What are the health risks of Quorn?

October 5, 2025 •

4 min read

According to a 2018 analysis by the Center for Science in the Public Interest (CSPI), mycoprotein, the main ingredient in Quorn, has been linked to numerous reports of adverse gastrointestinal and allergic reactions. These findings raise important questions about the potential health risks of Quorn for some consumers, despite its promotion as a healthy meat alternative.

Quick Summary

Reports of adverse reactions to Quorn's fungal protein ingredient, mycoprotein, indicate potential health risks, primarily including gastrointestinal issues and allergic reactions in sensitive individuals.

Key Points

Source of Mycoprotein: Quorn's protein, mycoprotein, is derived from the fermented fungus Fusarium venenatum.
Gastrointestinal Distress: The most common health risks include digestive issues like nausea, vomiting, and diarrhea, possibly caused by mycoprotein's high fiber content.
Allergic Reactions: Quorn can cause allergic reactions, including hives and breathing difficulties, especially in individuals with existing mold allergies.
Anaphylaxis Risk: In rare, severe cases, mycoprotein has been linked to life-threatening anaphylactic shock.
Cross-Reactivity: A risk of cross-reactivity exists for people with mold allergies, who may also react to mycoprotein.
Ingredient Transparency: Recent labeling changes in the US now state that mycoprotein is a mold, following concerns raised by consumer advocacy groups.
Start with Small Portions: Health experts suggest trying a small amount of Quorn to gauge your body's reaction, especially if you have known sensitivities.
Regulatory Debate: Despite FDA's GRAS status, organizations like CSPI continue to raise concerns over the safety and proper labeling of mycoprotein.

What is Quorn and its main ingredient, mycoprotein?

Quorn is a popular brand of meat substitutes widely available in the United States, Europe, and other countries. It is marketed to vegetarians, vegans, and those looking to reduce their meat consumption. The core ingredient in all Quorn products is mycoprotein, a protein derived from a type of fungus (or mold) called Fusarium venenatum through a fermentation process. While Quorn is generally recognized as safe for most people and offers a nutritious source of complete protein and fiber, its fungal origin is the source of potential health concerns for a subset of the population.

The two primary health risks of Quorn

Scientific reports and consumer complaints highlight two main types of adverse reactions associated with consuming Quorn: gastrointestinal issues and allergic reactions. The severity and prevalence of these reactions are points of contention between consumer advocacy groups and the manufacturer, with self-reported data suggesting more frequent incidents than company estimates indicate.

Gastrointestinal side effects

Many consumers report significant digestive upset after eating Quorn products. These symptoms can range from mild discomfort to more severe issues. The high fiber content in mycoprotein is hypothesized to be a contributing factor, as rapid fermentation in the large intestine can lead to gas, bloating, and diarrhea, especially in individuals with existing gut sensitivities or an imbalance in gut bacteria.

Nausea and vomiting: One of the most commonly reported adverse effects, occurring in a significant number of consumers.
Diarrhea and abdominal cramps: Frequent symptoms resulting from the rapid fermentation of mycoprotein's high fiber content.
Abdominal pain: Reported pain in the stomach area often accompanies feelings of nausea and cramps.

Allergic and anaphylactic reactions

For some individuals, Quorn can trigger a true allergic response. This is a potentially more serious risk, especially for those with existing mold allergies. In rare cases, these reactions can be severe and life-threatening. The cross-reactivity between the fungal protein in Quorn and other molds can lead to unexpected reactions.

Hives and swelling: Skin reactions, including urticaria (hives) and angioedema (swelling), can occur.
Respiratory issues: Difficulty breathing, asthma, and swelling of the throat are known allergic responses.
Anaphylaxis: The most severe form of allergic reaction, involving a systemic response that can cause a dangerous drop in blood pressure and unconsciousness.

Comparison of risks: Quorn vs. Common Meat Alternatives

Understanding the relative risks of Quorn compared to other popular meat substitutes can help consumers make informed choices. The following table compares key risk factors.


Feature	Quorn (Mycoprotein)	Soy-Based Products (e.g., Tofu, Tempeh)	Plant-Based Isolates (e.g., Impossible Burger, Beyond Burger)
Primary Ingredient	Fermented fungus (Fusarium venenatum)	Soybean	Protein isolates (pea, soy) and other plant-based components
Allergy Potential	Linked to allergies in individuals sensitive to molds and fungi.	Contains a common allergen (soy), though less frequent than mold allergies.	May contain various allergens depending on formulation (e.g., pea protein).
Digestive Issues	Gastrointestinal upset (vomiting, diarrhea) reported by some due to high fiber and rapid fermentation.	Can cause gas and bloating for some, especially those with soy sensitivities.	Can cause digestive issues depending on protein and fiber content, though often less problematic than mycoprotein.
Processing Level	Processed through fermentation and heating.	Varies from minimally processed (tofu) to highly processed (many imitation meats).	Highly processed, combining various ingredients and additives.
Regulatory Status	Approved as "Generally Recognized as Safe" (GRAS) by the FDA, with labeling changes mandated after lawsuits.	Long-established food source, widely regulated.	Accepted by regulatory bodies, subject to standard food safety regulations.

Steps for managing Quorn-related health risks

For those who have experienced adverse reactions or have concerns, there are steps to consider:

Read ingredient labels carefully: Always check the product label for the presence of "mycoprotein" and other potential allergens, such as egg whites, which are sometimes used in non-vegan Quorn products.
Start with small amounts: When trying Quorn for the first time, begin with a small portion to see how your body reacts before incorporating it regularly into your diet.
Consult a healthcare professional: If you suspect you have an allergy or intolerance to Quorn, or experience severe symptoms, speak with a doctor or allergist for proper diagnosis and guidance.
Consider alternative protein sources: If Quorn proves problematic, a variety of other meat substitutes exist with different protein bases, including soy, pea, and other vegetables.

Conclusion

While Quorn provides a sustainable and nutritionally sound alternative to meat for many, the potential health risks for some individuals, particularly those prone to allergies or digestive sensitivities, cannot be overlooked. The primary ingredient, mycoprotein, a fermented fungal protein, has been linked to cases of gastrointestinal distress and allergic reactions, including potentially fatal anaphylaxis. Given these documented risks, consumer advocacy groups have pushed for more transparent labeling to alert consumers to the fungal origin of mycoprotein. By understanding and recognizing the potential side effects, and consulting with healthcare providers when necessary, consumers can make informed decisions about whether Quorn is the right dietary choice for them. For those with confirmed sensitivities, exploring alternative protein options is a safe and prudent course of action. For further information and research on the potential adverse effects, the Center for Science in the Public Interest (CSPI) provides extensive data and reports on Quorn and mycoprotein at their website.

Frequently Asked Questions

Mycoprotein is a protein-rich ingredient made from a naturally occurring fungus, Fusarium venenatum, that is fermented and processed to create the meat-like texture found in Quorn products.

While the manufacturer suggests that allergic reactions are exceptionally low, consumer advocacy groups like the Center for Science in the Public Interest have collected thousands of self-reports detailing allergic and gastrointestinal issues.

Common gastrointestinal side effects reported after consuming Quorn include nausea, vomiting, abdominal cramps, and diarrhea.

Individuals with existing allergies to molds or fungi are at a higher risk of experiencing a cross-reactive allergic reaction to Quorn. Those with sensitive digestive systems or conditions like IBS may also experience issues.

Given that mycoprotein is a fungal protein, it is not recommended for individuals with mold allergies due to the risk of cross-reactivity and potential allergic reactions.

Symptoms can include digestive upset such as nausea or cramps, or allergic reactions like hives, swelling of the mouth or throat, or difficulty breathing. Seek immediate medical attention if breathing is affected.

Some reports suggest mycoprotein is more likely to cause reactions than some other common food allergens, though this is debated. Alternatives like soy-based products may be better tolerated by some.

Yes, following legal action, Quorn labels in the United States must now state that mycoprotein is a mold and that rare cases of allergic reactions have occurred.