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I ate an Impossible Burger – wish I hadn’t

A few days ago at a promotional event, I had the chance to sample an Impossible Burger, the popular Vegan “hamburger” whose mission is to make meat obsolete by 2035. Initially, I was impressed by the resemblance of a plant based burger to an actual burger, however, after I learned the ingredients they use to make Impossible Burgers, I regretted my decision to partake in this burger coups d’état.

But before I get into a discussion of why eating Impossible Burgers is probably bad for you, I do want to give them some props because I believe their heart is in the right place.

The Impossible Burger is environmentally friendly, that much cannot be disputed. Raising cattle the way we do does real damage to our planet, and it has to stop, at least at its current trajectory. The industrial farming system is unsustainable, environmentally ruinous, and cruel to both animals and humans alike which means plant based alternatives to animal foods will be a must in the years to come. Companies like Impossible Foods that create tasty plant based comfort food are badly needed.

I just wish they hadn’t made their plant based salvation burger with gross ingredients, common food allergens, and Frankenstein yeast byproducts.

Just because it’s made of plants doesn’t mean it’s good for you.

Impossible burger designed to look like real burger

As I allude to above, the Impossible Burger is designed to look and taste just like a real burger. This means the inventors were challenged to use plant matter to make a moist, “bloody” patty, with the same texture as real meat. To be fair, I must admit the Impossible Burger is reminiscent of a real burger, it has a texture and color that looks like ground beef, the problem is it uses truly gross ingredients to get there, ingredients that could be just as bad for people’s health as eating a real burger every now and again.

In fact, there was some controversy as to whether the FDA would even approve the ingredient, called soy leghemoglobin, that makes the Impossible Burger “bleed.” Soy leghemoglobin releases a protein called heme which gives the burger it’s meat like traits.

The FDA was was concerned about soy leghemoglobin, because well, it’s never been consumed by humans!

Seems reasonable to me, and keep in mind, this is coming from an organization that has zero qualms about high fructose corn syrup and genetically modified crops, so it’s not like there is a high bar to get the FDA’s blessing.

Genetically modified ingredients

So, to make this soy concoction, the Impossible Burger folks must be ripping through a ton of soybeans, right? No! They get their Frankenstein soy from yeast. According to this Wired Article, “one acre of soybeans yields just a kilogram of soy leghemoglobin,” so the Impossible Burger team created a workaround.

It’s hilariously complex, but Wired does a good job of summing up the process:

Technicians take genes that code for the soy leghemoglobin protein and insert them into a species of yeast called Pichia pastoris. They then feed the modified yeast sugar and minerals, prompting it to grow and replicate and manufacture heme with a fraction of the footprint of field-grown soy.

Ok, so we aren’t even eating soy from soybeans, we’re eating a soy / yeast byproduct combination made from soy leghemoglobin genes?

The first thing I thought of when I read about the yeast’s role in creating the Impossible Burger is what do these yeast derived proteins do to the microbiome?

We don’t know.

Further, the heme protein isn’t the only protein the yeast make. They make 40 others, all of which end up in the Impossible Burger. Who knows what these additional proteins do in the human body.

On their FAQ page, under the question “do you produce heme by genetic modification?” the Impossible Burger team answers a simple “Yes.”

Case closed if you’re not a GMO person.

Safe in rats – what about people?

At this point, you may be saying “John what do you know, you’re just some startup guy, not even a nutritionist. Bill Gates is backing the Impossible Burger, so this soy stuff they’re getting from yeast must be safe.”

Possibly, possibly not.

Is soy leghemoglobin safe?

No one knows for sure, and the answer likely varies from person to person, however, the Impossible Burger team did feed unbelievable amounts of soy leghemoglobin to rats and found there were no adverse effects over a 28 day period. (R) We don’t have studies in humans to see how people will react to the ingredients in the Impossible Burger.

Then there’s the Gluten

But it’s not just the Frankenstein soy that raises red flags, it’s the wheat. The Impossible Burger isn’t gluten free, which means that it is off limits for the growing number of people with gluten sensitivity or celiac disease.

The second ingredient in the burger, after water, is Textured Wheat Protein.

Whole foods plant based?

The scions of the plant based movement, the T. Colin Campbell’s and Caldwell B. Esselstyn’s of the world, are advocates of a whole foods, plant based diet, not a processed foods plant based diet. The idea is that mother nature knows best, we do better the closer we get to consuming whole plant foods. While it is 100% Vegan, the Impossible Burger strays pretty far from this ideal. Creating genetically modified soy proteins in a test tube is a far cry from a macrobiotic plate. While some may do just fine with Impossible Burgers as a staple, I think it’s fair to assume that many individuals will be sensitive to soy leghemoglobin. After all, soy is one of the most notorious food allergens and humans have never consumed this particular soy preparation. Maybe it’s just me, but I’d much rather eat a plant based burger made to “bleed” with beets rather than genetically modified soy.

When will we learn?

In closing, I want to emphasize again that I admire the mission, as well as the ambition, of the Impossible Burger team. Kudos to them for trying to tackle such a big problem.

However, in their quest to make a plant based burger to rival the traditional burger, they overlooked a basic principle of the plant based movement: that the food supply is making people sick.

Consuming large amounts of factory meat has caused Americans to develop a host of chronic diseases, but so has the rise of GMO crops and the use of pesticides like glyphosate. Many people develop autoimmune conditions when faced with the intestinal permeability that is a hallmark of eating wheat, GMO produce and processed foods.

So, yes, make a plant burger, just next time make it with actual plants.

Image credit – Eater San Francisco.

John O'Connor

John O'Connor is the founder of Gene Food and an Integrative Health Coach, trained at Duke IM. He lives in Austin, Texas.

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  1. jak says:

    this is utterly insane. it’s the exact same molecule as heme found in actual meat which is completely safe. how it’s produced doesn’t matter at all. that being said, the impossible burger is also disgusting. the aftertaste is awful.

  2. Lisa says:

    I just ate half an impossible burger and had to stop because of the immediate allergic reaction; hot, intense flushing (almost purple) of my face. I found this post after googling “adverse reactions to food additive gene.” In addition, to other articles, this post helped me to confirm that I was reacting to heme, I went to speak with the good vendor and they were completely misled about the ingredients and how they were produced. They thought the product was completely organic and that all ingredients were “naturally produced and occurring in nature.”

    • Alyssa says:

      Just as a reminder, there is heme in your own body. If you were allergic to it, you could not carry oxygen, and you would be dead.

      • Just as a reminder, but leghemoglobin, hemoglobin and myoglobin are not the same thing! They might all function to bind oxygen but they do all have a different structure. They are different proteins and people could be allergic to leghemoglobin, although it is thought to be not very immunogenic (i.e. it is unlikely to cause an immune response).

  3. Alyssa says:

    As a reminder: 1. Many foods we regularly consume contain live and dead forms of yeast (baker’s yeast in baked goods and bread, yogurt, alcohols, nutritional yeast). When one consumes these foods you are consuming THOUSANDS of yeast derived proteins…. There is absolutely nothing wrong with eating yeast. 2. Any yeast that is used in food production is NOT a pathogenic species of yeast. The yeast used to make this soy protein is not the same species as Canida albicans. 3. Yeast proteins in the diet do not cause Candida Albicans infections or contribute to them. Yeast thrive on sugars and their metabolic breakdown products, not on other yeast proteins. 4. As Jak mentioned above, the soy protein you mention is going to be in the exact same form in a yeast cell as it would be in the soy bean. If the gene originally came from a soy plant, then the DNA is exactly the same, which is transcribed into exactly the same RNA, and translated into exactly the same sequence of amino acids that make up the soy protein. Scientific research consistently uses yeast as a model organism to study basic cell processes, such as DNA repair, and scientist express human versions of proteins in the yeast, where they function exactly as they do in human cells ( This soy leghemoglobin would be no exception. 5. Additionally, millions of type-1 diabetic patients take insulin that is produced in yeast and bacteria, and they are not all dying from candida albicans infections: (this is just one example)

    • Hey Alyssa, thank you for the thoughtful comment. Yes, the yeast used to make this protein is not the same species as Candida albicans, I wasn’t saying it was. I was wondering out loud whether the GMO yeast byproduct (plus wheat protein) used to make the Impossible Burger feeds Candida and other pathogenic species of bacteria and fungus in the gut. I’m not talking about systemic Candidiasis that could threaten someone’s life, but rather gut dysbiosis, which decreases quality of life. However, it’s funny you mention type 1 diabetics as they commonly have yeast infections! There is a long standing connection between diabetes and Candida albicans specifically.

      See also:

      We know that the foods we eat can alter the makeup of the microbiome in as little as two days. What is the impact on the gut of eating GMO soy yeast byproduct combined with wheat protein and Konjac gum? Not sure we know. Also, the Burger is just gross, so there’s that.

      • Alyssa says:

        John, could you please explain to me what this “GMO yeast soy byproduct” is if it is not the soy leghemoglobin mentioned above in the article and me comment. And then please explain to me how it is potentially harmful compared to eating yeast themselves as I mentioned above. And please explain why you think GMOs are harmful to health to begin with, because to my knowledge they do not harm human health (the environment and financial success of farmers is another story).

        • I never said eating yeast was harmful. However, Pichia pastoris has not previously been used to make human food, which Impossible Foods note in their paper:

          As far as GMOs are concerned, I usually avoid them because they have been sprayed with carcinogenic pesticides, however, your statement that the soy protein will be in the exact same form in an Impossible Burger as in a soybean is not true. We looked into this and the reason they use yeast is that leghemoglobin is a relatively complex protein that needs additional processing after it is made. Bacterial systems can’t do this so they use yeast. But yeast systems are different to plant systems and do induce differences. For example P. pastoris has been shown to introduce extra changes to the protein which can generate an immune response:

          To quote Impossible foods:

          “Seventeen P. pastoris proteins, normally expressed by the yeast host, that remain as minor components in the highly enriched LegHb protein product, were identified by Impossible Foods and the UC Davis Genome center using proteomic analysis. Each Pichia protein is present at concentrations of less than 0.1% in the plant‐based meat product.”

          “Impossible Foods synthesized the LegHb c2 gene from the soybean plant, inserted the gene into a yeast host, Pichia pastoris (now reclassified as Komagataella phaffii), and purified the LegHb protein expressed in the resulting Pichia strain to >65% purity.

          so there is plenty of stuff in there that isn’t the protein of interest and we have no clue what eating that stuff does to the microbiome.

  4. Alyssa says:

    Additionally, as founder of a company and website aimed at improving health through nutrition and genetics (an idea I think is wonderful if properly executed) you should not be “wondering out loud” and inciting fear in you readers if you do not explain any credible science backing up your imigaination.

  5. Lisa Ratcliff says:

    Thanks John me and my husband Phil stopped off at fatburgers and order the impossible burger, after eating them we began to experience stomach aches, heart burn, and feeling like crap. I guess the name imposible burger should have made my better judgement kick it that it was to good to be true, I must admit like most foods that are bad for you it, taste good going down until it starts coming up again… warning the imposible burger is just another way to scam people like us! who are looking for healthy alternatives. It’s worse than eating hotdogs! My last hotdog was in 1996 and today was my last imposible burger🤪

  6. Mary says:

    I’m vegan and I ate the Impossible Burger three days ago and I’m still paying for it. My husband said I might have to see my doctor as I am still having terrible gut issues and can’t pass any food normally yet with awful pain in my gut. I don’t know if it’s an allergic reaction or yeast buildup but I can’t continue this way. I’m so angry that the company is allowed to sell this gmo crap! I’m just hoping I fully recover from it soon.

  7. Rheologist says:

    One needs to be really crazy to eat something named “impossible” it is just s challlenge to people’s ego and their “ wisdom” ?
    When it comes to foods, bottomline FDA does NOT approve anything, all they do is to issue a Letter of no objection””
    Yes, it us GMO,.
    Where is Proposition 65 position in this ?
    The main issue is not the makers of the “IMPOSSIBLE “ burger, it is the consumers that consume it ! Do rhey read the label? Do they research and make a wise decision about how to protect their bodies? Or is it a fashion statement?
    Since I read the book ONE by Fer Na, i just can’t understand the kind of “unconscious “ suicidal behavior people have by not reading the labels if what they eat.

  8. Anonymouse123 says:

    The impossible burger is amazing. I ate two per day for almost a year now, and it raised my b vitamin level and red blood cell count to normal when it used to be low from being vegetarian without eating much B. The impossible burger makes me feel incredible like I’ve just been shot with B vitamins. It tastes just like meat but no cholesterol and no animals dying. I don’t have a gluten allergy so I say bring on the gluten and bring on the Heme that makes it taste like meat. I’m sorry but beets do NOT taste like meat. So that’s why I don’t like the beyond burger as much as the impossible burger. Texture, smell, amd everything is far better on the impossible burger. I am alive and have been to the doctor twice this year for a checkup and to run the numbers. It was truly astounding how much healthier I became from eating the impossible burger. Call me the lab test for humans. I’ve eaten more of it than they would give me in an experiment. So here os your living proof that the burger is Grade A Awesome and has zero side effects for the average person…unless addiction is a side effect. I am obsessed with this burger. I’m basically on a personal mission to find the best one. I’ve had it as burgers, tacos, meatballs and spaghetti, and over mashed potatoes in a sage butter sauce. I wish more restaurants would try different ways of cooking with it. That way, I won’t be bored with having the same thing all the time. Btw, my meat eating family said it was better than an in n out burger.

  9. don jose says:

    I could have saved them 80 million dollars. My wife and I own a very successful vegetarian and organic take out restaurant. Food companies have tried to sell us meat substitute products for years and they all fail for the same reason – vegetarians and especially vegans DON’T WANT ANYTHING THAT TASTES OR LOOKS LIKE MEAT! It’s like telling a kid that hates broccoli that it’s not really broccoli – it just looks and tastes like it. Let me save you even more money – expensive campaigns to write fake reviews and flood social media with how great it is won’t work. You missed the most basic fundamental point – meat eaters want meat and vegetarians don’t. Why is that so hard?

  10. Bill from Texas says:

    This is simple. If you are interested in saving the planet, try Impossible burger 2.0. If it doesn´t taste good or makes you sick, stop! How difficult is that? “Better a diamond with a flaw than a pebble without.” — Confucius,

  11. Bobby says:

    I am 100% vegan. So is my wife. So what’s my 19 year old daughter. All of us enjoy an impossible burger from time to time; sometimes a beyond burger. None of us have ever had any type of reaction. None of what I read in this article is based in science.

  12. Liz says:

    I ordered the meatless burger tonight from A & W and I had very immediate reactions. My stomach bloated out like I was 5 months pregnant, I became ill, stabbing stomach pain and have been experiencing constant diarrhea. I feel absolutely terrible and will never consume this product again. I will be contacting the company as this is not safe for customers to be consuming. No food should produce these results and I have eaten Harvey’s veggie burgers for years so it’s something specific in this product. Absolutely disgusted.

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