A handful of recent stories cite potential red flags about the safety of the Impossible Burger, a vegetarian patty made by Silicon Valley startup Impossible Foods, which has backing from Bill Gates.

At the heart of the issue appears to be the company's use of both genetically modified ingredients and a special nutrient called heme. The US Food and Drug Administration has also flagged the latter ingredient, saying it's too "new" to give it a stamp of approval.



Business Insider dug into the scientific research on the ingredients. Studies suggest there is no cause for concern.





Today's veggie burgers can be described with a handful of delicious-sounding adjectives, but "meaty" isn't one of them.

At least it wasn't — until Silicon Valley startup Impossible Foods began creating a meat-free burger designed to reduce waste that tastes disturbingly close to the real thing. The meat-like flavor can largely be attributed to an ingredient called heme — the magic spark that even allows the Impossible Burger to "bleed" like a real burger does.

But that magic spark may be poised to ignite a fire.

In a handful of articles posted recently in places like Bloomberg, Food and Wine, and Inc., people raised two main concerns over the heme in Impossible Foods' burger: First, it is made using genetic engineering, meaning the burger is technically produced with GMOs. Second, some have stated that there could be a link between heme and cancer.

Business Insider spoke with a variety of scientists who hail from distinct backgrounds and research institutions. They say there's no need for concern with regards to either ingredient, citing evidence like a large 2013 review on GMOs which found the ingredients safe to eat. In addition, they've pointed out that the research currently being used as evidence of the link between heme and cancer actually found a connection between red meat and the disease, not heme alone.

But the US Food and Drug Administration seems to be singing to a different tune. So far, the agency has said the ingredient is too "new" to give it a stamp of approval, a caveat that some suggest could block future innovations in the food tech space.

Here's what you need to know.

Heme, the essential nutrient you've never heard of

The Impossible Burger at Public in New York City. Leanna Garfield/Business Insider Heme is an essential nutrient in many proteins. It's also in just about every living thing on Earth. In our bodies, heme can be found tucked inside of a molecule in our blood called hemoglobin. Heme helps ferry oxygen throughout the body, carries iron, and colors our blood red. For most of us, the majority of the heme we consume comes from animals.

But soy roots also contain heme — and that's where Impossible Foods gets theirs.

Still, soy roots only produce a tiny amount of heme, which initially presented Impossible Foods with a problem: They'd need to harvest roughly an acre's worth of soy plants just to get a kilogram of heme.

Yeast saves the day, but at a cost

Instead of doing that, Impossible Foods founder and CEO Pat Brown figured out the company could trick yeast into making heme for them by tweaking its DNA.

The idea of genetically engineering yeast to make other ingredients is not new or rare. Insulin, the compound that diabetics' life depends on to regulate blood sugar levels, is manufactured using GM yeast.

Impossible Foods' heme. Melia Robinson/Business Insider Drugs, beer, and perfume can all be made using yeast as tiny manufacturing powerhouses.

Because they are made with genetically modified yeast, all of these products are also technically GMOs, which have become increasingly unpopular in recent years despite scientists' repeated assertions that they are safe.

Organizations like the National Academy of Sciences, the American Association for the Advancement of Science, and the European Commission have publicly said genetically modified foods are safe to eat. A large 2013 study on GMOs found no "significant hazards directly connected with the use of genetically engineered crops."

Several experts say the "GMO" label does a disservice to the millions of products — some of them life-saving — made with genetically modified ingredients. The process of genetic modification is a breeding method, much like other recent advances in agriculture.

"What are we labeling here, DNA?" Alison Van Eenennaam, a professor of animal genomics at the University of California at Davis, recently told Business Insider. "There's DNA in everything, so good luck with that."

Heme and the 'C' word

The Impossible Burger isn't suddenly controversial just because of GMOs.

Some journalists have also been discussing a potential link between heme and cancer. According to scientists, however, no such link exists.

In an article published in Food and Wine magazine in March, the author wrote that "excessive" heme consumption had been linked to colon and prostate cancer, citing a 2012 blog post in the New York Times.

That assertion appears to be based on the plethora of studies linking red meat — where most Americans get the majority of the heme they ingest — and colorectal cancer. (According to the American Institute for Cancer Research and the World Health Organization, there is a strong link between red meat, especially processed meat, and cancer. The type of cancer with the strongest link is colorectal cancer, a type of the disease that begins in the colon or rectum.)

But no such link appears to exist for heme alone and cancer — potentially because the amount of heme you'd have to consume to reach "excessive" levels would be prohibitively high.

"Considering how much heme we are eating in red meat, I do not see any health issues arising" from putting it in a vegetarian burger, Nicolai Lehnert, a professor of chemistry and biophysics at the University of Michigan, told Business Insider.

Robert Kranz, a professor of biology at Washington State University in St. Louis who's studied heme extensively, said people should not be worried about consuming heme — regardless of where it comes from — because it is an essential nutrient found in animals, plants, and bacteria.

"Heme has therefore been consumed by humans and other animals for a long time with no issues," Kranz told Business Insider.

Studies that have attempted to isolate heme and study its link to cancer separate from red meat have also come up empty-handed, either finding no link or finding a negative one.

In a 2012 study published in the American Journal of Clinical Nutrition that involved a sample of nearly 90,000 men and women, researchers found no tie between heme iron intake and colorectal cancer.

"Our results ... suggest that zinc and heme iron intakes are not associated with colorectal cancer," the researchers wrote.

Iqbal Hamza, a professor of cell biology and genetics at the University of Maryland who runs a lab dedicated to the study of heme and is working on a heme-based supplement for iron-deficient people in developing countries, similarly concluded that the ingredient was perfectly safe for human consumption.

"I would have no qualms about getting heme from the Impossible Foods burger and I would have no qualms about getting heme from a plant based source," Hamza told Business Insider.

A 2011 study published in the journal Cancer Causes and Control also examined a large group of people in an attempt to suss out links between heme and cancer. They found none. In fact, they found a slightly negative relationship between the two things, meaning that people who consumed more heme were actually less likely to develop cancer.

The team behind Impossible Foods agrees.

"It's not a lack of evidence [linking heme to cancer]. There's evidence. And the evidence is for safety," David Lipman, Impossible Foods chief science officer, told Business Insider.