Micronutrient Deficiencies: An Underappreciated Cause of Hypothyroidism

A significant number of our readers have hypothyroidism with normal T4 but low T3. For instance, Kratos:

I followed a strict low carb diet with around 50g of carb per day for over 1 year and I think I have developed hypothyroidism …

TSH 3.4 (0.3-4.0)

FT3 2.2 (2.1-4.9)

FT4 11.4 (6.8-18.0)

This situation can have many causes. Our last post discussed how shift work and disrupted circadian rhythms can cause hypothyroidism. Another often-overlooked cause of hypothyroidism is nutrient deficiencies.

As noted in the book, selenium and iodine deficiencies are classic causes of hypothyroidism. Here I want to look at a few other possiblities.

Copper and Iron Deficiency

Copper deficiency, iron deficiency, and iodine deficiency during pregnancy or infancy generate similar neurological defects, and during adulthood generate similar hypothyroid symptoms:

Cu, Fe, and iodine/TH deficiencies result in similar defects in rodent brain development, including hypomyelination of axons, aberrant hippocampal structure and function, altered brain energy metabolism, and altered neuronal signaling (8–13). In addition, the behavioral and neurochemical abnormalities associated with perinatal Cu, Fe, and iodine/TH deficiencies are irreversible and persist into adulthood (14–16). These similarities suggest that there may be a common underlying mechanism associated with all three deficiencies contributing to the observed neurodevelopmental defects.

Several studies in postweanling rodents show that Cuand Fe deficiencies impair thyroid metabolism. Fe deficiency reduces circulating thyroxine (T4) and triiodothyronine (T3) concentrations (17–20), peripheral conversion of T4 to T3 (18, 19), TSH response to TRH (19), and thyroid peroxidase (TPO) activity (20). Cu deficiency also reduces circulating T4 andT3 concentrations and peripheral conversion of T4 to T3  (21, 22). In addition, Cu deficiency reduces serum and brain Fe levels, which may contribute to the Cu-dependent effect on thyroidal status (23). [1]

In infant rats, deficiencies of either copper or iron cause hypothyroidism:

Cu deficiency reduced serum total T(3) by 48%, serum total T(4) by 21%, and whole-brain T(3) by 10% at P12. Fe deficiency reduced serum total T(3) by 43%, serum total T(4) by 67%, and whole-brain T(3) by 25% at P12. [1]

Note that copper deficiency hypothyroidism reduces serum T3 levels more strongly than T4 levels, the same pattern that Kratos displays.

While We’re On the Topic of Micronutrients and Hypothyroidism …

Hypothyroidism induces the symptoms of riboflavin deficiency. This is because thyroid hormone is needed for production of the enzyme flavin kinase, which is in turn needed to generate flavin adenine dinucleotide (FAD). Riboflavin deficiency and thyroid hormone deficiency lead to the same low FAD levels in both rats and humans. [2]

This suggests that hypothyroid persons may wish to supplement with riboflavin, so that extra riboflavin may help make up for deficient flavin kinase.


I believe that those with health problems should strive to “overnourish” themselves. Micronutrient deficiencies can have insidious disabling effects, yet be impossible to diagnose. In disease conditions, needs for many micronutrients are increased. Many micronutrients are non-toxic up to fairly large doses and can be safely supplemented.

An effort to eat micronutritious foods and supplement micronutrients into their “plateau ranges” to eliminate deficiencies might generate startling health improvements.

Minerals like copper, selenium, and iodine are among the most important nutrients – they are among our eight essential supplements – yet also among the most widely deficient. Most supplementers neglect key minerals; but optimizing their intake can pay large health dividends.


[1] Bastian TW et al. Perinatal iron and copper deficiencies alter neonatal rat circulating and brain thyroid hormone concentrations. Endocrinology. 2010 Aug;151(8):4055-65. http://pmid.us/20573724.

[2] Cimino JA et al. Riboflavin metabolism in the hypothyroid newborn. Am J Clin Nutr. 1988 Mar;47(3):481-3. http://pmid.us/3348160.

Leave a comment ?


  1. I notice that Anthony Colpo makes repeated reference to the fact that high iron levels can be a major player in metabolic syndrome (and worse), and he really feels high iron levels are a major overlooked issue. I noticed the last time he mentioned what his diet consisted of it was mostly eggs, sweet potato noodles, and poultry – i.e a not particularly high iron-diet. That kind of diet, combined with regular phlebotomies, is what i guess he uses to control his iron levels.

    This kind of diet contrasts alot with what the WAPF folks (and some Paleo people) suggest, in that they recommend lots of red meat and esp. organ meat. Doing this would massively ramp up iron intake.

    How can we reconcile high red meat (inc. organ meat) intake which is high in iron, with keeping serum iron levels under control?

  2. Hi Paul – a couple of questions for you:

    After reading the book I started supplementing copper (and all the rest) but stopped it when I recently started eating beef liver again – but am I eating too much liver?

    According to nutritiondata, 81 grams of fried liver has 11.8 mg of copper. I eat about 1/3 kg per week which works out to approx 44 mg of copper if my math is right. The book says to get 2 – 5 mg/day. 5 mg/day would be 35/week – should I cut back a bit on the liver?

    I started eating it for the Vitamin A which I find really helps my skin. I have what looks like keratosis pilaris on my arms & legs, something like acne (I don’t know what type) on my back, and something similar to cradle cap on my scalp – all of which showed up at the same time after I’d been VLC for about 5 months.

    I’ve added back safe starches, mostly white rice & sweet potato, but saw no improvement until I started eating liver, & now only the KP has improved. I do appreciate that it can take much longer for these problems to resolve once diet & nutrients are optimal. While I read the book & got my diet sorted last summer, I only added liver & the B-vitamins a month ago. I’m up to 1500 mcg of iodine but it’s from kelp so I’ll go find a better source asap. I’m ready to double the dose again.

    Speaking of iodine, in another post awhile back, I had mentioned my thyroid surgery 20+ years ago, was on Synthroid for several years & taken off a few years later as TSH levels were within normal range. I can’t find the post right now but I think you said that I’m most likely hypo so I checked with my doc & my last TSH level (a year ago) was 1.3, which she thinks is normal but I now believe is high. She says they do not usually test thyroid hormones if TSH is in normal range. I also asked her what exactly was done in the surgery but that was pre-computerization so they don’t have it on system & couldn’t tell me.

    That test was done prior to finding this blog, reading your book & optimizing diet & nutrients, so I’m looking forward to my next test. I do have some hypo symptoms (hair loss, brain fog, low temp) so I’ll see if I can get them to give me a copy of the surgeon’s report plus I’ll request a full thyroid panel. I’ve read all the thyroid posts here as well as Mary Shomon’s book so I feel a bit more confident going in – but all suggestions are most gratefully appreciated!

  3. Hi Leila,

    Yes, I think it would be good to cut back a bit on the beef liver. You can substitute other organs (heart, kidney, tripe) or liver from non-ruminant animals (chicken liver).

    Alternative sources of A include cod liver oil, chicken liver or other livers, and egg yolks.

    This combination of thyroid surgery, normal TSH, and hypothyroid symptoms is not one I’m familiar with. So I’m not sure I can give you much guidance. You may want to experiment with low doses of Synthroid to verify that it is hypothyroidism and that levothyroxine clears the symptoms. Symptoms trump TSH as an indicator, but a TSH of 1.3 would not normally accompany hypothyroidism.

    If you want a reliable thyroid panel it’s probably best not to increase iodine dose within a month of the panel. However, I would switch to potassium iodide from the kelp. Amazon sells a tablet with 3 mg iodine, you can cut it in half for a 1.5 mg dose.

    Best, Paul

  4. Thank you! You both give your time so generously to writing terrific posts & answering everyone’s questions – I appreciate it more than I can express. Thank you so very much for doing what you do.

  5. This is a really interesting post as I think I have an extreme case of iron affecting thyroid function. I’m always cold. At once point last year I was getting so cold that I couldn’t function, and my toes had no circulation and started to get damaged by it. When I take iron, I warm up. I took twice the daily dose initially (actually only 10mg of ferrous sulphate solution), and think I went hyperthyroid with resting heart rate of 100 and lost 8 lb in the next few months. I cut back the dose after a few weeks – I guess I could tell things weren’t right. I’ve done a bunch of things to improve my diet since then, but I’m still cold all the time (improved but not cured). My TSH is currently 1.5 and my iron stores have been falling steadily over the last year in spite of supplements – at this rate anemia is not far off. I have yet to find an explanation for what’s going on and would appreciate your thoughts.

    • Have you been to a doctor? What have they told you?

      • Yes, I’ve been to a doctor half a dozen times. The first one gave me the standard depression questionnaire and then on my second visit said I should consider CFS. So I changed doctor. This one is more amenable, but the only things that ever showed up in tests as being noteworthy were ferritin and B12 at the low end of normal (normal is too broad but that’s an argument I’m not winning). I suspect we haven’t done the right tests yet, but I’m trying to educate myself so that I don’t waste time by asking for the wrong tests.

        • I would ask for a referral to an endocrinologist / thyroid specialist to chase what is causing the hypo/hyperthyroid fluctuations. Also there are other iron status and anemia tests (see eg http://en.wikipedia.org/wiki/Iron_tests).

          I think this is best chased by a knowledgeable doctor. Good diet and nutrition will help, but doctors are best placed to figure out what is going on.

    • I doubt you will see this, but here goes:

      Anemia and dysfunctional iron metabolism can be caused by copper deficiency.

  6. Hi Paul and Shou-Ching–
    Any thoughts on or experience with available micronutrient tests, such as that from Spectracell labs? Costs aside, it holds out the promise of taking out some of the guesswork… yet I don’t know anything of their reliability.

    • Hi Grace,

      We haven’t looked into that, but we should. I agree that we need to take the guesswork out of nutrition. Especially for nutrients like copper where some people have non-food sources like copper pipes or IUDs; or for nutrients where there is genetic diversity in absorption, like iron.

  7. Hi,

    It seems like you have covered a very comprehensive discussion on hypothyroid. but what about flavanoids?

    There is some research showing some antioxidants such as flavanoids inhibit thyroid.



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  9. I have been suffering too many symptoms to even type here.
    I finally got a Spectracel test that revieled a Copper, Chromium and COQ10 deficiency.All of these have always been in my multi-vitamin!
    Now I cannot seem to find a doctor that knows about this enough to treat it.
    My opinion on Western Medicine could not be lower at this point. Doctor have been telling me there was nothing wrong with me for years. I am only 43 and should not feel like THIS.

  10. Hello,

    I was wondering if you had any insight on the Paragard Copper IUD. Could this cause copper toxicity in a womens body?

  11. I test baseline copper and ceruloplasmin because of this concern http://www.ncbi.nlm.nih.gov/pubmed/20227553, but it’s not supported by literature such as this, looking at serum levels 2 years after implantation: http://www.ncbi.nlm.nih.gov/pubmed/7398904.
    Generally, it’s certainly a better option than a hormonal IUD.

  12. Hi Paul,
    Are there any test panels that you recommend that you recommend to individualize supplementation?

  13. Dear Paul,
    Your Blog is a rational lifesaver. Sometimes one gets lost in life with cults or conspiracy theories. For me this was Ray peat’s dietary advice forums. I have never done well on fructose or even much glucose, and getting off low carb because of peat was the worst health decision of my life.
    I had euthyroid sick syndrome recently-high tsh normal t3/t4 -no test for rt3, and I now realize it may have been because of :
    Excessive blood donations(1 litre a year for 3 years)
    Excessive caffeine intake(prevents iron adsorption)
    High stress (from bad work environments and caffeine)
    FAR FAR too much protein intake relative to sat fats and carbs.(I think high protein is key as a stress inducer and also due to insulin response etc.)
    Do you reckon excessive blood donation could lead to iron deficiency induced hypothyroidism?

    • Hi Shah,

      Iron deficiency is easy to test for. It’s unlikely those blood donations would induce iron deficiency in a man, but in a menstruating or pregnant woman might have an impact.

      Best, Paul

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