The maker of the Impossible Burger tested its secret sauce in rats. Then PETA went on the attack

Is the death of 188 lab rats justifiable if it spares the lives of millions of cows?

That’s the question animating a heated war of words between two organizations that share a core value: saving the lives of animals.

On one side is Impossible Foods, the Silicon Valley company behind the Impossible Burger and other meatless products that actually taste like meat. The company wants to get more people to eat its burger instead of the usual kind, and, in so doing, spare the lives of countless cows that would otherwise be slaughtered for beef.

The animals rights activist group PETA, short for People for the Ethical Treatment of Animals, might be expected to support that effort. Instead, PETA has become Impossible Foods’ most unlikely adversary, pillorying the company online in recent days.

“They mobilized trolls in an attempt to intimidate Impossible Foods and its supporters on social media, bombarded our employees with thousands of auto-generated complaint emails, and tried to disrupt and damage our business,” Impossible wrote in a blog post about the uproar.

So, what happened?

PETA takes issue with several rat experiments that Impossible Foods conducted to test an ingredient in its products.

Part of the reason that the Impossible Burger tastes like beef is because of the secret sauce used to make it: an ingredient called soy leghemoglobin. It’s a protein that contains the molecule heme, which is found in actual meat. By synthesizing heme from the roots of soybean plants, Impossible Foods aims to trick the palate and emulate that burger flavor.

The company has for several years sold its products containing the ingredient in restaurants all over the country, and it didn’t need the permission of the Food and Drug Administration to do that. But Impossible Foods wanted to broaden its reach to larger restaurants and grocery stores, so it decided to seek a stamp of approval from the FDA to try to demonstrate that its product is safe to eat.

Impossible Foods’ initial effort to do that backfired. The FDA concluded the company’s evidence didn’t pass muster, expressing concern that the ingredient had never been consumed by humans and could potentially be an allergen, according to correspondence reported on last summer by the New York Times.

The company determined that it would have to test its special ingredient in animal models in order to get the stamp of approval it wanted from the FDA. So it did so, on a total of 188 rats in three separate experiments. As is typical in medical research, the rats were sacrificed.

Impossible said it consulted with PETA before undertaking the rat studies and used a PETA-approved contract research organization.

The effort seemed to have paid off: The company resubmitted its application and, last month, announced that it had received a “no questions” letter from the agency, essentially saying that its signature ingredient doesn’t raise safety concerns with the regulators.

Impossible Foods saw the deaths of the 188 rats as a trade-off for the greater good. PETA saw it as an unacceptable decision. “It’s impossible for PETA to get behind the Impossible Burger,” the group said in a blog post, which along with a video and social media posts, characterized the product as unhealthy, morally compromised, and inferior to a competing veggie burger.

Impossible Foods went on the defense. It posted its own blog post and a detailed list of what it says are factual errors in PETA’s communications.

And Michael Eisen, a University of California, Berkeley, geneticist and a paid adviser to Impossible Foods, didn’t hold back when it came to arguing with PETA on Twitter.

“They chose to really slime Impossible Foods with all sorts of things that were irrelevant and false to back up their claim that animal testing was a bad thing,” Eisen told STAT. (Kathy Guillermo, a senior vice president at PETA, disputed the notion that the group said anything false.)

One of the major sticking points in the dispute is the question of whether Impossible Foods really needed to do the animal testing. Eisen said the company didn’t have a practical choice if it wanted to achieve its goals. “It was made very clear to us that as we got to larger and larger customers — fast-food chains and institutional clients and ultimately grocery stores — that they would require that we get this [stamp of approval] from the FDA before they would buy our products,” he said.

Eisen said that he sees a certain irony in the fact that PETA “would choose to get all petty” and launch “a broadside against the burger.” If the company succeeds in its mission, “we’re going to accomplish way, way, way more in terms of promoting animal safety than PETA has ever accomplished.”

For PETA’s part, Guillermo called on Impossible Foods to publicly commit to never conducting animal tests in the future. “Helping animals means helping animals. It does not mean helping some and not others. If their goal is to help animals, they need to do just that,” she said.

She added: “If they want food wars, we’re happy to give them food wars.”

This story is adapted from a recent episode of STAT’s biotech podcast, “The Readout LOUD.” Like it? Consider subscribing to hear every episode.