Mission Impossible: Should you choose to accept this burger (and other bio-engineered foods)?

My Impossible Burger

Palo Alto, CA. October 20, 2018

It was almost lunchtime and I was at Dinah’s Garden Hotel restaurant in Palo Alto on the last day of my visit to California. I had planned to order a late breakfast, but as soon as I saw that the Impossible Burger was on the lunch menu, I knew I had to give it a try.

According to the menu, the Impossible Burger is a “patty made from plant based ingredients; wheat, coconut and potatoes,” and it comes with “Teriyaki sauce, grilled pineapple and coleslaw served on a sesame bun.” What this doesn’t say, although it is not hard to find out, and I knew anyway beforehand, is that a key element of this burger is bio-engineered.

With a bit more detail, here is what the patty is made from, according to the web site of Impossible Foods, the burger’s developer and maker:

Impossible Burger full ingredient list: Water, Textured Wheat Protein, Coconut Oil, Potato Protein, Natural Flavors, 2% or less of: Leghemoglobin (Soy), Yeast Extract, Salt, Konjac Gum, Xanthan Gum, Soy Protein Isolate, Vitamin E, Vitamin C, Thiamin (Vitamin B1), Zinc, Niacin, Vitamin B6, Riboflavin (Vitamin B2), Vitamin B12

The novel key ingredient is soy leghemoglobin. This is the source for heme – a protein which, in animals (and humans), is a constituent of the hemoglobin molecule that contains iron, makes blood red and carries oxygen in the blood. Animal heme gives meat its taste and smell. Importantly, heme is also found in plants. Impossible Foods makes heme by genetically engineering yeast.  As the company says:

“We add the soy leghemoglobin gene to a yeast strain, and grow the yeast via fermentation. Then we isolate the leghemoglobin, or heme, from the yeast. We add heme to the Impossible Burger to give it the intense, meaty flavor, aroma and cooking properties of animal meat.” (Impossible Foods, 2018).

In terms of look, feel and taste, well, this was a surprisingly good burger. It had the look and smell of a grilled beef hamburger, although with a more crumbly texture. Like a “real” hamburger, it had a nice fatty quality and it did bleed a bit red. The taste was good too – I rather liked it. Of course, the various trimmings on the patty all added to the flavor. The restaurant price was $18 — which was similar to the regular burger offers on the menu.

The Impossible Burger promises to be better for the planet. A burger without the cow means avoiding the energy, water, feed, methane and other greenhouse gas consequences of rearing animals. Heme from modified yeast also avoids the release of carbon associated with growing and digging up soy plants, although the burger does use wheat, potato, coconut ingredients derived from conventional agriculture. To the extent that renewable energy is used for fermentation, raw materials sourcing, and transportation, the planet is also better off.

In its own environmental footprint assessment, the company states that the Impossible Burger needs about one-quarter of the water and one twentieth of the land required to produce a conventional cow meat burger, and releases 13% of the CO2 emissions.

And, there is no need to kill animals.

The Impossible Burger’s environmental edge over the familiar cow meat burger is reported in another peer-reviewed study, by Danish researcher Benjamin Goldstein and colleagues. This 2017 study also finds that the Impossible Burger generates more greenhouse gases and uses slightly more water and land than vegetarian and vegan alternatives. (Two of the co-authors of the study are employees of Impossible Foods, as is fully disclosed.)

I wondered, though, is this burger good for your health? The US Food and Drug Administration has found the heme in the Impossible Burger to be “generally recognized as safe,” notwithstanding concerns raised by the Friends of the Earth and others. The Impossible Burger is cholesterol free. Additionally, there are said to be no hormones or antibiotics, and vegetarians will like that it is plant based.

But, in other ways, the Impossible Burger is not greatly different from a conventional beef hamburger. Indeed, the Impossible Burger contains more calories and also reproduces some of the cautions associated with meat. Ounce-for-ounce, there is more saturated fat.  That’s the kind of fat that can raise bad cholesterol. Doctors are recommending us to reduce saturated fat to about 11 to 13 grams per day (that’s a single Impossible Burger!).

The high level of saturated fat in the Impossible Burger derives from the use of coconut oil. The sodium content is also more than 7 times higher than for a regular ground beef patty. A single Impossible Burger could make up nearly one-third of the recommended daily salt intake (1500 mg) – and that is without the dressings and sides. [Below, the source of this information]

Impossible Burger

So, bottom line: The Impossible Burger tastes pretty good, it is animal-free and cholesterol-free, and it seems to be net positive from an environmental view. From a human health perspective, though, it seems we need to watch out for the calories, saturated fat, and high sodium content. It is not gluten-free and contains a fractional amount of soy protein isolate. Perhaps the next generation of engineered burgers will be available in low fat and low-sodium versions?

The mission, should you chose to accept it …

The Impossible Burger is just one of a growing number of bio-engineered foods that are coming onto the market. The roster of start-up companies pioneering these foods include:

And also:

  • Dog food without animal ingredients: Wild Earth (“radically redesigning how we feed our pets”).

Several of these companies pitched at the SynBioBeta 2018 Conference that I recently attended in San Francisco. A common thread in all their pitches was the need for new food production approaches that could feed the world’s burgeoning population in “greener” ways — i.e. without the greenhouse gases, petrochemical fertilizers, and other environmental impacts of industrialized agriculture.

I admired the ambition of these ventures: they really want to disrupt how we eat, not by urging us to become vegetarians and vegans (although that would help) but by making foods that are just like the ones we already consume and which can be produced more ecologically through biological engineering. Yet, the challenges of developing and scaling-up bio-engineered foods are massive. The existing food industry is well-entrenched and, while the Impossible Burger has risen in visibility, public reception still remains uncertain.


In April 2019, it was reported that Burger King would introduce the Impossible Burger in its US outlets. In tests, employees and customer were said to “struggle to differentiate” between the Impossible Burger and a Burger King meat Whopper.

Meanwhile, a competing approach — making “burgers” from plants and using beetroot to make the burger “bleed” — is gaining traction.  Beyond Meat’s “Beyond Burger”  uses no genetically modified organisms, though fully trimmed it has a massive 890 calorie count, according to a BBC post; this company is seeking a share offering that values it at nearly $1.5B.


Goldstein B, Moses R, Sammons N, Birkved M, (2017). Potential to curb the environmental burdens of American beef consumption using a novel plant-based beef substitute. PLoS ONE 12(12): e0189029.

Impossible Foods, 2018. Frequently asked questions. https://impossiblefoods.com/faq (accessed October 29, 2018). Impossible Foods has several patent grants and applications related to heme (see, for example, US9700067B2WO2015038796A3US20150289541A1).

Yu, Christine (2018). Is The Impossible Burger Really Better For You Than A Regular Burger? Women’s Health, June 1.

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