The Center for Food Safety is challenging the FDA’s approval of a color additive used to make Impossible Foods’ plant-based burger appear to “bleed” like real meat. The advocacy group claims that the FDA’s decision was not based on “convincing evidence” as required by regulation.

In a brief filed Jan. 28 in the Ninth Circuit U.S. Court of Appeals, the center is specifically challenging the Food and Drug Administration’s 2019 approval of soy leghemoglobin.

“FDA approved soy leghemoglobin even though it conducted none of the long-term animal studies that are needed to determine whether or not it harms human health,” said Bill Freese, science policy analyst at the Center for Food Safety (CFS).

“This includes studies for cancer, reproductive impairment and other adverse effects called for by FDA’s Redbook, the Bible of food and color additive testing. We find this to be all the more troubling because a number of potential adverse effects were detected in a short-term rat trial: disruption of reproductive cycles and reduced uterine weights in females and biomarkers of anemia, reduced clotting ability and kidney problems.”

The novel “heme” colorant is produced in genetically engineered (GE) yeast and is modeled on a protein found in the roots of soybeans. The ingredient is also referred to as genetically engineered “heme,” soy leghemoglobin. It is the color additive Impossible Foods uses to make its plant-based burger appear to “bleed” as if it were beef. 

“FDA’s failure to require Impossible Foods to conduct long-term tests called for in the agency’s own authoritative guidelines means it does not have ‘convincing evidence’ that this color additive, consumed by millions, is safe,” said Ryan Talbott, staff attorney at CFS.

“The approval of soy leghemoglobin must be revoked, unless and until truly convincing evidence proves it to be safe.”

The GE heme is a color additive preparation that also contains more than a dozen yeast proteins.

 In order to make this GMO heme, Impossible Foods uses the process of synthetic biology to extract DNA from the roots of soy plants — wher a small amount of heme is produced — and then inserts the DNA into genetically engineered yeast wher it is fermented to mass-produce the genetically engineered heme.

Because GE heme is new to the human diet, and substantial quantities are added to the Impossible Burger, CFS contends that the FDA should have required extensive safety testing before approving its use as a color additive, as required by law.

The FDA is supposed to have an extremely high bar for approval for color additives in food. The agency’s “convincing evidence” standard means that a color additive cannot be approved without the strongest possible evidence of safety, a higher bar than for other food additives. However, Impossible Foods’ products containing GE heme are now widely available in supermarkets across the country because of what CPS believes was the FDA’s unlawful approval of GE heme as a color additive. according to the center officials.