Tell the FDA: The Impossible Burger’s GMO Heme Should Be Safety-Tested!

Whether you’re excited about new meat alternatives, or you’d rather eat regenerative organic grass-fed beef, we can all agree on one thing: The U.S. Food & Drug Administration (FDA) has a responsibility to ensure that all meat alternatives are safe for consumers.

TAKE ACTION BY SEPTEMBER 3: Tell the U.S. Food & Drug Administration to safety test the GMO Impossible Burger—before the burger is sold to consumers!

hamburger with vegetables on a wooden cutting board

The FDA is about to let consumers become guinea pigs in the Big Impossible Burger GMO Experiment.

Here’s why. The Impossible Burger contains a GMO ingredient called soy leghemoglobin (heme), which the FDA should have regulated as a Food Additive—but didn’t. 

Instead the FDA allowed the ingredient to go through the Generally Recognized As Safe (GRAS) process, which is voluntary. In the GRAS process, the FDA makes no conclusions of its own about an ingredient’s safety. It simply chooses to ask more questions of the company, or not. 

The FDA had a lot of questions for Impossible Foods, the Silicon-Valley-based maker of the Impossible Burger. The agency was especially concerned about the potential of the more than 40 proteins contained within GMO soy leghemoglobin to be allergens. 

The FDA reportedly told Impossible Foods:

“F.D.A. believes the arguments presented, individually and collectively, do not establish the safety of soy leghemoglobin for consumption nor do they point to a general recognition of safety.”

So what happened? This: Impossible Foods responded to the FDA by supplying statements asserting that, based on the company’s own research, the ingredient contained no known allergens or toxins. 

The FDA then ended the GRAS process by sending the company a “no questions” letter.

End of story? We hope not. Now that the FDA has a chance to regulate the Impossible Burger’s GMO heme as a color additive. 

GMOs are lab-created proteins that aren’t found in nature. So they’re not something humans would naturally consume, which means they can expose us to toxins, trigger immune responses or cause digestive problems. (For more on this, watch Robyn O’Brien’s excellent TEDx Talk.)

The only way to safety-test new GMOs is to conduct long-term studies on human volunteers, before the GMOs are released into the market where people can consume them. 

Yet this isn’t required by regulators—even though the few studies that have been conducted on humans show problems, including immune responses, allergic reactions and the transfer of GMO proteins to human gut bacteria.

Without pre-market safety testing, we’ve all become part of the big GMO experiment. In 1989, a dietary supplement, L-tryptophan, produced using genetically modified bacteria, was found to be toxic. L-tryptophan killed 37 people and disabled more than1500 others.

In 2000, StarLink, a variety of genetically modified Bt corn that wasn’t approved for human consumption, accidentally entered the food supply. The corn caused severe allergic reactions, including anaphylactic shock.

In the cases of L-tryptophan and StarLink, regulators were able to trace health disasters back to the specific GMOs that caused them. But it’s been far more difficult to prove that the introduction of GMOs into the food supply has caused a corresponding rise in allergies. 

A recent review found “evidence that genetic modification, in some instances, resulted in the product having decreased IgE binding capacity in subjects with allergy compared with its conventional counterpart, which could indicate hypo-allergenicity.” However, because “there were no animal or human studies identified that evaluated the effect of the consumption of GM products and the overall risk of developing a food allergy or other allergic disease,” that issue remains unsettled.

The Impossible Burger has just one more hoop to jump through: final acceptance of its color additive petition, which will allow the company to sell raw Impossible Burgers in the meat case at grocery stores.

We think the Impossible Burger should be required to undergo rigorous pre-market third-party safety testing, post-market regulatory oversight and mandatory labels. 

The final comment period on the FDA’s color additive process ends on September 3. This may be your last chance to weigh in on the need for real regulation of GMOs.

Sign the Petition


The Impossible Burger’s genetically engineered soy leghemoglobin ingredient (GMO heme) should have been treated as a Food Additive, rather than simply being allowed to go through the Generally Recognized As Safe process. Likewise, the Color Additive process is insufficient to protect food safety and public health.


As we saw in the L-tryptophan scandal, where a dietary supplement produced using genetically modified bacteria turned out to be toxic, killing 37 people and disabling over 1500 others, novel ingredients produced through genetic engineering are inherently dangerous.


Impossible Foods makes heme the same way as the L-tryptophan was made: by taking the genes that code for soy leghemoglobin protein, inserting them into a species of yeast called Pichia pastoris, then feeding the genetically modified yeast sugar and minerals, prompting it to grow, replicate and manufacture heme.


So many things can go wrong with this process. Yet it would be very difficult to detect contamination, before it was too late. In the L-tryptophan incident, the product was greater than 99 percent pure, devoid of DNA, and the toxin was present in less than 0.1 percent of the final marketed product. Nevertheless, it caused disease and death.


Novel foods like GMO heme should be subject to rigorous pre-market third-party safety assessments, post-market regulatory oversight and mandatory labels.


That’s the only way to guarantee their safety.