Safe Cookware

A few years ago, I learned about the dangers of some commonly used cookware. However, it took me until a few days ago when I walked into a few supermarkets just out of curiosity, to see what people were commonly buying in terms of cookware. The cheapest option is what average people normally use, because if those are cheap, the average consumer is often not informed enough to be discerning in their purchases and won’t look for healthier, better quality alternatives. However, some cheap options can be safer than expensive ones.

Most items contained aluminum. I was somewhat surprised because I was aware of the various studies in which acidic things would make the aluminum leach into the foods or the beverages, in quantities that are toxic, especially if used daily. Other commonly used toxic metals that can leach from cookware are nickel, cadmium, lead, and iron.

I set out to investigate the available options for safe cookware; comparing the materials used, price point, and general accessibility of the available cookware options. I often saw very expensive cookware sets that were no better than the cheaper options due to the materials used and therefore still likely to cause adverse health effects in the long term.

1) Glass Cookware

I normally use glass pans, Pyrex or Vision, but sometimes use the steel pans without nickel. Although they darken a little when they age, they don’t rust.” Ray Peat, PhD

I’ve never seen Pyrex cookware that could be used on a stovetop, but if you know of any that exists then let me know.

There are some cases of people getting injured by glass cookware, but the only way they can break is cooling them too rapidly from a state of high heat, but they won’t “explode”, they’ll just crack or shatter. I’m inclined to think that the explosion stories were produced by people trying to malign the product, or make money from lawsuits. In any case be careful and follow the instructions!

Everything, including acidic sauces, can be safely cooked in this type of cookware. Vision’s cookware is grand, aesthetic, and you can watch the things through the glass, which is cool.

On the basis of what I know, I consider glass cookware to be the safest option. I use it since a few years; a couple times I dropped a pan or a pot and had to buy it again. You can buy each piece singularly, but I’d recommend the whole 3-pieces set that includes a medium-sized pot (ideal for cooking vegetables, soups, stews, etc.), a frying pan, and a saucepan.

2) Stainless Steal

Risultati immagini per stainless steel cookware

There are various types of stainless steel. Generally, they’re categorized in 18/10, 18/8, and others, including 18/0, that is the interesting one for us. The numbers indicate the amount of chromium and nickel in the metal alloy. You want to avoid nickel like plague. Funnily enough, the 18/0 types are considered the lowest quality ones, and are usually cheaper, in spite of being the safest.

“There are two main types of stainless steel, magnetic and nonmagnetic. The nonmagnetic form has a very high nickel content, and nickel is allergenic and carcinogenic. It is much more toxic than iron or aluminum. You can use a little “refrigerator magnet” to test your pans. The magnet will stick firmly to the safer type of pan.” Ray Peat, PhD

“I think the nickel content should be less than 2%; the magnetic pans are hard to find (used stores sometimes have old ones), because people generally prefer the slick high nickel type.” Ray Peat, PhD (email exchange)

Especially acidic foods will leach nickel from the pans. Several studies and experiments can be found about them, and I’ll link some in the references section.
Stainless steel of the right type (no nickel, or less than 2%), remains a very solid choice and won’t break if you drop it unlike the glass cookware. Even if they’re not very common, there are now some products made with the 18/0 alloy, which doesn’t have nickel.

The magnetic type is free of nickel, and safe. For a time, no one was selling new utensils made of that, but with increasing awareness of nickel toxicity and allergy, lots of people are taking a little magnet with them when they shop for utensils. 430, or 18/0, should be stamped on it somewhere.


3) Cast-iron

Risultati immagini per cast-iron cookware

Cast-iron is another safe choice to cook your foods, however, in this case it would be prudent to avoid cooking acidic foods, including sauces, lemons, etc., because it will react with iron and pull it out of the pan and into the food, and remove the seasoning (the baked-in oil). Proper “seasoning” of cast-iron cookware is something you should read up on if you wish to use it. Generally, cast-iron cookware comes pre-seasoned, but some mistakes can damage the seasoning.

There are many theories about how to handle those pans, but I think it’s safest to avoid soaps or very abrasive items like steel wool.
Some people have reported that leaving a little butter and coconut oil residue on the pan, and just wiping it clean, without washing, has prevented rusting successfully, but I think washing it with water, and then drying the pan in the oven, in order to dry it thoroughly is o.k.

Rusted pans that have lost their seasoning can be recovered, and I’ve spent quite a bit of time researching the topic, looking for some methods that gave me the impression that they had some scientific and chemical background to them. Sheryl Canter’s article is, I think, a science-based, accurate, how to, but I disagree that linseed oil is the only choice. I think canola oil, rapeseed oil, corn oil, and similar oils are o.k. too. Those oils form a varnish that’s very inert, so the polyunsaturated fatty acids are not a problem in this case, but it’s good to be cautious with the smoke that is produced while doing it, because, like any smoke, it’s rich in polycyclic aromatic hydrocarbons that are carcinogenic to inhale.

It’s a bit of a hassle, but I think it’s worth it to recover a good pan, and it can be satisfying if the process turns out successful. It requires numerous thin layers of baked-in oil (about one hour baking each time), after having soaked the pan(s) in a solution of water and vinegar, to remove the rust. As soon as the pan is removed from the solution, it starts to rust again. It’s good to dry it in the oven, and then clean it with the oil to remove the rust that has formed again, then leave an extremely thin layer of oil remaining (basically wiping it with paper towels until you can’t remove any more oil, and there is no more rust on the paper) before you begin to season it. Ideally, it should be seasoned numerous times, until a black opaque varnish is formed. But the article I linked will explain the process more thoroughly.

4) Teflon-coated Pans

I understand that this is a controversial topic, and that it may raise some eyebrows, but I have learned that teflon-coated pans can be safe. They generally contain PTFE (polytetrafluoroethylene), a plastic polymer, that’s extremely inert to heat or acids, so the only way to actually be unsafe while using them is by chipping the teflon coating. Cutting in them would likely cause chipping, so that should be avoided, and leaving them on a red-hot burner too long can damage the teflon, but otherwise I think it’s more a matter of prejudices than real unsafeness. Another good precaution would be to do a first heating without foods, to avoid the risk of some volatile monomers that could still be there after the making.

I have been using those in Mexico, while I’m traveling, because glass is fragile and unpractical, and cast-iron is very heavy. Ceramics in Mexico might still contain lead, so Teflon pans can constitute a cheap and practical option in some circumstances, e.g. when traveling. I have been very happy with their extreme practicality, they are light and easy to wash. I found them well suited to oil-free cooking when I did not have good cooking fat available.

Other options would include ceramics, but I don’t know much about them, so I don’t feel like dedicating a paragraph to them. The only thing I know is that some ceramics are unsafe because they might contain lead, but probably the U.S. and Europe have standards that prohibit the common toxins. In Mexico, and other “developing” countries, they probably have still a lead glaze, and they look shinier than most others.

Although copper pans would be a good way to occasionally get some copper, I have heard they have a negative effect on the taste, giving butter and beef fat a rancid taste, so I haven’t tried them.

Since cookware is something that we interact with pretty much daily, I think it’s good to avoid the toxins that can be released from the utensils, for long-term health and safety, and to avoid the potential degenerative diseases and inflammation those substances promote.

References and recommendes reads:



3. Iron’s Dangers, by Raymond Peat, PhD (contains several references, especially about iron)

4. Chemistry of Cast Iron Seasoning: A Science-Based How-To

3 thoughts on “Safe Cookware

  1. Hello! Are you not worried about iron toxicity? I’d been happily cooking with cast iron until I read Ray Peat’s article about its dangers, now I’m worried the iron will leach into my food and I’ not sure what to fry things in…glad I found your article though 🙂

    1. I am concerned about iron toxicity, or iron leaking from cookware, but if cast-iron is well seasoned the surface varnish is very inert, unless acidic things are used, or if the seasoning is chipped. The bare iron is harmful. Ray Peat does endorse cast-iron under those circumstances, I asked him a few months ago. If you want to be free of any worry, though, glass is the way to go; Vision brand seems to be the only one on the market but as far as I can tell it’s excellent quality, been using them for years now.

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