REDWOOD CITY, CALIF. — Impossible Foods has received a no-questions letter from the U.S. Food and Drug Administration in which the agency accepts the unanimous conclusion of a third-party panel of experts that a key ingredient in the Impossible Burger is safe to eat.

Organizations such as the ETC Group and Friends of the Earth last year argued that Impossible Foods should pull its burger off the market until the F.D.A. agreed all its ingredients were safe. The F.D.A. in the no-questions letter said it had no questions about the Generally Recognized As Safe (GRAS) status of soy leghemoglobin/heme.

“Getting a no-questions letter goes above and beyond our strict compliance to all federal food safety regulations,” said Patrick O. Brown, M.D., Ph.D., chief executive officer and founder of Impossible Foods. “We have prioritized safety and transparency from day one, and they will always be core elements of our company’s culture.”

Redwood City-based Impossible Foods makes meat directly from plants. The plant-based meat contains soy leghemoglobin, a protein that carries heme, which is an iron-containing molecule that occurs naturally in every animal and plant. Heme enables the Impossible Burger to satisfy meat lovers’ cravings, according to Impossible Foods.

The Impossible Burger is found in nearly 3,000 locations in the United States and Hong Kong. Impossible Foods genetically engineers and ferments yeast to produce the heme protein called soy leghemoglobin. The heme in the Impossible Burger is identical to the essential heme that humans have consumed for hundreds of thousands of years, but producing the Impossible Burger uses about 75% less water, generates about 87% less greenhouse gasses and requires about 95% less land than conventional ground beef from cows, according to Impossible Foods.

Impossible Foods hemeThe company began to seek validation for the safety of soy leghemoglobin in 2014, or before it began selling its plant-based burgers to restaurants. A panel of food safety experts gave the opinion that the soy leghemoglobin in the Impossible Burger was GRAS. A 2016 study examined whether consuming soy leghemoglobin in amounts above normal dietary exposure would produce any adverse effects. None were found. A search of allergen databases found soy leghemoglobin had a “very low risk” of allergenicity.

Impossible Foods filed its GRAS findings with the F.D.A. in August 2017. The F.D.A. posted the 1,066-page document from Impossible Foods for public review on its web site. The document may be found here.

The F.D.A. in the no-questions letter also noted soy leghemoglobin could be considered a color additive in some potential future applications. The F.D.A. approves the use of food additives specifically for color through a separate regulatory process. Impossible Foods plans to engage in the process.