Clay Cookware – Safe or Toxic?

posted in: Kitchen, Safe or Toxic? | 65

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Clay cookware

A few months ago I decided to test clay cookware (aka earthenware). And here is what happened. In the light of concerns about lead and cadmium in ceramic dishware and cookware, I was delighted to find Miriam’s Earthen Cookware. On her website, Miriam features a report confirming that there is zero lead and cadmium in her clay cookware. After talking to Miriam in person for almost an hour, I felt confident enough to give Miriam’s Earthen Cookware a try. So I bought her large clay pot for a hefty price.


It took awhile for the pot to show up but it arrived well packed and in good order. I studied the detailed instructions on how to season Miriam’s Earthen Cookware pot and followed them. I was extra careful to follow all the instructions so I did not damage such an expensive clay pot.


Clay Cookware
Seasoning Clay Cookware

After seasoning the pot, the first thing I cooked in it was beef bone broth, which was not very convenient because the water evaporated even faster than from a stainless steel pot. I had to set up an alarm in the middle of the night to add water. The aroma of the broth mixed with the scent of clay remained in the house for a few days. I was willing to overlook these minor difficulties because the broth was delicious. However, I could not help but taste a subtle hint of clay.


The taste of clay became more prominent when I cooked beans in the pot. Actually, after I ate the beans I continued having a clay aftertaste in my mouth – for four days. I also felt tired. I thought that maybe something else gave me the weird aftertaste. I had recently started taking probiotics and an herb, and stopped taking them in case they were the culprit. Finally, the aftertaste was gone and I was not quite sure whether it was caused by Miriam’s clay cookware, especially because my husband did not experience the same problems.


So a week later I cooked something else in Miriam’s clay cookware. This time, it was a chicken broth-based soup. The broth had been cooked previously in another pot I had used for a long time. The clay aftertaste came back and I felt really run down. It took me about a week to fully get rid of the haunting clay aftertaste. As for the energy, I felt a lot better after a few doses of N-Acetyl Cysteine, which helps detoxify heavy metals.


When I talked to Miriam, she suggested that my condition might have been caused by the fact that food made in her clay cookware is so nutritious and my body simply was not used to handling the extra nutrition. She said that I might stop taking my multi-vitamins and give the clay cookware another try.


I expressed my curiosity about the composition of the clay she uses. I had learned clays have a variety of ingredients, from nutritious things like calcium and magnesium to potentially harmful things like aluminum and antimony. Here is an example of clay composition. On her website, Miriam has a full list of nutrients and micro nutrients found in the clay. This is different from a full list of ingredients that make up the clay.  Miriam said that she has the full of list of the ingredients she uses, but it is proprietary information. When I am asking tough questions of manufacturers, I hear this “proprietary information” phrase very often so I am well prepared for it. What I was not prepared for was what came next. Miriam suggested that I call the lab and ask for the test results directly from them. I did, but as you can imagine, the lab did not release any information to me as I was not their customer.


So, we do not know what is in the clay, which is important. Why? Because the clay pot has no glaze that creates a barrier so whatever is in the clay can leach into food. This study published in the journal Science of the Total Environment (vol. 409 (15) – Jul 1, 2011) detailed the results of testing of glazed and unglazed clay cookware. The study focused on arsenic and it was found that arsenic leached up to 10 times more from unglazed earthenware. The scientists concluded that the risk of arsenic poisoning is high enough to be of concern and warrant regulation. By the way, arsenic is not so uncommon in clay as it was detailed by the UK’s Foods Standards Agency.

Clay cookware - Safe or Toxic?


Please do not get me wrong. I am not suggesting that I was poisoned by something that leached out of the clay. The purpose of this write up is to share my experience with Miriam’s Earthen Cookware, educate others of possible downfalls of clay cookware, and provide a platform for sharing experiences with clay cookware. Please let me know if you have used clay cookware and what you thought. Please forward this blog to whoever you think might be interested. And if you’d like, please come by our house and take this clay pot from us because we do not know what to do with it. Unfortunately, Miriam’s return policy is no return.


Disclaimer: I could have received commissions for promoting Miriam’s Earthen Cookware.


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65 Responses

  1. I am so curious I almost want to try it myself!! I would check a urine test for heavy metals $60. Fascinating! There are some people who have an immune reaction to some substances. So it could be that most people don’t have a reaction to this pot, but a few might.

    • I know. I am curious, too. Let me know if you’d like the pot. 🙂

    • Here is a question. Do you think I can send the lab vinegar solution boiled in the pot? I assume I would have to send a control sample, too.

    • After I read your post I hesitated a bit to buy these pots but my sister has been insisting that I do (they have the whole set and love it). When I finally bought them I regretted that I had waited so long. I was so wrong, these pots are really good. I’ve never tasted food so good, the lentils, beans, vegetables, grains, meats all come out fantastic! There are 2 things that I did that made me go for it… I looked through their site thoroughly and found the test results for the complete composition of the clay and there is no arsenic in the clay (this is the only cookware i found that did such a thorough testing and this is tested in the USA). And b. Since I live not very far from their workshop I visited them and was amazed at how hard they work to make a pure and uncontaminated product. If you know primary clay you will know that it does not have any heavy metals and that is what they use… their clay is 100% natural primary clay. The ceramic (or artificial clay) is what has heavy metals including arsenic and that is why glaze is used in the 1st place.

      Yes, they are pricey but totally worth it. We now cook all our food in these pots and so do a lot of my other family members.

  2. I find this so fascinating!! I also tried a clay pot from MEC but didn’t experience that at all! I actually really liked the flavor of the food I cooked in it. I found that the clay really did smell like the food I cooked in it for awhile afterwards, though.

    • Hi Judith: I often find that my experiences differ from the green blogger community. I do not do that on purpose. 🙂 Thank you for sharing. It is your review I found I was looking around the Internet for more information on MEC. Thanks!

      • I’m glad you are honest! But I’m sorry that you didn’t have a better experience with it.
        I take multi-vitamins and probiotics daily as well. I wish I had a better answer for why you experienced what you did!

  3. Hi Irina,

    I bought Ceramcor/xtreama cookware as suggested by you. Even that’s not good?

  4. Wow! Thank you for sharing your experience. I haven’t gotten down the path of clay cookware, but have considered it. I did find it a bit peculiar that she would not share the proprietary blend. I understand it could be what sets her clay cookware apart, but it also makes it seem like there could be some answers to the reaction you had. I hope she does her own research so she can answer your questions in the future.

  5. Listening Bee

    Hi Irina,
    I wish your article had come out a couple of months ago when I started looking at safe cookware options. Reviews on these MEC pots were hard to come by. The only thing I found consistently would be a lone user comment in a “healthy” cookware article that would say how much the user loved his/her MEC cookware.
    But after reading through the MEC site, I thought I would give one a try. These pots cost a pretty penny, but the website claimed that they were fully tested and certified to be free of lead, cadmium and heavy metals. Plus, they are made in the USA.
    My experience? The clay did affect the taste of my stew, and the stew affected the smell of the clay pot. My family and I did not experience any ill effects as you did, but I found taking care of the pot required more time than I wanted. Plus, even after cleaning the pot several times, it still gave off a smell in my kitchen. I, too, have a free pot for anyone who wants it.

  6. Irina,
    Still go back to my original proposal to you. You’ll never get the truth from business people. We need to find a socially minded scientist or food chemist to assist in this search for clean, healthy cookware. We can all chip in a little. I will.

    • Hi Eliot: I agree! I hope we will “catch the right person with my blog” soon 🙂 By the way, you will be pleased to know that I am going to Hawaii next week and I am planning to unplug for almost 10 days. It is going to be the first time for me in 2.5 years.

  7. Kayleigh

    If you still have the clay pot around I’d take it. My sister is a biologist and might be able to tell more about it’s composition. She loves natural materials but is also very concerned about safety of today’s cookware options. I live in CA though so not sure if that’s too far to send it.

  8. Hi Irina,

    I was just wondering if you’ve found any new information about this?

    I’ve been using an MEC pot for several months and have not experienced that problem. The first few times I used it, I definitely noticed a smokey smell/taste to the food, but that has gone away, and everything from the pot now tastes great.

    I remember I made a tomato sauce before the pot was fully ‘seasoned,’ and there was a lot of perspiration on the bottom of the pot, and it seemed to be leaking. I reached out to their customer service, and they said “It’s recommended that you use the pot for several hours of cooking only after it’s used at least 5-6 times cooking wet recipes that take less than an hour.” So I am wondering if making the bone broth before the pot was fully seasoned was part of the problem. I hope these pots prove safe as I love cooking with it.

    Anyway, that’s my two cents. Thanks for being such a great advocate!

    • Hmm… Maybe… I am glad that the pot worked for you. I decided to stop experimenting with it and gave it away. I am curious who you spoke with when you said “customer service.” In my experience, Miriam is the only one who answers the phone. I spoke with her multiple times and she never mentioned that to me. I remember that the pot had to be used 5-6 times before you can start making food without using oil. Anyway, I do not want to risk getting sick again. But thank you for sharing your experience!

  9. Hi Irina, I’m wondering if you know the Emile Henry line of cookware and your opinions on it.

  10. So, what do you suggest instead of MEC?

  11. I just found out recently that Emile Henry is not lead free and does have lead in it when tested. So that’s a bummer because I wanted to purchase some of their stuff. The best I could come up with so far is Pyroflam (from Pyrex) but it’s only available in Europe and may be hard to clean. The pros, however, are that it’s all glass (including the steamer insert) and glass ceramic which is lead free. After that, I would go with the tried & true Le Creuset for skillet and dutch oven. MEC totally sounds like a hard cell and the other one that is all-black ceramic cookware made in China (forget the name), sounds like a hard sell as well.

    • I’ve heard that of Emile Henry also, although I’ve never been able to contact anyone at Emile Henry to confirm or deny such claims (it could just be angry customers spreading rumors). I’ve also emailed back and forth with Le Creuset and they informed me that their bright colors are not lead free (they claim it is needed to achieve the bright oranges and reds). Also, while some Le Creuset is still made in France some of their products (such as their stoneware) is now being manufactured in China and Thailand.

    • do you suggest pyroflam over pyrex? if so, why? is this your number 1 cooking vessel?

      • Hi Emily, thank you for asking. Yes, I like Pyrex and use it a lot. I have not used Pyroflam yet. Have you used it? Glass is the most inert material so it is the safest. Your question inspired me to write a blog post on glass cookware. Stay tuned. ~Irina

      • Hi Emily, Eliot, one of my blog readers, who is also a restaurant owner and a holistic nutritionist, points out that there is a problem with Pyrex bakeware exploding. It appears that in 1998 Pyrex switched from borosilicate glass to soda lime, which often fails to withstand drastic temperature changes. Pyrex bakeware made for European consumers is still made with borosilicate glass. Read more here:

  12. Hard sell? What do you mean exactly?

    Interesting, I’ll definetly check out the Pyrex brand you mentioned and have also been almost sold on le cruesset products – until I read somewhere the company doesn’t use good quality cast iron anymore!? Or are manufactured in Asia somewhere!? One of them two…

    Thanks for your replies and help, look forward to hearing from you.

  13. Hi Jay and Irina,

    I do own a few of the MEC pots/pans as well. They used great words in describing their products but I have yet to experience any of the awesome qualities in my food when they are cooked in the clay pots. I also noticed right away the clay taste every time I cook in them. I thought maybe because they’re so new and maybe because I didn’t fully submerge them in water before cooking. I’ve read in other websites that before use you have to fully submerge in water before seasoning–but Miriam’s directions just said to rinse under running water for a few minutes before seasoning. Anyway, I was also very careful with following directions and cooking with wet ingredients only before I use any meats. Finally, after cooking just pasta and brothy meatless soup in my big clay pot, I thought it was seasoned enough to cook a meaty soup. I boiled some chicken in it and the soup tasted pretty good. The clay taste was just a hint this time. Had left overs and had the pot cool down a bit and then I noticed that the pot was perspiring on the bottom with dark brown liquid. My soup was simple chicken based–so nothing brown about it and I only threw in salt, lemon grass, and basil. I decided not to worry too much and then put it in the fridge. Well the next day, I took the pot out and it was leaching because there was a brown puddle in the fridge. It was like as dark as soy sauce but I didn’t use soy sauce and have never used soy sauce in the pot itself. So what could it be? My husband keeps saying that he’s getting less and less impressed with these clay pots. Thank God we haven’t felt sick from using it.
    Also, I have emailed customer service about possibly clay leaching into my food. I have noticed that when I do wash these pots, the water tend to turn slightly brown as in maybe the clay is washing off into the water. If it’s doing that while I’m washing it, then it’s possible that it’s doing that while its being used. CS thought maybe because it wasn’t seasoned enough—-but told her that I used it to cook pasta many times already. The second time I asked questions, CS took over 2 weeks to answer my questions. Wonder if she was trying to ask around for the answer?
    Did you ever find out if the clay pot was leaching out chemicals into your food?

    • Hi SP: thank you so much for sharing! It is so good to know. I had not used the pot for that long so I was interested to learn what can happen with the longer use. I remember that when I was washing the pot, my sponge turned brown. The fact that I saw that and you saw water discoloration leads to believe there is migration/leaching of clay into food. My understanding is that, normally, ceramic cookware has glaze that, while may contain toxic metals, made into an inert material that produces very minimum leaching and thus safer than unglazed clay cookware such as this one. I was not be able to find what the composition of the clay MEC pots are made of. Since clay comes from the earth, it can have a variety of substances, some of which are not good for us, such as aluminum. By the way, MEC pays commissions to bloggers whose favorable reviews you might have read before buying the products. I, on the other hand, recommend only products that I believe are the best. I am glad you found my honest blog. Stay in touch! ~Irina

    • Alexandrovna

      My MEC pan was also perspiring/leaking when I was cooking pea soup with it after properly seasoning it as instructed! This “liquid” was not just plain water that dripped onto stove and evaporated – it kept burning when dripping on the stove and after awhile turning brownish too. The smell of “burnt food” was pretty bad in the house and I kept coughing after that all day (and my lungs felt weird – almost like a mild asthma attack) and I got a bad headache! My husband keeps saying this cannot be normal and how can we return it! Ughh… The thing is – the food IN the pan is not burnt at all – it’s the “liquid” that kept leaking out of pan and burning on the stove (or the outside of the pan) that was smelling so aweful! Wish I read your post before I bought this – starting to regreat it already. The whole house has a clay smell too, even after airing out the house for 1-2 hrs.
      Also, anyone else’s MEC pans/pots constantly produce some sort of fumes (it’s not really a steam from hot water) when cooling with it and even when done cooking with it and taken off the stove?
      Also, did not really care for my pea soup from it – ALL the water was gone. These MEC pots/pans maybe are ok for rice or something, but not for stews or soups – they lose ALL the water!
      Not happy so far!

      • Thank you for sharing, Alexandrovna! MEC products seem to be non-functional. Has anybody tried to get their money back?

  14. I recently bought a MEC pot, which Miriam assume me was perfect for steaming veggies. But after discovering it took forever just to steam a few veggies, having the pot leak, and severely burning my hand on the too short handle of the really crappy Norpro diffuser they recommend, I decided to go a different route.

    I bought the pyroflam (pyrex) 2L steamer set, made in France, from a retailer in
    England. The bottom piece is a round version of your typical squarish rectangular Pyrex baking pan. The top piece is a clear glass steamer basket and lid that fits on the white bottom piece (it also fits on the 9″ Visions saucepan). The glass steamer basket doesn’t hold quite as much as our old stainless steel steamer pot, but we LOVE it. It works well, is easy to clean, and can go in the dishwasher. If you don’t want the full set, they sell just the glass steamer basket separately.
    Since these are not sold in the US, I bought on eBay from a retailer England (roxy_media). The shipping cost was an unbelievable $6 US dollars to ship either the two piece steamer set or the glass basket to the USA!!! In the US, you couldn’t ship the box across town for that price! I was quite pleased with their service. It took 2-3 weeks for the steamer to arrive. Here are the links for the retailer I used:

    If you are looking for a US retailer for the French made Pyrex baking pans, Bed Bath and Beyond can special order these in (if they don’t have it in stock) for no extra charge if you pick it up at the store. The French pyrex baking pans are still made the old way with the borosilicate sand, so they don’t have the problem with exploding like the ones now sold in the US.

    • Thank you for sharing, Joanne, such helpful information! ~Irina

      • There are several websites addressing the inferiority of soda lime glass over borosilicate. When a seller claims a pot is made of borosilicate, how do we know that it is not soda lime glass sold from outside the US? Is there a way to tell apart soda lime glass from borosilicate without relying on a seller?

        Great blog! Very useful.

  15. I’ve been having the exact experience you described with a Vitaclay 2-In-1 Yogurt Maker/Personal Slow Cooker. Bummer!

  16. Can anyone suggest to buy ceramic and coated iron with quality pots from asia specifically india

  17. missjenn

    hi there,

    i’ve also been looking at the vitaclay slow cooker as a clay-based alternative to my good old ceramic rival slow cooker. have you done any digging on vitaclay? i’m very curious about their products. thanks for any insight you have to offer. just discovered and love your blog!

    • Hi, there! I do not recommend Vitaclay. It is similar type of unglazed clay cookware detailed in this post. The composition of the clay is not disclosed and since there is no protective glaze whatever is in clay leaches into your food. I do not see any leaching test report for lead and cadmium required by Prop. 65 on their website. Also, the clay they comes from China. Thanks. ~ Irina

  18. Just a suggestion: Why don’t you just ask Miriam to call the testing lab and permit them give you their test results? Or ask Miriam to send you the test results (instead of trying to your own testing)?

    • Ha Ha Ha This is a common sense. That’s the ridiculousness of the situation. Miriam said that her company’s policy does not allow her to disclose the composition of the clay she uses. So she advised me to call the lab. Then I called her and told her the lab would not disclose. She said nothing helpful. I got rid of the pot. I remember the whole experience with it as a nightmare. ~Irina

  19. Hi guys, I too have a MEC pot. I’ve had it for about 2 years. It’s great for re-heating food, leftovers, cooking veggies, etc. What is is NOT good at is anything liquid based. Don’t try to make soups, tea, or steam anything with it, as that will only result in water leaking out the bottom of the pan, and burning the bottom of the pan. As long as your cooking is not liquid-based, it will do fine.
    If you want a more all around functional cookware that is non-toxic, I’d go with Le Creuset. These are cast iron with a ceramic non toxic glaze. Wonderful. Easy to use.
    Now, if you could do an article about a non-toxic tea kettle, that’d be great! It’s not an easy thing to find. Has anyone researched Staub kettles?

  20. Hi
    Was wondering whether you had come across Tierra Negra, produced in Columbia. ( I’ve been using these for years and haven’t yet found anything else to match. I’ve found the bigger the pot the more fragile and therefore the more likely to crack sooner rather than later. I’ve had smaller pots lasting 5 years plus. Even with a crack they’re still usable until a point where the crack gets too big and seepage occurs. I’m prepared to put up with this for the sake of my health.
    All the best.

  21. I think that the key to using these types of pots is proper seasoning and slow heating. There’s a learning curve to any type of new cookware and (as a home chef who takes the kitchen seriously!) I’m always reluctant to believe accounts on these things when the individual has only used the product a handful of times. It takes a lot of time, skill and knowledge to perfect and understand different cooking apparatus and methods… Overall, I like the info on this blog, but I found this article rather lacking :/

  22. Hi there,
    I have been using earthen pot since last 7 months.I used to saute vegetable in the earthen pots.few weeks after since bought it I found that at every time I heat the earthen pot the oil stains up the pot (oil I have used for the previous cooking)I have tried cleaning the pot 2-3 times after each use to see no change in the condition.I heard of repeted heating of same oil can cause cancer. Could u pls write back for my concerns.

  23. there any hope for toxin free cooking? 🙁 just when you think you are going the healthily route-you end up getting a reality check.

  24. I bought a Miriams (MEC) pot and used it a few times. I thought the food tasted great. However, the food made me feel sick and I recognized the symptoms I was experiencing as the result of glyphosate exposure. The food I cooked in the pot was organic. I had been cooking the exact same food from the exact same source for in a glass pot the weeks prior to getting the MEC pot, so it seems really unlikely that the glyphosate came from the food, as Miriam tried to convince me.
    Miriam said that the clay comes from an area that has not been cultivated in many years and they dig down under the surface to get it. I suspect that’s probably true. However, my doctor recently told me there’s a new study showing that a significant percent of the rain in the USA contains glyphosate (the herbicide used in RoundUp-for GMO and other crops), so it’s raining down on a lot of organic crops and otherwise uncontaminated land. It seems that the clay for the MEC pot may have been contaminated with glyphosate due to rain. I’m not sure how the glyphosate got there, only that the food I cooked in the pot contained it, and the same food cooked in glass did not. Since return was not allowed, I’m stuck with an expensive pot I can’t use. A friend who has one and is not sensitive to herbicides wants it. But I keep thinking, sensitive or not, who would want to eat extra pesticides. This is just my experience.

    • This is the problem. Because there is no barrier/glaze and the pots are not inert, whatever is in the clay (and we do not know the composition of the clay) ends up in the food. Thank you for sharing. What were your symptoms? I wonder if I had the same symptoms. ~Irina

    • Hi Irina,
      Symptoms were a lot of swelling, being wiped out, and extreme weakness in my legs. The leg weakness thing happens every time I get exposed to glyphosate. The other thing to realize is that since there is no glaze barrier, whatever is in the food ends up in the clay. So say you cook some rice, which is known to have arsenic, now do you have arsenic stored in your clay pot ready to get into your next meal? Miriam insisted that if there was glyphosate in my pot, that it got there from cooking glyphosate contaminated food.

  25. Not sure if you have already mentioned it in the above comments and replies, but have you found any issues with glass ceramic sets. We use Visions cookware. Thanks

  26. Hi Irina,
    I’ve got a La Chamba soup pot, which I think is awesome. It’s also unglazed. I don’t have any trouble with leaking liquids or health issues. But of course we’re all different and you never know how someone might react.

  27. Thank you very much for sharing this experience with us!
    What do you think of Xtrema cookware? it is very expensive but the owners say it is the healthiest cookware in the planet and it is 100% ceramic.
    I am really confused whether to go for Xtrema or greenlife cookware?

    • Hi, Ruby: Thank you for asking the questions. You will find your answers about Xtrema here. In short, after I contacted them multiple times and knowing the alternatives, I concluded that it is safe but it requires some adjustment to use it. As for Greenlife, generally, I am wary of ceramic non-stick coating because ultimately they do not know what it is made of. Also, the coating comes off exposing aluminium. For more information, you might be interested in my 7 Days to a Healthier Kitchen e-book. ~Irina

  28. Thank you for your research. My roommate uses pampered chef unglazed stoneware dishes to bake everything. I can’t stand the way they stink up the entire house for a day or two. It’s as if every meal she’s cooked in them comes out while she’s baking food in them. After a Year and a half of her baking and After last night’s chicken I am going to ban them from the house. There’s a weird clay chemical smell as well. I have been not been feeling great either, headaches and low energy and now wonder if the bakeware could be contributing. I honestly don’t get the appeal anyway – glass is great for baking and safe. The porous nature of the clay just doesn’t make sense to me when trying to keep flavors pure and untainted. Plus it’s so tricky to season and maintain them which she does not do- she scrubs them with soap and water as well. Thanks again.

  29. Sterling

    Thanks for your review. I have just recently been researching different cookwares to find one that is best for me, and safest. Never thought of clay cookware.
    The clay smell and taste in my food would be a deal-breaker for me, though.

  30. Isabella

    Hi everyone!
    I’ve been researching healthy cooking pots for a couple of days and keep coming up with Dr Mercola.
    Has anyone tried them or heard of him?
    They’re ceramic and reasonably priced.
    Also he doesn’t charge postage from the US.
    I haven’t bought them yet, just wondering if anyone has any information on them.

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