Are Plant-Based Burgers a Healthier Option?

F. Perry Wilson, MD, MSCE


October 23, 2019

Welcome to Impact Factor, your weekly dose of commentary on a new medical study. I'm Dr F. Perry Wilson.

This week, we're taking a break from digesting the latest big clinical trial to take a bite out of a new product that has—overnight, it seems—popped up everywhere: the meatless burger.

But I don't want to focus on the taste or texture or bloody appearance. I'd like to focus on the science and the implications for medicine.

We've had veggie burgers forever, which don't taste like hamburgers. But there is something new under the sun, it seems. We now have the "Impossible Burger" by Impossible Foods.

Image from Impossible Foods

What sets these patties apart from the typical veggie burger fare are two things. First, on a macronutrient level, they are really quite similar to beef patties. Take a look at the breakdown of protein and fats in the Impossible Burger compared with your typical veggie burger and an 85% lean hamburger.


You can see that in terms of protein, fat, and total calories, an Impossible Burger looks a lot like a regular old hamburger.

But the secret sauce in all of this may be this little molecule called leghemoglobin—so called because it is a hemoglobin-like molecule that comes from legumes.


You'll recognize heme, that little iron-binding molecule at the center of hemoglobin and myoglobin. It's what gives meat some of that bloody, iron-y, meaty flavor and appearance. Leghemoglobin was initially derived from soybean roots, where it is used to supply oxygen to those nitrogen-fixing bacteria in the root nodules to do their nitrogen-fixing business. Impossible Foods actually has transgenic yeast producing their leghemoglobin.

In [August] 2019, leghemoglobin was approved as a food color additive by the FDA. It's red, after all, and that opened the Impossible Burger to the mass market, hence the hype.

Is it safe? Probably. A bioinformatic study suggests that leghemoglobin shouldn't be allergenic, and rat-feeding studies didn't show any worrying findings. And, of course, we've been ingesting bits of this stuff whenever we eat legumes. But to be fair, there are no long-term data.

So I'm assuming that they're nontoxic, but most vociferously not assuming that they're healthy. While technically this is a veggie burger, it is not trying to be healthy or low-fat; it's simply trying to be meatless, and that it achieves.

As physicians, then, we should not recommend this to patients over meat for health reasons. There are much healthier plant-based foods to eat. But if a patient wants to limit meat consumption for ethical, environmental, or other reasons, with the power of some biochemistry, the challenge seems not quite so impossible.

F. Perry Wilson, MD, MSCE, is associate professor of medicine and director of Yale's Program of Applied Translational Research. His science communication work can be found in the Huffington Post, on NPR, and here on Medscape. He tweets @methodsmanmd and hosts a repository of his communication work at

Follow Medscape on Facebook, Twitter, Instagram, and YouTube


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as: