I am frequently asked by email and in the comments section of recipe posts if a pressure cooker to prepare meals or bone broth is a safe way to cook food.
I’m really glad to see that people are using their critical thinking skills and asking these types of questions. This is far preferable to immediately jumping on the bandwagon of a more convenient technology without giving it a second thought.
The equipment and method we choose to cook food definitely have the potential to impact not only the nutritional profile but also overall exposure to toxins.
For example, most health-conscious people pass on Teflon coated cookware and bakeware these days and for good reason – they give off dangerous fumes when heated among other problems. The nonstick aspect, while more convenient, is just not worth the toxin exposure.
I’ve written before about the excessive EMF danger from induction cooking which is why I decided to pass on buying one despite the beneficial aspects of faster, more even cooking and a cooktop that doesn’t get too hot.
I also never turn on my microwave oven even though I have a perfectly good one in my kitchen (they make a great airtight storage cabinet for baked goods though).
What about pressure cookers like the Instant Pot for making bone broth? Wouldn’t they be just fine?
Traditional foods expert Sally Fallon Morell, author of Nourishing Broth, features pressure cooker bone broth recipes in her book even though she herself does not use one.
Let’s take a look at both sides, pro and con.
What is a Pressure Cooker?
French physicist Denis Papin invented pressure cooking in 1679. He discovered how to cook food faster by simply increasing pressure inside the pot. He accomplished this by mechanically sealing the lid. This prevented the steam from escaping during cooking.
The result of increasing pressure is that water boils more slowly. In other words, it takes a higher temperature for steam to be created. This is important because water molecules are an essential component of all foods. Hence, the higher boiling point of water inside a pressure cooker means the heat transfer through the food occurs more rapidly. This reduces cooking time because the liquid water is hotter before it reaches a gaseous state at the boiling point.
If this seems unnatural at first, it really isn’t. Water naturally boils at a lower temperature in the mountains (190 °F/ 88 °C) than at the beach (212 °F/ 100 °C). This is due to the reduced air pressure at high elevations. This is why mountaineers carry oxygen with them on particularly steep climbing expeditions. The air becomes thinner the higher up you go (i.e, lower in pressure).
From a cooking perspective, food naturally takes longer to cook in a mountain lodge versus a beach house simply because the water molecules in the food don’t get as hot before turning to steam which slows down the heat transfer through the food.
A modern pressure cooker uses this basic principle of chemistry to a homemaker’s advantage by increasing the boiling point of water to around 225 °F/ 107 °C), slightly higher than what naturally occurs at sea level. This keeps the water in liquid form at a slightly higher temperature than normal which improves the speed at which the heat transfer through the food occurs via water molecules.
The Pros of Pressure Cooking
We’ve established that pressure cooking is a natural process given that pressure on food while cooking varies considerably around the globe anyway depending on elevation.
But, how does using a pressure cooker effect nutrients since the water is artificially kept in a liquid state at a higher temperature during cooking? Once again, the news is very positive. Here is a quick summary:
- The 1995 study in the journal Plant Foods for Human Nutrition found that Vitamin C and beta carotene in spinach and amaranth were preserved best when pressure cooked versus pan cooking (1).
- A more recent study in 2007 in the Journal of Food Science found that pressure cooked broccoli retained 90% of the Vitamin C. Steaming only retained 78% and boiling 68% (2).
- A 1994 study published in the journal Plant Foods for Human Nutrition, discovered that the antinutrient phytic acid which blocks mineral absorption in the digestive tract was reduced 54% in peas soaked and then pressure cooked versus peas that were soaked and then boiled (29% reduction) (3).
My friend Kristen has written this excellent article that summarizes the effects of a pressure cooker on food if you’d like to learn more.
The Pressure Cooker Problems that Won’t Go Away
While there are so many positives on the use of a pressure cooker and the science seems solid that using one is beneficial to the cooking process as compared with regular stovetop cooking, I still choose not to use one.
First of all, most pressure cookers that I’ve examined are made of stainless steel. The heavy metal leaching dangers of cooking acidic foods in stainless steel cookware is very real. I wanted an appliance that I could cook any food in – acidic or not. This is why I chose a Vita-Clay (I actually own two!).
More Glutamine?
Secondly, I passed on a pressure cooker because I have not found conclusive research that refutes my concern that pressure cooking may, in fact, dramatically increase the glutamine in cooked foods, most particularly the potential for MSG in bone broth.
Glutamine is a conditionally essential amino acid that is critical for gut, brain and immune health. It is found naturally in healthy foods and should theoretically not be a problem in normal metabolic situations.
The problem develops when glutamine gets past the blood-brain barrier and is metabolized to glutamate. In healthy individuals, this process is tightly controlled by the body. Glutamine is supposed to convert as needed to either glutamate, which can excite neurons, or to GABA, which has a calming effect.
Glutamine is not MSG
MSG differs from glutamate by a single sodium atom attached to the molecule. MSG is widely added to processed, packaged and fast foods in order “wake up” flavors. The truth is that removing the MSG from processed foods makes them tasteless and unappealing. This is why food manufacturers hide it on ingredient lists under aliases such as yeast extract, natural flavorings, hydrolyzed protein, protein isolates, and spices. There are up to 50 MSG aliases used by food manufacturers, with new ones being constantly created to stay ahead of the consumer.
Some of the MSG in processed foods is artificially added, but much of it is actually a residue of hydrolyzing and other modern and rather violent processing methods which means it won’t appear on the label. Protein powder is a notorious offender. Don’t be fooled because products labeled with the words “No MSG” may actually still contain it (4).
As a result of so much MSG in the food supply, many people have become overly sensitive to it to the point where even the natural glutamine in traditional foods like bone broth can trigger headaches (most common symptom), gastrointestinal upset, fatigue or other problems.
Glutamine Levels in Pressure-Cooked Bone Broth
The solution to the sensitivity some folks have to the glutamines in properly cooked bone broth is to start out with a lightly cooked bone broth, progressing over time to the more nutritious, long-cooked bone broths. The glutamine content of broth increases with cooking time as do the levels of other amino acids. Thus long-cooked bone broth is more nutrient-rich and preferable for those who can tolerate it.
The glutamine levels in pressure cooker bone broth are as yet unknown. In addition, how pressure cooking affects the nutrients in bone broth is also up in the air. Here’s what Kaayla Daniel Ph.D., co-author of Nourishing Broth has to say about the effect of a pressure cooker on the nutrients in bone broth:
Neither Sally nor I use a pressure cooker, but we know many people who love them. Pressure cookers seem to help achieve the gelatin we value so much. In terms of nutritional value, we have not done comparison testing of pressure cooker broth vs stockpot vs slow cooker. We’d love to do lab testing for a long lists of nutrients, but that gets very expensive very fast. If you know anyone who’d like to give us about $20,000 for a small study, we’d like to move forward with that testing. In the meantime, I see no reason for you to stop using your pressure cooker. However, we do question pressure cooking for 5 hours. I think most recipes say 1 hour though I’ve seen some recipes that recommend up to 3 hours (5).
Should You Use a Pressure Cooker or Not?
The bottom line is that if you love your pressure cooker and want to use it to make bone broth and other foods, then do it. Pressure cooked bone broth is certainly better than no bone broth. So, if the time savings for you is such that it’s pressure cooking or nothing, then stick with your pressure cooker.
However, if you are like me and prefer a gently gurgling traditional clay pot with no leaching issues over a pressure cooker, then have at it! Until a specific study is done to comparatively test the nutrients, heavy metals, and glutamines in pressure cooked broth, then stay with the tried and true for the time being.
As more information and research becomes available on pressure cookers and the effects on bone broth, I will keep you all informed.
Becky, so glad you brought this up. I read some time ago that pressure cookers change the molecular structure of proteins and should be avoided for this reason. But a recent search only brings up the benefits of using a pressure cooker – the instapot pressure cooker seems to have effectively buried any negative articles. Savvy marketing if you ask me.
Hey, Sarah! Thank you for this article! I’m not sure I got some of your points correct, so can you please clarify the following:
For example I have a multicooker with a function of pressure cooking. There is a ceramic container, but the top of the cap inside is stainless steel (well, it seems that is stainless steel.
If I cook some acid food (e.g. tomatoes or something with vinegar, etc) does it mean that my multicooker (in the case when it cooks with the pressure) can increase MSG in the food?
Basically, I’m thinking about to buy just a multicooker (which can not cook with a pressure) or the one with a function of cooking with the pressure. So, which one will you recommend? Which one will make healthier food?
Interesting! My pressure cooker is producing MSG! I’ve always had a problem with MSG. I first really started noticing problems with it in my early 20s. Then, by my 50th year, now 54, I began to be affected by MSG in extream life-threatening ways. For those wondering about MGS effects and maybe trying to figure out what’s wrong with them I’ll give a brief rundown of the symptoms I have had and then I’ll explain what’s happening with my pressure cooker. In my early 20s, it was just your typical Chinese restaurant syndrome. An hour after eating something with large quantities of MSG I would feel exactly like having a hangover. The kind one gets after a night of heavy alcohol consumption. This was inconvenient, but not inconvenient enough for me to take affirmative steps to avoid MSG. Then, about 30 years later I had lima beans and smoked ham hocks. Right in the middle of eating my second serving, it felt as though a golf ball was stuck in the bottom of my esophagus! And with 10 minutes of that feeling, I felt like I was going to pass out. This very strong feeling of feeling like I was going to pass out last for about 12 hours. It is the most horrible torturous feeling I could have ever imagined! Along with this was a fast pounding heart and involuntary heavy breathing and a feeling of wanting to burb but not able to burp. Also, I had vomiting and diarrhea and very high blood pressure. And then, after the 10 to 12 hours of feeling like I’m going to die any second the symptoms subsided. What I felt then, the next day, was as if someone took a knife and stabbed me all along my colon and parts of my small intestine too. By the third day, I was feeling ok but then another effect came into play and that was EXTREAM ANXIETY AND PANIC ATTACKS! This extream anxiety lasted for about 2 to 2 1/2 weeks!
At the time I didn’t know what was wrong with me and because I didn’t have medical insurance I didn’t go to an emergency room. Well, I did have a friend take me but I decided that I wasn’t going to die since by that time I was feeling ever so slightly better and so I didn’t go in. Over about a year and a half, I had the aforementioned events hit me three times. The third time I was hit so hard that I literally decided to die and so I just let go to die but I didn’t die. 🙂 During that year and a half time frame I was hit by lesser events and was having varying degrees of anxiety and panic attacks. I never went to the doctor because I knew it had something to do with food so I knew I could figure it out and I also still didn’t have insurance. Thinking I had some kind of version of celiacs disease I tried going on a gluten-free diet for about a year and that helped a lot because that directed me away from a lot of processed foods and so I was eating whole foods quite a bit. However, I was still running into MSG every now and then so it was an extream puzzle to me. Eventually, I stopped eating and drinking! And when I would get so hungry I couldn’t stand it I would eat just rice and water. I lost around 60 pounds and I was super skinny and my good friends thought I had some strange disease and was going to die soon. BUT I FELT WONDERFUL!! 😀 So, over a period of a few weeks, I started adding things to the rice. First cilantro. Then Bertolli extra light tasting olive oil. Then pairs and bananas and so on. And so I was eating regularly and gaining my weight back and feeling great. And then I tried eating a stew my dad had made because I thought, it can’t be that bad, just potatoes, carrots, onion, beef, and zucchini. So, I just ate a small amount to see if it was ok. Well, I got sick. Not as sick as the three times when I felt like I was dying but sick enough to know that whatever was in that stew was making me sick. That’s when I dug the empty seasoning packet out of the trash and my eyes went right to the words, “No MSG*” Flipping it over to see what the asterisk meant, it read, “* EXCEPT THOSE NATURALLY OCCURRING GLUTIMATES” That was it! MSG was the substance causing me all the problems! So, I simply learned how to avoid MSG in my diet and I returned to being 100% healthy. Yes, learn! As Sarah touched on, you simply can’t just look for the ingredient monosodium glutamate on an ingredient label, because it has numerous disguised names.
Every once in a while though I’ll run into it in spite of my efforts to avoid it. Like Sarah stated it may not be listed on an ingredient label while still having significant quantities of it. Also, I’ve found that my pressure cooker can make it. I haven’t learned about the chemistry yet but when I have cooked chicken breasts and also beef pot roast there is enough MSG generated to affect me mildly. Some kind of chemical reaction is happening in the meat due to the high pressure. I have never had it happen to a high enough degree to affect me by cooking meats using conventional methods, just when using my Insta Pot pressure cooker. I was just now looking into this and came across Sarah’s article here touching on the subject.
I think you are on to something. Lately every time i eat meat cooked in my Instapot i get stomach aches and digestive issues. I know from having affects years ago eating MSG as well. One has to listen to their bodies. Wonder if all foods cooked in the pressure cooker Produce msg?
That very well could be. I don’t use a pressure cooker because I feel there just isn’t enough data to support it. Convenience always has a price in my experience. That said, if its use a pressure cooker or do takeout, definitely use the pressure cooker! Everyone has a different challenge in getting homecooked, whole food fare on the table, so do what works. I find that there is almost the same convenience with little increase in time required by using a Vita-Clay slow cooker.
I would love to know how pressure cookers impact meat. My daughter thinks it messes up the protein. Is that so?
Amazing post. Liked it most. Waiting for your next article. Best wishes for you.
Just want to correct you on a couple points you made.
Hard anodize is ptfe (teflon) free. And microwaves do not leak out. They are safer to stand near than your cell phone.
This research in this blog post is best summed up as not a solution but, that more research still needs to be done.
Since I don’t like to be a guinea pig, I will continue to skip the microwaves and teflon thank you very much until that “more research” is done! I’ve never understood why some folks insist on exposing themselves unnecessarily to danger … by the time that “more research” is done, your goose may be cooked (literally)! 🙂
I want a pressure cooker to make our old hens and roosters edible. My husband doesn’t want me to get one because of the stainless steel, but isn’t there a danger of lead contamination / leaching in ceramic pots such as the Vita-Clay? If not cooking with acidic liquids wouldn’t leaching from stainless steel be minimal?
The clay used to make Vita-Clay is tested for purity. Check the website for certifications.
Stainless steel is fine if not cooking acidic foods or liquids.
I use a Presto 6-qt pressure cooker (that I’ve owned and used for 40 years with two lid gasket replacements, one over-pressure gasket replacement, and one pressure regulator replacement) for bone broth (30 minutes with natural pressure drop) and artichokes (10 minutes and cold-tap-water-assisted pressure drop), probably because that is what I grew up with. What I have learned to do differently with the bone broth is (1) use the bones over multiple times (10–12 or so), (2) add over-strong kombucha (homemade) to the water (1 Tbsp/cup water) and let sit overnight, and (3) strain the broth off into an open saucepan in which I cook it down to about half volume for richer flavor and more gel. However, having read this article and the linked article by Kristen (Food Renegade), I’m looking forward to making more use of my pressure cooker. I may also try cooking the bone broth longer in the pressure cooker to see if it cooks down enough that way.
Question: What is the issue with bone broth surface “scum”? Does it contain toxins or anti-nutrients or is it simply an aesthetic issue?
The scum that comes to the top when the bone broth is first brought to a boil contains off flavors and impurities. You see a lot less scum if the chicken or beef bones are organic, for example. It makes the broth healthier and tastier if they are removed before the temperature is reduced to a simmer.
such a punch in the stomach.. I am a few years in to a raw milk/grass fed/fermented/bone broth kind of lifestyle….doing the best I can to nourish my children – and your website has helped a lot!
but – it’s so frustrating when those who write and publish in this community, like yourself, depict perfection. It can be a turn off and make me feel like giving up on all the hours I spend in the kitchen. Bone broth in my instant pot has freed up many hours and I don’t know if I’d be making it if it weren’t for 90 minutes in the instant pot. There are some of using doing the best we can and these types of posts are infuriating.. you’d seem much more real and relate-able if you’d write about some of your downfalls, this blog is turning out to be too perfect for me.
Did you read the article … ? I said that if the pressure cooker is what you need to make it work for your situation, then use it 🙂 None of us ever achieve perfection, including me, so if that is what you are getting from this blog, I would read more closely as that is not what is being put out here. What is being put out is information for you to consider and use as you see fit … your choice. No pressure. Whatever you want to do is totally fine.
no, I did not read the article word for word. I succumbed to click bait on fb and only scanned. I felt this came off as a scare tactic. I understand my original comment is slightly out of line considering I didn’t thoroughly read the article..
I just don’t like posts that highlight the worst of the best… stuff like this or .. “are green smoothies really good for you”… click bait.
I can see how some people (perfectionists) appreciate this type of post though.
This article is a pro and con of pressure cookers … very equally discussed. I give my opinion and what I choose to do personally at the end. If you choose to do differently, that is of course fine! There is no click-bait aspect whatsoever to this post nor was it intended for perfectionist personalities of which I most definitely am not.
Personally I’d rather you give me the facts or as many as you know and make your best recommendation than make me feel better with justification and imperfection. Perfection is the goal. I’d rather shoot for the sun and hit the mountain than shoot for the mountain and hit the rocks! I only use a pressure canner for canning meats. Cause other than freezing it there is no way to preserve it. I subject my grass fed humanely slaughtered beef to the pressure canner with all is uncertainty cause I have to. But not my everyday foods where I can choose. And I cook fresh almost every day.
Great article! I have never used a pressure cooker for cooking food but a few years ago I did buy a large one for home canning and never thought about any negative effects other then I think their processing times are extreme! The first time I mad a batch of veggie soup, put in jars then pressure cooker to seal them, my soup ended up mushy! Yuck! The flavor was there but who likes over cooked veggies! From that day on I only cold pack my veggies. I have been home canning with a boiling water bath for over 30 years but my books say if you are going to can meats to use a pressure cooker. I do love the fact that I can do 20 pints in about 2 hours (only 50 minutes or so is timed) verses doing 7 pints in 2 hours with boiling water baths!!!
I also use the pressure cooker to can my bone broth! I roast two chickens at a time and save the bones in the freezer until I have about 8 of them. Then I get my large stock pot out and proceed to make my bone broth stock with the addition of egg shells according to Dr. David Williams for the hyaluronic acid, glucosamine and condroitin.
So I was wondering if the MSG still increases during canning as well or is it just during the cooking process? I’m not sensitive to anything and have not had any problems with anything I’ve canned so far!