Impossible Burger & Estrogen: The research

Will the estrogen in an Impossible Burger grow man boobs?  The answer will surprise you!  But this whole debate is representative of some serious problems we have with nutrition and health claims.

The internet and social media platforms are absolutely exploding over this debate: Will eating the Impossible Burger (now sold by Burger King) cause men to grow boobs?

The short answer: We actually don’t know if it will or won’t.

The Estrogen Claim

The original claim started surfacing a few weeks ago and was first made by a veterinarian by the name of James Stangle.  He said that four Impossible Burgers a day would be enough estrogen to cause a man to grow breasts [also known as Gynecomastia].  

You can see the original post that was sent to me on the right.  And it has quickly circulated around Facebook, Instagram, and Twitter.  I’m sure you’ve probably seen or heard about it by now.

The graphic compares a beef hamburger’s estrogen level to that of the new Impossible Burger.  And then states that it is so much estrogen that four burgers a day would cause “male breast growth.”  

impossible burger and estrogen

What are Phytoestrogens?

Phytoestrogens are plant compounds that are structurally similar to human estrogen.  They occur at higher rates in legumes and vegetables.  Soy has a high level of isoflavones, one type of phytoestrogen and flax seed are also known to have very high amounts of lignans, which are a different phytoestrogen.  It is a natural compound that occurs in the plant. 

impossible burger estrogen

Meat and animal products on the other hand, have a very small amount of phytoestrogens.  Here on the left you can see a comparison by J. Agric, Food Chem, Vol. 56 No. 21, 2008.  This study addresses the actual phytoestrogen content in all types of meat and animal products.  And includes the content in meat substitutes.

This table to the right shows that there is definitely more phytoestrogen in meat substitutes than in the animal products.  Which makes sense, since the phytoestrogens are specifically a plant compound.  Therefore, they would be more prevalent in a plant substance.

So we can see that the actual base of the argument is factual.  There is quite a bit more estrogen-like compounds in the Impossible Burger than in the beef hamburger.  But now let’s look at the second half of the claim.

Estrogen vs. Phytoestrogen

Ultimately, the claim presumes that phytoestrogen and estrogen behave the same way in and humans and has the same effect.  But this may not actually be the case.  Just because it is similar does not necessarily mean that it would be processed the same and therefore cause gynecomastia.  And surprisingly, the research is actually very unclear on the answer.

There are some studies that have consistently shown the health benefits to phytoestrogen.  They say that it may relieve certain menopausal and premenstrual symptoms, acne, and prevent breast cancer.

You can read about a study indivating these health benefits here.  But the same amount of studies show it acting as an endocrine-disrupter and contributing to the growth of cancer and hormone dysfunction, like this study.  

The most recent research I found reinforces this doubt.  In J. Rietjens, British Journal of Pharmacology, (2017) 174, 1263-1280 conclude, “that a definite conclusion on possible beneficial health effects of phytoestrogens cannot be made.”  They site insufficient support for a “refined quantitative risk-benefit analysis,” that would accurately be able to weight the variables.  

Research on Phytoestrogen & Estrogen

The research itself is hard to compare and understand because there are so many factors and variables at play.  We have to consider whether the study was performed on animals or humans, whether is was 1 or many participants, ethnic group or epigenetic differences, and even hormone-level variations.  It is impossible to be able to control for all of these confounding variables in order to get a clear answer.

impossible burger estrogen

It is even important to consider the type of food that was used in the experiment.  For example, did they use flaxseed or soy, was it whole or processed, fermented or not?  We have no idea what little variable may alter the outcome or change the effect.  

I was able to find one study that found phytoestrogens specifically in cruciferous vegetables could be both a benefit and a hindrance.  

YH. J, Food Chem. 2000 Oct; 48(10): 4628-34 claimed that at low concentrations it acted as a antiestrogen but at high concentrations an estrogen agonist.  Which means at low levels it is not behaving as an estrogen, but it is at high levels.

Impossible Burger Recommendation

So part of the claim is accurate, but we really don’t know if the estrogen in the Impossible Burger will behave the same as human estrogen and cause men to grow boobs.

There are many cultures around the world that consume huge amounts of phytoestrogen containing plants.  Many Asian cultures rely on soy as a staple food, and are considered to be a very health population.  But ultimately, consuming too much of anything, even something good for you, is a bad idea.  

This is still a highly processed hamburger from a fast food place.  I really doubt anyone could or would want to eat four of these every day for any consistent amount of time.  

For now, enjoy it on occasion.  I try to stay up on the latest research and will definitely update this article if I hear any new information or if things change.  But for now, consider who is making the claims and analyze their assumptions.  A lot of times the situation is far more nuanced.  Especially when it comes to health and wellness.