone.

    There are several considerations when choosing a thyroid medication. I will cover these in detail in a future post. Please stay tuned.

  44. abby shahn’s avatar

    Many years ago, I was diagnosed as hypothroid and prescribed Synthroid. I seemed to have an opposite reaction to the expected one. I gained weight, my hair started to fall out etc. I found a doctor who prescribed something called “thytrophin” .That seemed to work better, so I’ve been taking both for many years. (One to satisfy the doctors and one to feel better.)
    I also had a growth in my thyroid gland and 1/2 of it was removed. The growth was benign and at that point the doctor said that i had Hashimoto’s disease. Now, reading your article I’m wondering how to find out more.
    Are there treatments for autoimmune disease? Are there studies that might clarify some of these things?

  45. Chris Kresser’s avatar

    Stay tuned. I’ll be addressing your questions in the coming articles. Have you read the second one in the series yet?

  46. Chris Kresser’s avatar


    I read the full-text of the China follow-up study Dr. Abraham linked to.  Their conclusion is that excess iodine doesn’t increase the incidence of Graves’ disease.  They didn’t say anything about whether rates of Hashimoto’s increased.

    In any event, there are several other population-based studies that demonstrate this effect, as I’ll share in my next article.

  47. Mario’s avatar

    I know that most recent population-based studies demonstrate that iodinization increased Hashimoto incidence, including here, in Brazil. That’s a fact. But the level of iodine in these populations are very low, compared to what it used to be, and not very long ago. And Hashimoto incidence is higher than it was when iodine level in those populations was higher.
    If iodine was that problematic, Japan would have a much higher incidence of Hashimoto and much worse outcome than they have. Japanese have had allways a very high level of iodine, because of high consumption of algaes, as probably many populations that consumed a diet high in sea food.
    The fact is that bromine, fluorine and chlorine compete with iodine. And we ALL are full of this halides these days. The fact that a little iodine increase in some populations is increasing Hashimoto incidence probably is reflecting this fact with iodine displacing these halides and increasing autoimmune flare.
    Other possibility is that those populations are low in selenium. As you probably know, there are studies that show that populations low in both selenium and iodine, that supplement either one show a high incidence of hypothyroidism.
    Another possibility is that these populations are low in salt. Salt along with iodine is know to increase halide excretion. But, nowadays many people are restricting salt.
    Anyway, what I really know is that Dr. Abraham has been researching this for a long time, Dr. Brownstein has sucessfully treated more than 4.000 people (including him and his father), there are many sucessfully anecdotal testemonies on iodine yahoo group and all these facts made me try iodine, with great success.
    One last thing, if you know a better way of get rid of halides wihout iodine and without moving to live outside of modern civilization, please let me know!

  48. Alisa’s avatar

    Fascinating! I am hoping you can help with a question I have that I can’t seem to find an answer too. It seems easy enough for someone with thyroid knowledge though. I am pretty sure I haven’t had an enlarged goiter, and I have high TSH, with low T4 and T3. All of the writings I have read on Hashimoto’s say goiter and low T4, with no mention of T3, nor stating that you can have Hashimoto’s without an enlarged goiter. Would Hashimoto’s be something I may have (I know you aren’t a physician, but I am just curious if an enlarged goiter and only T4 issues are a must for this autoimmune disorder), or is there another type of thyroid disorder that I may be overlooking.

    It just seems like I will have a better chance to naturally treat this issue and get off of medication if I know the cause. I am otherwise of good health and fitness aside from allergies. Thanks!

  49. Elizabeth’s avatar

    I’ve had hypothyroidism for fifty five years, treated with Synthroid. I’ve never been diagnosed with Hashimotos. I don’t think I’ve ever been tested for antibodies. My lab results over the past three years have been 0.01 TSH, free T4 1.39, free T3 2.1. The T4 and T3 have varied a little, but normal. So my endocrinologist is letting me stay on the Synthroid 137 mcg, until I show signs of hyperthyroidism. I went through four doctors trying to find one that wouldn’t lower my Synthroid dosage. I can’t tolerate a lower dosage, I tried about four years ago. Unfortunately, I haven’t found a doctor in this area who will try natural thyroid.  

    One doctor told me I’ve been on synthetic hormones for so long, that I no longer produce any thyroid hormones at all. About six years ago, I was on 150 mcg, and I felt best on that dosage. Before that, my dosage at one time was as high as 250 mcg. I guess the synthetic dampened down my ability to produce my own hormones. I wish I understood my own situation better.

  50. abby shahn’s avatar

    One thing about natural thyroid, according to the doctors, is that the dose is unreliable. Then an odd thing happened. The local pharmacy used to give me enough synthroid  for three months, but then they discovered that it was degrading on the shelf. That is, the old stuff wasn’t as powerful as the new. All of which leads me to think that the synthroid dose is also unreliable.  I really like that thrytrophin. It comes from a company called Standard Process. My dentist gets it for me,

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