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19 Apr

5 Common Nutrient Deficiencies (and What to Do About Them)

If the Primal way of eating is so healthy, why am I writing a post on common nutrient deficiencies? Well, mostly because you asked. For months now, I’ve received emails from Mark’s Daily Apple readers asking about iodine, selenium, magnesium and other vitamins and minerals, so I figured it’s about time to highlight these key nutrients, explain how and why some people find themselves deficient and provide my opinion as to what they can do about it.

I also wrote this article to make the point that quitting grains, legumes, seed oils, and sugar is just part of the equation. There’s a whole lot more to healthy eating than just deciding what not to eat. You also have to be mindful of the things you do eat, and – hopefully – those things will be incredibly nutritious.

Consider this post your guide to avoiding some of the most common nutrient deficiencies. Let’s jump right in…


Iodine is a trace mineral with big implications for our health, especially of the thyroid. Although most assume deficiency is relegated to developing nations, recent research has found deficiency in places like the UK and France.

Deficiency Symptoms

  1. HypothyroidismIodine is a crucial ingredient in thyroid hormone, so a lack of iodine in the diet will reduce the thyroid’s ability to manufacture thyroid hormone. Symptoms of hypothyroidism include weight gain, an inability to lose weight, fatigue, elevated blood lipids, hair loss, dry skin, loss of libido, infertility, to name a few.
  2. Goiter – In an iodine-deficient state, the thyroid gland will enlarge in order to overcompensate. This will often result in a highly visible lump in the neck.
  3. Cretinism – Iodine deficiency during pregnancy often results in abnormal neurodevelopment and lowered IQ (PDF) in the child.

Why Might Deficiency Occur?

  1. Removal of iodized salt from the diet. Most table salt is iodized with the minimum required dose, but when people switch to a whole foods, Primal eating plan, they’ll often reduce their salt intake and switch to sea salt (which contains trace minerals but insignificant amounts of iodine).
  2. Lack of iodine in the soil. Although iodine concentration remains pretty constant throughout the ocean, iodine content of soil varies dramatically by region, with some areas having so little that they’ve earned the term “goiter belt.” Coastal areas tend to have higher soil iodine levels, due to absorption from atmospheric iodine (which in turn comes from the ocean), but very little solid data exists on the iodine content of soil by region.
  3. Insufficient intake of iodine-rich foods, like seaweed and seafood.
  4. Excessive intake of goitrogen-rich foods, which interfere with iodine uptake by the thyroid gland. This, then, isn’t a true whole-body deficiency, but rather an inability of the thyroid to get the iodine it requires.

Where to Get It

  1. Eat seafood, fish, shellfish, crustaceans, and basically any creature that lives in the ocean. Iodine content of fish varies, but you can get an idea from this Japanese analysis of commonly eaten fish. Looks like pollack, codfish, and abalone rank highest, but there are lots of good sources. Cooking method will also determine iodine content, with boiling losing the most and frying retaining the most (PDF). Grilling retains far more iodine than boiling, and just a little less than frying, so that’s probably a nice middle ground between boiling and fish sticks. Iodine in the boiling water, however, accounts for most of the lost iodine, so you could do something with the water. Raw seafood will retain the most iodine.
  2. Eat seaweed, especially hijiki and kelp (or kombu). Drop a dried strip in your next pot of soup, chili, or curry, or, better yet, put several strips in your next batch of bone broth along with the bones.
  3. Eat pastured egg yolks (PDF). Although the specific amount depends on the dietary iodine of the laying hen, if there’s iodine in the diet, it’ll show up in the yolk. After all, chicken baby brains need iodine just as much as human baby brains.
  4. Supplement. Popular ones include kelp supplements, Lugol’s solution, Iodoral, and Iosol.


RDA is 150 micrograms. Seaweed-eating Japanese populations often get upwards of 12.5 milligrams (or 12,500 micrograms) per day, while the general Japanese population gets beween 1-3 mg per day. 150 mcg should be the bare minimum, and if you’re feeling any of the deficiency symptoms, consider increasing your intake. Paul Jaminet recommends starting low (500 mcg/day) and slowly increasing intake by doubling every month. As I mentioned here, you’ll also want to make sure you’re getting enough selenium (see below) before increasing iodine intake. If you stick to food sources, you’re not in much danger of going overboard.


While severe selenium deficiency in adults is pretty rare, minor deficiency is easy to get and can have some unpleasant effects on our health.

Deficiency Symptoms

  1. Selenium supports efficient thyroid hormone synthesis and is required for the conversion of thyroid hormone T4 into the active T3, so a selenium deficiency can manifest with hypothyroid symptoms (see above).
  2. Selenium deficiency symptoms look an awful lot like the side effects of statins, especially muscle damage and polyneuropathy.

Why Might Deficiency Occur?

  1. Lack of selenium in the soil. Lack all other minerals, selenium must be present in the soil to show up in the food. It isn’t created out of thin air. If you’re in the United States, this map should give you an idea of how much selenium is present in soil near you (or, more importantly, wherever your food is grown).
  2. Insufficient intake of selenium-rich foods.
  3. Intestinal disorders, like Crohn’s disease, ulcerative colitis, and celiac, can reduce the absorption of selenium from foods.

Where to Get It

  1. Brazil nuts (one or two a day are enough to improve selenium status), wild salmonkidneys, crimini and shiitake mushrooms, lamb, turkey, shrimp, cod, halibut, and egg yolks are all good sources of selenium.
  2. Supplement. Selenomethionine is the form found in plants, while selenocysteine is found in animals.


200 mcg appears to be the safe supplemental dose, but there’s very little evidence of selenium toxicity from a diet high in selenium rich foods, so that Brazil nut-encrusted salmon kidney in shiitake/crimini mushroom sauce with a turkey egg omelet should be safe.


Ah, magnesium. Everyone touts its importance, and yet few seem to get enough through diet. In fact, most research suggests that only around half of US adults reach the RDA, with low intakes being linked to type 2 diabetes, metabolic syndrome, osteoporosis, heart disease, asthma, and colon cancer.

Deficiency Symptoms (Just Some of Them)

  1. Insulin resistance.
  2. Constipation.
  3. Migraines.
  4. Restless leg syndrome.
  5. Cramping.
  6. Hypertension.
  7. Fibromyalgia.

Why Might Deficiency Occur?

  1. Lack of magnesium in the soil. US readers, check out this magnesium soil content map (similar to the selenium soil map) to see how you do.
  2. Lack of magnesium-rich foods in the diet, particularly plant foods. Animal foods are relatively magnesium-poor, while plants tend to be magnesium-rich. How many people do you know who really eat lots of leafy greens? Both Primal and SAD eaters are therefore at risk.
  3. Removal of magnesium from drinking water. I suspect magnesium-rich water (as opposed to purified, depleted modern water) was how Grok got a lot of his magnesium.

Where to Get It

  1. Leafy greens, especially swiss chard and spinach.
  2. Nuts, seeds, dark chocolate, espresso, and halibut.
  3. Mineral water. One brand, Gerolsteiner, is particularly high in magnesium. Or you could find a spring nearby for some real (free) spring water.
  4. Supplement. The chelated magnesiums (those ending in “-ate,” like citrate, glycinate, or taurate) tend to be the best absorbed. You can also apply magnesium oil topically for transdermal absorption. In my experience, transdermal magnesium absorbs best on the rib cage and inner arms (you’ll know from the tingling and the vivid dreams).


400 milligrams daily is the minimum, I’d say. Aim to get it from food if possible.

Vitamin K2

Most people haven’t even heard of vitamin K2. Is it any surprise that they might be a bit deficient, too?

Deficiency Symptoms

  1. Tartar buildup on the teeth, and eventually tooth decay.
  2. Osteoporosis.
  3. Arterial calcification, and maybe heart disease eventually.

Why Might Deficiency Occur?

  1. A total lack of knowledge of the vitamin’s existence. If you don’t know about it, you can’t go out of your way to obtain it.
  2. A lack of vitamin K2-containing foods in the diet. Even if we’re aware of K2, it’s available only in select foods.
  3. A lack of vitamin K-containing foods in the diets of the animals we eat, thus giving them nothing to convert to vitamin K2 via gut fermentation. Cows raised on pasture are able to convert the vitamin K1 in grass to vitamin K2; cows without access to pasture will have very little K1 to convert.

Where to Get It

  1. Food. For the animal form, MK-4, you need to eat pastured yolks, goose liver, grass-fed butter, aged cheese, and fish eggs. For the vegetable form, MK-7, natto – the traditional (and sticky) Japanese fermented soybeans – is your best bet. Of course, we don’t know exactly how much K2 is in any of these foods without extensive testing, and none of the online nutritional databases include vitamin K2 in their analyses. Therefore, the safest route is the one that involves eating lots of the aforementioned foods (tough, huh?).
  2. Food-based supplements like high-vitamin butter oil.
  3. Straight-up supplements, like Thorne MK-4 drops or Life Extension, which has both Mk-4 and Mk-7.


It’s tough to say. Studies on osteoporosis and heart disease use rather large doses (45 mg/day) without ill effect, but the amount you’d get from food is far lower – maybe 1 mg, max.

Vitamin B12

According to Chris Kresser, vitamin B12 deficiency is quite common, even among those who eat plenty of the richest source of B12: animals.

Deficiency Symptoms

  1. Lethargy.
  2. Unwanted weight loss.
  3. Dementia/Alzheimer’s-like symptoms.
  4. Anxiety and depression.
  5. Autism spectrum disorder in children.

Why Might Deficiency Occur?

  1. We aren’t looking for it. As meat-eaters, we assume we’re getting plenty, and doctors don’t check for it regularly.
  2. We aren’t absorbing the B12 in our food. Gut disorders like Crohn’s or diarrhea affect our ability to absorb nutrients, minerals, and vitamins, including vitamin B12.
  3. We set the bar for “normal” too low. Everything could check out and look fine on paper, but the lower end of “normal” is too low and can still cause B12 deficiency symptoms. Other countries, like Japan, have higher “normal” B12 markers and fewer cases of Alzheimer’s/dementia.

Where to Get It

  1. Animals. Liver, sardines, and salmon rank highest, with liver running away with it. There are no vegetarian sources.
  2. Supplements. Methylcobalamin is probably the best.


If you eat animal products regularly and liver occasionally, you’ll be getting plenty of B12 in your diet. No need to supplement if you have none of the symptoms listed above. But if you have some of the symptoms, or you have a gastrointestinal disorder that may be compromising your ability to absorb vitamin B12, consider getting your levels tested during your next visit to the doctor. In that case, Chris recommends 1 mg/day of sublingual methylcobalamin, which will bypass the intestinal tract and pass directly into the bloodstream.

Do any of these sound familiar? Are you getting enough of these nutrients? I hope so, and if not, now you know how. And if there are any other nutrients you’ve been wondering about, let me know in the comments and maybe I can get a sequel going. Thanks for reading, folks.

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. If you are hypothyroid, I highly recommend that you DO NOT TAKE OR EAT IODINE!!! I followed this advice a year ago from a dr’s blog to increase my iodine for low thyroid and ended up causing an autoimmune response because iodine can attack your thyroid. I ended up diagnosed with Hashimoto’s Thyroiditis. Not fun! Well meaning advice from Mark and others, but those of us with thyroid problems don’t need anymore issues! Thyroid experts say taking iodine is like throwing fuel on a fire!

    Jan J wrote on April 19th, 2012
    • Agree, however I’m not sure it can trigger an autoimmune disease – it was probably there before but taking iodine made it more obvious.

      Allison wrote on April 19th, 2012
    • A very full account of the role of iodine and autoimmune response can be found it this two part series.

      “A survey of the literature suggests that Hashimoto’s is largely unaffected by iodine intake. However, the literature may be distorted by three circumstances under which iodine increases may harm, and iodine restriction help, Hashimoto’s patients:

      1. Selenium deficiency causes an intolerance of high iodine.
      2. Iodine intake via seaweed is accompanied by thyrotoxic metals and halides.
      3. Sudden increases in iodine can induce a reactive hypothyroidism.

      All three of these negatives can be avoided by supplementing selenium along with iodine, using potassium iodide rather than seaweed as the source of iodine, and increasing iodine intake gradually.”

      Jo wrote on April 19th, 2012
    • What kind of Iodine did you take?
      Iodoral cured my Hashimoto’s

      Jennifer wrote on September 3rd, 2014
  2. Many thanks for this informative post. For a few years I refused to take supplements, believing I was getting everything I needed from my healthy diet but recently I’ve come around to the way of thinking that the fruit and veg I eat has lost a lot of nutrients by the time it gets to me. Also the soil it grows in is depleted of nutrients. As a vegan I have to be careful too so I thought it was better to cover my bases and take a supplement. Even meat eaters can be just as deficient. In the North of Scotland we don’t get much sunshine so we are also lacking in vitamin D here.

    Katherine Natalia wrote on April 19th, 2012
  3. Minerals “must be present in the soil to show up in the food. It isn’t created out of thin air.” Yes! Thank you!

    Years ago, before I found this website and was just beginning to get my diet on track, I was told by a friend that eating organic vegetables was a waste of money because “her friend’s medical school professor told them of a study that proved that organic and conventional vegetables were the same, nutritionally.”

    Now I thought that was just about the dumbest thing I’d ever heard. I was so struck by the stupidity of it all that I was momentarily speechless. I knew plants couldn’t manufacture minerals out of thin air. How could science defy common sense?

    If I remember correctly, I later learned that the “study” in question compared conventional, big-agra vegetables to organic, big-agra vegetables, the only difference between the two soils being that the latter didn’t have pesticides, etc. Is it really that surprising that there was no difference in the nutrients?

    Renee wrote on April 19th, 2012
    • There are have been several studies that show this but I don’t eat organic to get more vitamins or minerals, I eat it because I want to avoid pesticides and other unpleasant additives. I believe that these studies are done to deliberately cloud the issue of organic food claiming that is is no healthier than ‘normal’ food. Seems to me that these are badly framed studies designed to avoid the real issues of pesticides and additives in the food chain.

      Jo wrote on April 19th, 2012
      • Exactly. And that’s what I wound up telling her, that even if there was no nutritional difference, it would be worth eating organic to avoid all the pesticides, etc.

        Renee wrote on May 10th, 2012
  4. I eat Those things…
    Im doin great!
    GROk On>>>

    Dave PAPA GROK Parsons wrote on April 19th, 2012
  5. Great post! I learned so much from this post thanks so much!

    CourtStar wrote on April 19th, 2012
  6. If you can get your hands on it, Excelsior Springs Natural American Mineral Water is great stuff. They don’t ADD minerals, they occur naturally, more kinds than anyplace in the world except Baden-Baden. The one that’s currently bottled has Calcium, Potassium, Magnesium and Bicarbonates, and it’s GOOD. I believe they will ship, check the website at (And no, I don’t own stock! I just drink a bottle every day…)

    Cathy Johnson (Kate) wrote on April 19th, 2012
  7. Mark: I definitely would love to see some attention for zinc deficiencies if you write a follow up post, however with zinc it’s not necessarily just a deficiency that can be a problem but also its balance with copper.

    Zinc is known to be needed in 200+ various reactions in the body, so a deficiency or imbalance has far reaching effects, notably with the immune system, skin health and even mood. I personally think zinc is one of those absolutely essential nutrients that should be monitored.

    Allison wrote on April 19th, 2012
  8. Steven wrote on April 19th, 2012
  9. Is there a test you can get that measures your levels of things like this? I know for example that it’s common to test for vitamin D levels, but for all the other ones (like those listed in the article and mentioned in the comments) is it as simple as requesting them from your doc?

    Cassie wrote on April 19th, 2012
    • I would also be intereseted in knowing of a way to test for all of these levels.

      Paul wrote on April 20th, 2012
    • A good test for magnesium and potassium is the EXATest ( These two are intra-cellular minerals, and standard lab tests for these minerals look only at extracellular blood serum. The downside is that these tests aren’t usually covered by insurance, and your doctor might not believe that these tests are valuable and refuse to order them, especially if they work for an HMO.

      jake3_14 wrote on April 27th, 2012
  10. Great article to bring awareness to certain deficiencies. I’m noticing a lot more mineral deficiencies with my clients…

    I’ve used celtic sea salt in my water to aid in mineral supplementation…do you think that this is a good strategy?

    Alby wrote on April 19th, 2012
    • yes

      Jennifer wrote on September 3rd, 2014
  11. This is such an informative post. Well-timed, too! Thank you Mark!

    pat wrote on April 19th, 2012
  12. What an excellent resource, Mark. So clear and thorough. And much-needed. Thank you!

    Susan Alexander wrote on April 19th, 2012
  13. I’m another person who wanted to point out zinc deficiency. My daughter was deficient and it caused a whole host of problems, the weirdest symptom being that she had a super sensitive sense of smell and lots of foods completely grossed her out.

    Laura wrote on April 19th, 2012
  14. I don’t know how is it available in other places, but in Slovenia, natural mineral water called DonatMg is known for it’s magnesium content. It is over 1000mg/l

    People in Slovenia are also drinking it for helping indigestion and constipation issues.

    Perun wrote on April 20th, 2012
  15. Though I support the notion of supplementing yourself with natural foodstuff to fill up your deficiency, sometimes you do need supplement salts. Just for e.g. I have migraine and I have been researching which Mg salt I should be taking, although MgO is mostly recommended, only 4% of which is absorbed. There are many arguments and counter arguments for many salts so I wonder if you could update the article with that information.

    Same goes for B12, I am ulcerative colitis patient too so my doc asked me to take 1000mcg of B12, I started taking cyanocobalamin, most widely available form. Reading through literature got me the news that Methylcobalamine is a better form.

    The supplement industry makes consumer more difficult to choose the product, as they say, if you can’t convince the consumer, confuse them, thats exactly what they do.

    Noel wrote on April 20th, 2012
  16. Gerolsteiner! Awesome! I drink it all the time and loooove it. 😀

    Steph wrote on April 20th, 2012
  17. I almost died because of a B12 deficiency. It will cause myoplastic anemia (where the body doesn’t make enough red blood cells and the ones that are there are HUGE and fluffy, and essentially useless)
    I had to have a 4 pint blood transfusion, could have used 6… but the drs were worried I would start to reject the blood if I went that high.

    I now have bi-monthly shots as well as 5000mcg daily. I have to take them under the tongue because my gut wasn’t absorbing what I was eating.

    Angelia wrote on April 20th, 2012
  18. Dr. kruse has a blog post on the top 10 most important supplements for paleo eaters.

    Greg wrote on April 20th, 2012
  19. Great post! Just proves once again that through becoming so out of touch with nature and living so far removed from how we were supposed to live (ie pretty much like Grok!), we have caused so many knock on effects!

    Guess its Kalma, we abused the earth and now this is payback!

    H x

    HelenC UK wrote on April 21st, 2012
  20. I eat kelp everyday. Iodine deficiency is one thing I don’t have.

    Caleb wrote on April 21st, 2012
  21. I’ve never heard of k2 studies using 45 mg…that’s a massive dosage. Did you mean 45mcg? The life extension formula is great…

    Robert wrote on April 22nd, 2012
  22. If I might add, you forgot to mention vitamin A.

    It’s a myth that everyone gets all the vitamin A they need from beta carotene. A couple small studies in the U.S. and UK showed that as many as 49 percent of the population aren’t converting enough beta carotene to meet all their vitamin A needs.

    Plus, people with hypothyroidism, type 2 diabetes, and certain other health conditions can’t convert beta carotene at all. I would imagine people missing their gallbladders are going to have some trouble as well, as bile salts are involved in the conversion.

    Additionally, children under 5 and the unborn are not yet able to make the conversion.

    And finally, when you get a surplus of real vitamin A in your diet, your liver stores the extra for later. But if you’re depending on beta carotene for your A, and that’s if you can convert it in the first place? Your body only converts enough beta carotene to meet your A requirement *for that day.* The excess beta carotene is not stored in the liver for later; rather, it’s put away in your body fat. (This is why food animals eating a lot of carotenes wind up with yellow body fat!) You can’t then take it out later to turn into vitamin A; instead, you must eat more beta carotene. Too many days of not eating enough carotenes and you go straight into deficiency.

    I know the experts say that pregnant women getting vitamin A leads to birth defects but they did not differentiate between real and synthetic retinoids for the purposes of their research. We know synthetic A causes birth defects in high enough doses. But going without real vitamin A means your baby will have birth defects anyway. If you’re deficient early in the pregnancy, your baby will have vision problems; if you’re deficient later in the pregnancy, there will be urinary tract defects.

    Interestingly, the Mayo Clinic says urinary tract defects are the most common type of birth defects occurring in the United States. Just as a data point.

    I suspect a lot of the fertility and heavy/painful menstruation issues we’re seeing in women now come from vitamin A shortages as well. Certainly I cured some of my own problems by supplementing it. It is one supplement I never go without now–and as with B12, it’s cheap and easy to obtain. Just make sure the label says “sourced from fish liver oil” or similar, take it paired with vitamin D (in a 10:1 A:D ratio or better–i.e., 9:1, 8:1, and so on) and you’ll be fine.

    Dana wrote on April 22nd, 2012
  23. Great article Mark. I would love to see a follow-up post discussing vitamin D, iron, and white & red blood cell deficiencies. Also, with eating Paleo over 8 months now (lots of grass fed red meat and liver), one would think iron deficiency would be a problem of the past. However, this isn’t the case for me and I am beginning to wonder if I’m experiencing issues with absorbing nutrients. Can you discuss absorption of vitamins & minerals i.e. what are the causes (besides sugars and grains) and what can be done to improve absorption i.e various foods, supplements, herbs, etc. Ultimately, my goal is to rely solely on wholefoods eating to get all my required nutrients (reduce/omit supplementation as much as possible).

    Thanks Mark!

    Chika wrote on April 23rd, 2012
  24. There are some animal foods high in magnesium. Here’s a list showing mg of magnesium per 100 g of food per USDA nutrient database.

    300 caviar
    250 snails
    97 mackerel
    86 pollock
    55 scallops
    54 oysters
    42 cod

    Some common plant foods with no phytates to bind the magnesium:

    121 kelp raw
    86 swiss chard cooked
    82 frozen spinach cooked
    79 spinach raw
    68 beet greens cooked

    I’ve been trying to eat more mackerel and spinach lately :)

    Bryan wrote on April 26th, 2012
  25. After being brought to my knees in despair & spending most days in bed except to care for my grandkids I began “doctoring”. Having been molested by my PT due to neck trauma from having most of my thyroid removed (and my 3 out of 4 parathyroids were also removed in a botched surgery by accident & not informed) I didn’t see a dr for 17yrs drs except emergencies. I am still on a quest to heal chronic depression since 2000 among other probs due to the botched surgery. To make this long story end I found from my great new dr that my vitamin D levels were as low as considered ok. This has now been upgraded. My dr put me on D fairly high dose but what I felt in my body was improvement of depression. By no means am I “healed” but you take what you can and being in very north of the states sunlight is not enough. Hope this helps someone-vitamin D!

    Diana Mantese Tutt wrote on April 30th, 2012
  26. No vegetarian sources of b12?? You should try nutritional yeast.

    Dstring wrote on May 1st, 2012
  27. Yeast is not vegetarian.

    Mike wrote on June 7th, 2012
    • My meaning simply being, yeasts are not plants! (Just being cheeky, friends!)

      Mike wrote on June 7th, 2012

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