What foods contain ergot? A guide to contaminated grains

November 17, 2025 •

4 min read

Ergotism, historically known as St. Anthony's Fire, was responsible for devastating epidemics throughout medieval Europe due to contaminated grains. While outbreaks are extremely rare today, it is still crucial to understand what foods contain ergot and how modern food safety controls minimize the risk of contamination.

Quick Summary

Ergot, a toxic fungus, can contaminate cereal grains like rye, wheat, barley, and millet. It produces toxic alkaloids, posing a food safety risk through the consumption of infected grain products.

Key Points

Cereals are the primary host: Ergot predominantly contaminates cereal grains such as rye, wheat, barley, and oats, as well as various wild grasses.
Rye is most susceptible: Due to its open-pollinating flowers, rye is especially vulnerable to ergot infection by the fungus Claviceps purpurea.
Ergotism is rare but serious: Human poisoning (ergotism) is now uncommon due to modern controls, but symptoms, including convulsions and gangrene, are severe.
Toxins resist heat: The ergot alkaloids are highly stable and are not destroyed by cooking or baking processes.
Detection is difficult for consumers: Ergot alkaloids cannot be identified by sight, smell, or taste in flour, requiring professional analytical methods.
Prevention is key: Modern control relies on good agricultural practices, crop rotation, and sophisticated post-harvest cleaning and sorting techniques.

Understanding Ergot and Contamination

Ergot is the common name for the hard, dark-colored fungal bodies, or sclerotia, produced by species of the genus Claviceps. The most notable species is Claviceps purpurea, which infects the developing grains of cereals and grasses. When fungal spores land on the flower of a susceptible plant, they infect and eventually replace the healthy grain with a toxic, hardened sclerotium. These ergots contain various alkaloids that can cause severe health problems if ingested.

The contamination process is a cycle that starts in the field. Sclerotia overwinter in the soil and, under cool and wet conditions, germinate to release airborne spores that infect flowering plants. This initial infection creates a sticky, spore-filled substance known as 'honeydew', which attracts insects and is spread by rain splash, leading to secondary infections. The sclerotia mature within the plant's seed head and are harvested along with the healthy grain, creating a risk for the food supply. Even if the sclerotia are removed, toxic dust and fragments can remain.

Foods and Grains Most Susceptible to Ergot

Ergot is most commonly associated with rye, but it can infect a wide range of cereals and grasses. The level of risk depends largely on the grain's flowering habits; open-pollinated grains like rye are particularly vulnerable.

Main Susceptible Cereal Grains

Rye: Highly susceptible due to its cross-pollinating nature and open flowers, making it a primary host for Claviceps purpurea. Foods like rye bread and rye flour are at higher risk if processing controls fail.
Wheat: Both common and durum wheat can be affected, though they are less susceptible than rye due to their self-pollinating nature.
Barley: Also vulnerable to ergot infection, with documented cases of contamination affecting both human and animal feed.
Triticale: This hybrid of wheat and rye can also be infected, often showing higher levels of contamination than wheat.
Millet and Sorghum: Certain species of Claviceps infect millet and sorghum, posing a risk in regions where these are staple foods.
Oats and Maize: While less frequently affected, they are not immune to ergot infection.

Products Made from Contaminated Grains

The toxic alkaloids within ergots are stable and resistant to degradation from heat, meaning processing methods like baking do not eliminate them. Therefore, contaminated grain can lead to contaminated end-products. These include:

Flour and flour-based products (breads, pastries)
Pasta and noodles
Breakfast cereals
Beer and other grain-based beverages

Symptoms and Risk of Ergotism

Ergot poisoning, or ergotism, can manifest in two distinct forms, both of which were described in historical accounts of St. Anthony's Fire.

Symptoms of Ergotism

Gangrenous Ergotism: Caused by the vasoconstrictive effects of the alkaloids, leading to restricted blood flow. Symptoms include intense burning pain, swelling, and gangrene of the extremities, which can lead to the loss of limbs.
Convulsive Ergotism: Affects the central nervous system, causing painful spasms, seizures, hallucinations, psychosis, and a crawling sensation on the skin.

While human ergotism is a rarity today thanks to stringent food safety regulations, it still occurs, particularly in regions with less effective controls. Outbreaks also still affect livestock who consume contaminated feed.

Modern Controls and How to Avoid Ergot

Today, several control strategies are used to prevent ergot from entering the food supply, from field management to post-harvest processing.

Prevention Strategies

Good Agricultural Practices (GAP): This includes using clean seed, practicing crop rotation to limit soil inoculum, controlling wild grasses in and around fields, and proper field tillage.
Post-Harvest Cleaning: Modern technology, such as optical color sorters and gravity separators, can effectively remove the dark ergot bodies from harvested grain. However, this process is expensive and may not remove all contamination.
Regular Monitoring: Food safety authorities and producers regularly monitor cereal crops and products to ensure ergot alkaloid levels remain below regulatory limits.
Avoiding Contaminated Food: Consumers should avoid using home-grown grain unless it has been thoroughly inspected. If mold is noticed on any grain-based product, it should be discarded immediately.

Comparative Susceptibility of Cereals to Ergot


Cereal Type	Susceptibility Level	Notes
Rye	High	Most susceptible due to its open flowers and cross-pollination.
Triticale	Medium-High	Hybrid of wheat and rye, showing moderate to high vulnerability.
Wheat	Medium	Less susceptible than rye but still at risk, especially in wet seasons.
Barley	Medium	Can be infected, posing risks to both human and animal feed.
Oats	Low	Seldom affected compared to other cereals, making it a lower-risk option.
Maize & Sorghum	Variable	Vulnerability depends on the specific Claviceps species and regional conditions.

Conclusion

Ergot is a historical and modern concern in food safety, primarily affecting cereal grains such as rye, wheat, and barley. The ingestion of ergot sclerotia, either directly or through contaminated flour and products, can lead to ergotism, a severe illness characterized by convulsive or gangrenous symptoms. While modern agricultural and processing techniques have drastically reduced the risk of widespread epidemics, the potential for low-level contamination remains. Through strict adherence to food safety regulations, effective grain cleaning, and careful monitoring, the threat of ergot in the food supply is successfully managed in many parts of the world. Consumer vigilance, especially regarding small-scale or home-grown grains, is a final key to preventing exposure to this historic toxin. For further information on the pathology and management of ergot, refer to reputable agricultural sources, such as the American Phytopathological Society's resources on ergot of rye.

Frequently Asked Questions

Yes, but the risk is extremely low in developed countries due to effective food safety regulations and advanced grain cleaning technologies. Historically, large-scale outbreaks occurred, but today's systems prevent significant contamination from reaching most human food products.

Rye is the cereal grain most susceptible to ergot contamination. The fungus infects its open, cross-pollinating flowers more easily than other grains like wheat and oats.

Yes, the ergot bodies are hard, dark-colored fungal growths that replace healthy grain kernels. They are often larger than the seed itself and can be clearly visible in uncleaned grain.

No, ergot alkaloids are highly stable and are not significantly degraded by high-heat processes like baking, frying, or cooking. The only way to remove the risk is to prevent the contaminated grain from being processed into food.

Gangrenous ergotism results from severe vasoconstriction caused by the toxins, leading to burning pain and potentially gangrene in the extremities. Convulsive ergotism is characterized by painful spasms, seizures, and psychological effects like hallucinations.

Livestock that consume ergot-contaminated feed can develop ergotism, leading to symptoms like lameness, gangrene of the extremities (ears, tails, feet), reduced milk production, and seizures. Toxic effects can occur even at low concentrations.

Prevention involves agricultural practices like crop rotation and deep plowing to manage inoculum in the soil. Post-harvest, grain is cleaned using equipment like color sorters and gravity separators to physically remove the ergot bodies.