The chic, plant-based Impossible Burger that browns and “bleeds” like the real thing just got a little more possible.

On Monday July 23, the company behind the meatless meat, Impossible Foods, announced that the Food and Drug Administration had finally accepted its latest application to consider the burger’s key ingredient safe to eat. The final nod puts that ingredient—dubbed soy leghemoglobin—firmly in the regulatory category of “generally recognized as safe,” or GRAS.

That’s comforting news for those of us already chowing down on the faux patties, which are currently being fried up in nearly 3,000 restaurants in the US and Hong Kong. Until now, the burgers had flipped into a regulatory gray zone.

Last August, documents obtained through a Freedom of Information Act request revealed that the FDA hadn’t stomached the company’s previous GRAS application . The agency concluded that soy leghemoglobin—a protein found in the roots of soybean plants that Impossible Foods harvests from genetically engineered yeast and uses to simulate the taste and bloodiness of meat—had not been adequately tested for safety.

In the application, Impossible Foods argued that the iron-containing protein is equivalent to hemoglobin, an oxygen-carrying protein in red blood cells and commonly consumed in meat. Thus, the protein was safe, the company concluded. It went as far as conducting studies in rats to back up the claim. But the FDA noted that soy leghemoglobin had never been used as an additive before, and the organization wanted data showing that the protein was safe and not an allergen specifically for humans.

“FDA 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,” FDA officials wrote in a 2015 memo.

Bad aftertaste

At the time, the decision was a searing blow to Impossible Foods, which up until then had fired up the appetites of investors and top chefs alike and savored glowing publicity. Since the company’s founding in 2011, big names such as Bill Gates and Google Ventures served up more than $250 million in startup funds, and the impossible patty sizzled on the menus of such high-end restaurants as Momofuku Nishi in New York and Jardinière in San Francisco. The soy leghemoglobin was a big part of that hype, with the company touting it as its “secret sauce.”

But the FDA’s gut check didn’t knock Impossible Foods off the market; it just left a bad taste. In fact, the company wasn’t even required to submit its GRAS application to begin with due to the controversial way in which the FDA oversees food additives and GRAS designations.

Under the 1938 Food, Drug and Cosmetic Act and the 1958 Food Additives Amendment, the FDA allows food companies and their hired consultants to internally test and determine a GRAS designation of a potential new additive all on their own. They can start using it without getting approval from the FDA or even notifying the agency. The FDA only steps in after the fact if problems arise.

Consumer and health advocates have long railed against this system. There are more than 10,000 chemicals added directly or indirectly to foods in the US and food makers use an estimated 1,000 without notifying the FDA. In a policy statement as recent as Monday, July 23, the American Academy of Pediatrics noted that of the nearly 4,000 additives inventoried by the FDA, only about 263 had reproductive toxicology data, and developmental toxicology data was only available for two of the additives. There are “critical weaknesses in the current regulatory system for food additives,” the academy concluded. It went on:

Data about health effects of food additives on infants and children are limited or missing; however, in general, infants and children are more vulnerable to chemical exposures. Substantial improvements to the food additives regulatory system are urgently needed, including greatly strengthening or replacing the “generally recognized as safe” (GRAS) determination process, updating the scientific foundation of the FDA’s safety assessment program, retesting all previously approved chemicals, and labeling direct additives with limited or no toxicity data.

Safety Slider

Of course, Impossible Foods had only filed its original GRAS application to get an extra dash of awesome sauce for its hit patties—which obviously backfired. By October of 2017, the company had assembled a new, 1,063-page application, which you can read here as a PDF . But the company side-stepped doing additional studies indicating safety in humans specifically. Instead, it relied on additional opinions from consultants, who relied on literature reviews of allergen data, molecular comparisons of similar proteins, and an assay in which the company digested its additive in the presence of simulated gastric fluids. The company's panel of experts argued that Impossible Foods did not need to do additional allergen testing on soy leghemoglobin but that it would nevertheless label its burgers with “Contains Soy” as a precaution.

On Monday, the company announced that the FDA responded with a letter saying:

We have no questions at this time regarding Impossible Foods’ conclusion that soy leghemoglobin preparation is GRAS under its intended conditions of use to optimize flavor in ground beef analogue products intended to be cooked.

In other words, Impossible Foods was free to keep slinging its burgers and to consider soy leghemoglobin safe.

“Getting a no-questions letter goes above and beyond our strict compliance to all federal food-safety regulations,” Impossible Foods CEO and founder Dr. Patrick Brown said in a statement. “We have prioritized safety and transparency from day one, and they will always be core elements of our company culture.”