5 Surprising Health Benefits Of Cooking In Clay Pots

They lock in nutrients, fight bacteria, and make your food taste better.

June 14, 2017
health benefits of clay pot cooking
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For most of my childhood, the only place I had encountered unglazed earthen pots was in the garden. Then one day, when I was 12, my parents ordered Biryani from this new restaurant that had set our locality abuzz. An earthen pot showed up with a saucer tightly affixed to the top by hardened dough that ran over the entire rim. What magic was this? My mother ceremoniously put a knife to the dough to slice through the seal and a heady aroma of cardamom, saffron, basmati rice and lamb filled the room, as if the Biryani had been cooked, right there, in my dining room. From the earthen pot came succulent tender pieces of meat swaddled in such flavor, and perfect fluffy grains of rice, each a microcosm of everything flavorful that had gone into the biryani. 

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It was such an intense experience that it spurred an obsessive fascination with earthen cook pots—From the Indian handi (which I learned was the name for the Biryani pot) to Spanish cazuelas, Moroccan tagines, Japanese donabe, and Chinese clay pots. I visited villages specializing in earthen cook pots, spoke to clay enthusiasts and nutritionists, interrogated distant aunts who cook in unglazed clay, and somehow, ended up throwing pottery on the wheel myself. 

The more I learned, the more I was convinced that unglazed earthen pots not only held the key to food that tasted better, but that was also healthier and friendlier to the environment. I’ve since switched to cooking in unglazed earthen pots. (And here are some of my favorite clay pots to cook with.) Here’s why you should too. 

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health benefits of clay pot cooking
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Your food will taste better

Whether an unglazed earthen pot can add its own flavor to the food that’s cooked in it or not, is a subject of much debate. Earthen pot cultures, chefs and cookbook authors, like Paula Wolfert who introduced America to the Moroccan tagine and is considered the queen of claypot cooking, swear that unglazed clay vessels give food an earthy taste and aroma—what Wolfert calls “goût de terroir, a ‘taste of the earth’.” But food scientists are skeptical about such claims, given that clay, once it’s fired, is known to be relatively inert. 

 

What can’t be denied, though, is that food does indeed taste better when it’s cooked in an unglazed earthen pot. The secret, perhaps, lies in how it conducts heat. Clay, unlike other cookware materials like steel, iron or aluminum, takes a long time to absorb heat. But once it does, it spreads that heat evenly throughout the clay pot body and releases it just as slowly to the food cooking within. This REALLY slow cooking allows for the flavors of a dish to build slowly, for spices to penetrate more deeply, and for meats, even the tough cuts, to break down into succulent pieces, à la Sous-vide cooking, just without the hassles or the high-end price tag. 

Related: 18 Mistakes That Can Ruin Your Cast Iron Pans

A second advantage comes from the unglazed nature of the clay pot. Because clay is in contact with the food as it cooks, the alkaline clay neutralizes the sour or bitter acids in foods like tomato or vinegar, mellowing it and making it taste a little sweeter. There are generations of anecdotal evidence to support this. Kerala, a southern state in India, is famous for its tamarind-based fish curry, a dish that is always cooked in an unglazed earthen pot, whether at a home or a restaurant. The secret, many say, of the famed fish curry is the magical alchemy of the clay pot itself.

the health benefits of clay pot cooking
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Food cooked in clay pots is better for you

Earthenware pots are the most porous of their better known counterparts, Stoneware and Porcelain — What that means is they can soak water up to 5–8 percent of their weight, called absorption rate in geek-speak. This porosity is what makes a clay pot absorb moisture from the food cooking within, and circulate it back, to help the food cook in its own juices. This is perhaps best seen in a Moroccan tagine, a clay pot with a well sealed conical lid. 

 

“As the heat rises within the confines of the tagine creating steam, the moisture from the steam condenses on the lid and runs back into the food below, thus ensuring the dish remains moist during cooking and no nutrients are lost,” explains Penny Smith, a professional potter from Tasmania who has been researching clay pot cooking for more than a decade now. As a result, the eponymous dish cooked within can be prepared with no oil or liquid added, much like being steamed. And because the natural flavor of any food develops more intensely in a clay pot and has more umami, less salt or sugar is required. 

Related: 5 Best Whole Grains For Meal Prep (And Tasty Ways To Eat Them)

The gentle slow heating properties of a clay pot also play a big role in preserving the nutrition inherent in any food. An experiment conducted in a lab in India found that lentils cooked in an unglazed earthen pot retained 100 percent of their micronutrients, while those cooked in a steel pot retained only 30 percent. Another study, published in the Journal of Food Processing and Preservation, reported that pea paste cooked in a clay pot not only had better color and taste than that cooked in an iron pot, it also tested much lower for total starch and total sugar—both of which are anathema to anyone watching their weight or trying to be healthy. (Here are 3 unexpected foods that can send your blood sugar soaring.)

It gets better. Earthenware is usually made with unrefined coarse clay easily found in riverbeds and creeks; clay that is rich in trace elements. Analysis of clays from Africa, Sardinia and California reveals that clay can provide a variety of macro- and trace minerals including calcium, phosphorus, magnesium, iron and zinc, all of which are essential to the wellbeing of the human body. There haven’t been many scientific studies conducted to test this, but it echoes what Ayurveda, the ancient Indian medical system, has long said about clay pots and what many potters believe— that unglazed earthen pots can add beneficial trace minerals to the food as it cooks. 

cooking in clay pots provides health benefits by keeping bacteria at bay
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They keep bacteria at bay

Cooks from the Indian state of Kerala who swear by unglazed earthen pots as the secret of their famed fish curry, believe another surprising thing—fish curry cooked in earthen pots can stay unspoiled at room temperature, sometimes for up to 2 days, even in the hot summer months. Their logic: the dry cold refrigerator air hardens the cooked fish, mutes its exquisite flavor and requires stark temperature changes when re-heating, killing nutrients. Could it really be that earthen pots help preserve food? The first clue comes from the works of Julius Stumpf, a 19th-century German physician and scientist who used clay as a wound disinfectant and a cure for bacterial infections like cholera, and popularized the idea that clay is inhospitable to the growth of certain kinds of bacteria. This idea finds support in a 2011 study on Kimchi fermentation in the International Journal of Food Science & Technology, which found that aerobic and putrefactive bacteria, that cause decomposition and spoilage, greatly decreased when kimchi was fermented in an unglazed earthen pot. 

Related: How To Get Fermented Foods In Your Diet Every Day

A different explanation focuses on far-infrared radiation (FIR), a term for the greater-wavelength heat that emanates from the walls of an earthen pot as it cooks food. It’s the same kind of heat that comes from the rays of the sun, bounces off hot rocks or radiates from glowing charcoal and has been found in preliminary studies to be beneficial to the human body in a host of ailments. All ceramics have the property of emitting FIR radiation depending on their temperature and biomedical researchers have experimented with embedding FIR emitting ceramics into fibers woven into fabric. (Early this year, Under Armour even released a line of athletic recovery sleepwear which is based on these findings). FIR, when used for food processing, has also been found to reduce chlorophyll degradation, preserve nutrients and extend shelf life by killing bacteria and spores—benefits which all await in an unglazed earthen pot. 

clay cooking pots are safe non toxic cookware
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They’re safe, non toxic cookware

The most compelling reason to start cooking in unglazed earthen pots comes from the one thing it doesn’t do—leach harmful metals into your food. (Here are 4 safe alternatives to nonstick Teflon cookware). 

Sure, you’re thinking—but what about lead in clay pots? I’ve heard that’s a concern. 

“If a pot is unglazed, it’s almost impossible to have lead in it,” explains Oscar Garcia, owner of Ancient Cookware, which sources earthen pots from countries around the world. “The reason lead is found in some clay pieces is because lead was used in glazes to make the colors brighter,” a practice that has since seen a decline. There’s a second line of defense though: the FDA, which tests all earthenware imported into the US for lead and cadmium, and requires suppliers, like Garcia, to certify their products. 

Clay pots are also a sustainable type of cookware
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Better for the planet

Beyond being good for just you and your food, unglazed earthen pots hold a lot of promise for the environment. Because they essentially come from soil, they very readily decompose right back into it when you dispose of them, to be completely bio-degradable, unlike teflon pans and steel pots which take up space in Goodwill aisles or fill up landfills. 

Related: Will This Carbon Sucking Machine Save The Planet?

Penny Smith, a professional potter passionate about earthen cook pots, gives the example of Indian clay tea cups, Kulhar, which are inherently sterile, hygienic and made for only one-time use. “After the chai cups are used, they are crushed under foot to become dust again thus ensuring that the potter can keep making more — a sustainable practice that was put into jeopardy with the introduction of plastic chai cups which created a waste problem.” And because of their heat properties, Clay pots keep food warm for up to 5–6 hours just off residual heat from cooking, reducing the need for re-heating and making it an energy efficient option.

Easier to use than you think

The single biggest resistance to cooking with earthenware pots, comes from this idea that their use is fraught with hassles or that they’re too delicate to be used on a gas flame. “Most clay pots are pretty robust,” says Smith, “one just has to respect their individual qualities.” Here’s how to get started with clay pot cooking:

Cure your pot. It all starts with a good cure. This helps to strengthen the clay against thermal shock, store moisture in the porous material, and in some cases, enhance the flavors. Every culture has it’s own method—from soaking in rice water or rubbing with garlic to boiling milk in it or coating with coconut oil and heating—and they all work. The general idea is to have oil or other materials seep into the porous body of the pot. 

From that point on, it’s a go. “You could use it on gas, on electric, on coil and glass. You could put it in the oven. You could even put it in the microwave,” says Garcia. 

Start at a low temperature. You don’t have to soak it in water each time you want to cook something in it. Just start off on a low temperature, let the pot heat gradually and go up to mid-temperatures. “A pot’s fragility comes down to the nature of the clay, the duration of the firing, the way they are made and the differing thickness of the walls of the pots,” explains Smith. Sure there are earthen pots which would crack on a direct gas flame, but there are so many which wouldn’t. The best part, after the first 2–3 uses the pot naturally becomes non-stick.

Wash it by hand. “People will tell you don’t use metal utensils or don’t scrub it hard, but I use metals tools on mine and I scrub the heck out of it,” says Garcia, conspiratorially. “Just make sure you dry it well, so there’s no chance for it to get moldy.” He also cautions against washing your pots in the dishwasher or with strong-smelling, aggressive dishwashing liquid, because it can get into the pores and taint whatever you cook next. 

They don’t last forever. Unglazed earthen pots can easily have a lifespan of 3 to 4 years—Garcia has one that has lasted for 10—after which they’ll start showing small cracks on the bottom. That’s when you know to retire the pot. “They do have a use by date. In the end, they may well crack and become unusable,” admits Smith. “But then you buy another and it becomes a sustainable practice that can keep a tradition going.”

Have I got you convinced? Check out the best nontoxic clay cooking pots for healthy cooking for our clay pot buying guide.