Portobello Mushrooms: Positive and Negative Effects

In 2017, the mycologist Paul Stamets was featured on Joe Rogan’s podcast to discuss the medical potential of various fungi. At one point, the conversation turned to portobello mushrooms and Stamets said cryptically, “portobellos have a problem.” When asked specifically about the negative effects of portobello mushrooms, Stamets replied “this is an explosive area of conversation, and it puts my life in danger. So, I reserve the right not to answer your question”. Rogan declined to ask Stamets further questions, but notably told his audience “anybody who’s interested, just, Google that and get back to me”. This led to widespread speculation and internet controversy over the potential harms of portobello mushrooms for human health. In this article, we examine the basis of these claims and critically assess their merit in light of current evidence.

Author - Faith Wershba

Postgraduate researcher at the University of Cambridge.

Faith used MediSearch to find sources for this blog.

MediSearch gives instant answers to medical questions based on 30 million scientific articles.

Main takeaway: portobello mushrooms are safe to eat

There is extremely limited evidence demonstrating any adverse effects of consuming portobello mushrooms. While uncooked portobello mushrooms may contain a mycotoxin called agaritine, the quantity of this compound in a typical serving of mushrooms is relatively low and the molecule breaks down readily when mushrooms are cooked. Furthermore, human toxicological studies on the effects of agaritine have not been conducted, which limits the generalizability of scientific claims. To date, studies claiming that agaritine may be carcinogenic have been conducted in animal models using pure agaritine extract at extremely high concentrations. All this being said, eating portobello mushrooms does not have zero risk: for example, individuals with fungal allergies or high uric acid levels may want to be mindful of their portobello consumption.

Portobello mushrooms

What are the health benefits of portobello mushrooms?

Portobello mushrooms have a fairly favorable nutritional profile. They are high in dietary fiber and contain essential vitamins, minerals, amino acids, and antioxidants [2].

Specifically, portobello mushrooms are high in selenium, which has been linked to improved immune function and protection against oxidative stress [3]. For vegetarians and vegans, portobello mushrooms are also a valuable source of plant-based protein, B vitamins, and vitamin D [2].

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