What is the toxic substance in mustard oil?

January 3, 2026 •

3 min read

According to the U.S. Food and Drug Administration (FDA), expressed mustard oil is not safe for human consumption due to high levels of erucic acid. This monounsaturated fatty acid is the primary toxic substance in mustard oil that has led to health concerns and regulatory bans in several countries.

Quick Summary

The main toxic substance in mustard oil is erucic acid, a fatty acid linked to cardiac issues in animal studies. Regulations in some countries, like the U.S., ban its sale for cooking, while other regions have set tolerable limits. Contamination with argemone oil is another, more dangerous risk.

Key Points

Erucic Acid is the main concern: Erucic acid is a monounsaturated fatty acid in mustard oil that caused heart lipidosis in some animal studies, leading to consumption restrictions in several countries.
Consumption is banned in the U.S.: The FDA prohibits the sale of expressed mustard oil for use in cooking, mandating an 'external use only' label.
Adulteration with Argemone Oil is a serious risk: Contamination with toxic argemone oil, which can be mixed into mustard oil, causes epidemic dropsy, a dangerous and potentially fatal disease.
Regulations vary internationally: Unlike the U.S., countries in Asia and the EU have different guidelines. India, for example, widely uses mustard oil, while the EU has specific upper limits for erucic acid.
Always buy from trusted, certified sources: To avoid the risk of adulteration, especially with Argemone oil, it is critical to purchase mustard oil from reputable, well-known brands.
Safer alternatives are available: For those concerned about erucic acid, low-erucic acid rapeseed oil (canola) is a common, widely approved edible oil derived from the same plant family.

Erucic Acid: The Primary Concern in Mustard Oil

Erucic acid is a monounsaturated omega-9 fatty acid found in high concentrations in mustard and rapeseed. Traditional mustard oil can contain 30–60% erucic acid. Animal studies from the 1970s linked high erucic acid intake to myocardial lipidosis, the accumulation of lipids in heart muscle, which reduced contractile force. This led to restrictions in many countries. While human studies haven't definitively proven this link in humans, it remains a factor in regulations. Note that animal studies often used very high doses, and human metabolism differs.

The Deadly Threat of Argemone Oil Adulteration

A more severe toxic threat is adulteration with argemone oil from the Argemone mexicana plant, or Mexican Poppy. Its seeds resemble mustard seeds, increasing contamination risk. Consuming contaminated oil causes epidemic dropsy, a serious condition with symptoms like swelling, heart and respiratory problems, glaucoma, and gastrointestinal illness. The toxic alkaloids, like sanguinarine, are potent and have caused fatalities, as seen in a 1998 New Delhi epidemic. Beware of this risk with low-cost, unregulated oils.

International Regulations and Consumer Awareness

Regulations on mustard oil vary globally, creating confusion. Different standards address the risks associated with its components.

Comparison of Mustard Oil Regulations


Aspect	U.S. Food and Drug Administration (FDA)	European Union (EU) / Food Standards Australia New Zealand (FSANZ)	India (Food Safety and Standards Authority of India - FSSAI)
Erucic Acid Limit	Effectively banned for cooking due to high levels in traditional expressed mustard oil.	Have established upper limits for erucic acid in vegetable oils. The EU maximum for consumer vegetable oils is 2%, while for specific oils like mustard oil, it can be higher (5%).	No ban, but regulations exist for quality standards. Widely used and considered a staple cooking oil.
Sale Status	Expressed mustard oil is for external use only and must be labeled as such.	Sale is regulated and permitted, provided erucic acid levels are within defined safe limits.	Considered safe and sold widely, though consumers are advised to purchase from reputable sources to avoid adulteration.
Low-Erucic Alternatives	Canola oil, a low-erucic acid version of rapeseed oil, is approved for consumption.	Low-erucic acid rapeseed oil is common and used for food production.	Low-erucic varieties exist, but traditional, pungent mustard oil remains highly popular.

The Importance of Quality and Purity

Vigilance is crucial for consumers where mustard oil is a staple. To ensure safety and avoid high erucic acid and adulterants:

Buy from reputable brands: Choose trusted companies with strict quality control.
Look for certifications: In countries like India, look for marks like AGMARK indicating purity.
Choose cold-pressed options: Often considered higher quality, some brands emphasize purity.
Be cautious of unbranded or cheap oils: These are more likely to be contaminated.
Check for safety labels: In countries with bans, ensure the label states 'external use only'.

The Final Word

Mustard oil presents two main concerns: the debated health risks of erucic acid from animal studies and the clear danger of argemone oil adulteration. Prioritize safety and quality by understanding regulations and choosing reputable, certified sources to mitigate risks. Consumer education and quality standards are vital for public health.

Note: Research on erucic acid is ongoing. Consult authoritative bodies for the latest health and food safety guidelines.

Conclusion

Erucic acid is the primary substance cited for traditional mustard oil's health concerns, leading to bans in the U.S. based on animal studies showing cardiotoxicity. However, the most critical risk is adulteration with argemone oil, causing epidemic dropsy. Buy from reputable sources and know local regulations to ensure safety, avoiding unbranded or cheap oils. Low-erucic acid options and alternatives are available for those concerned about intake.

Frequently Asked Questions

The controversy surrounding mustard oil stems from concerns over its high erucic acid content, which has been linked to health issues like myocardial lipidosis in animal studies, leading some regulatory bodies like the FDA to ban its use in cooking.

Animal studies have shown that high levels of erucic acid can cause myocardial lipidosis, an accumulation of fat in the heart muscle. The long-term effects on humans are less clear, but the risk has prompted regulatory action in many countries.

The sale of traditional expressed mustard oil for use as a cooking oil is not permitted in the U.S. by the FDA due to high erucic acid content. It is only allowed for sale labeled as 'for external use only'.

Epidemic dropsy is a disease caused by consuming mustard oil that has been accidentally or intentionally contaminated with argemone oil. It is more dangerous than erucic acid and can lead to severe health problems and even death.

Visual inspection is unreliable since argemone seeds look similar to mustard seeds. One method involves using a chemical test, such as adding concentrated nitric acid, which can produce an orange-yellow color if argemone oil is present. However, the most reliable method is purchasing from reputable brands with quality certifications.

Canola oil and mustard oil both come from plants in the Brassicaceae family, but they are not the same. Canola oil is specifically bred to be a low-erucic acid rapeseed oil, making it safe for consumption and distinct from high-erucic acid mustard oil.

Yes, mustard oil is traditionally used for topical applications, such as hair and skin massages. In fact, in the U.S., it is primarily sold for external use. However, some individuals with sensitivities may experience skin irritation.