Origins and Primary Sources of Erucic Acid
Erucic acid ($CH_3(CH_2)_7CH=CH(CH2){11}CO_2H$) is an omega-9 fatty acid that is naturally present in the seeds of many plants belonging to the Brassicaceae family, formerly known as the Cruciferae family. Historically, this family included many plants with high levels of erucic acid, but selective breeding has dramatically altered the fatty acid profiles of modern food crops.
The Brassica Family
- Rapeseed Oil: Unmodified, traditional varieties of rapeseed (Brassica napus) contain very high concentrations of erucic acid, sometimes exceeding 40% of the total fatty acids. For this reason, it was originally used primarily for industrial purposes, like lubrication. The development of low-erucic acid varieties in the 1970s led to the creation of canola oil, which is defined as containing less than 2% erucic acid. The term canola is often used interchangeably with low-erucic acid rapeseed (LEAR) oil.
- Mustard Oil: Expressed oil from mustard seeds can contain high levels of erucic acid, with some varieties reporting up to 50%. This has led to regulatory advisories in some countries; for example, the U.S. Food and Drug Administration (FDA) requires that pure mustard oil be labeled for external use only. However, mustard seed oil remains a popular cooking oil in some regions, particularly in Asia.
- Crambe Oil: This is an oil-seed crop (Crambe abyssinica) known for having one of the highest erucic acid contents, often over 60%. Crambe oil is not typically used for human consumption and is reserved almost exclusively for industrial applications.
Less Common and Animal-Derived Sources
Beyond the well-known Brassicaceae oils, other, less common plant seeds and animal products can also contain erucic acid. The levels in these sources are typically lower but are still relevant to overall dietary intake.
- Camelina Oil: Also known as false flax, this oil has a relatively low erucic acid content, usually ranging from 1% to 4%.
- Meadowfoam Oil: Derived from a North American plant, this oil can naturally contain 8% to 24% erucic acid, though cultivated varieties have lower levels. It is primarily used in the cosmetic industry.
- Borage Oil: Marketed as a dietary supplement for its gamma-linolenic acid content, borage oil typically contains 1% to 3% erucic acid.
- Fish and Seafood: Erucic acid can be found in some marine animals. A 2020 study on salmon fillets found erucic acid, along with its isomer cetoleic acid, indicating that fish can be a dietary source. The concentration can vary depending on whether the fish is wild-caught or farmed and what kind of feed is used.
Erucic Acid Levels in High vs. Low Erucic Oilseeds
The difference between older and modern oilseed varieties is critical for understanding dietary erucic acid exposure. Most consumers are now largely protected from high levels due to breeding practices.
| Feature | High Erucic Acid Rapeseed (HEAR) | Low Erucic Acid Rapeseed (LEAR or Canola) |
|---|---|---|
| Primary Use | Industrial applications, such as lubricants and plastics. | Edible oil for human consumption. |
| Erucic Acid Content | Very high, typically over 40-50% of the fatty acid profile. | Legally defined as having less than 2% erucic acid. Most commercially sold oils are much lower, often below 0.5%. |
| Breeding History | The original plant varieties that were widely grown before the 1970s. | Selectively bred in Canada in the 1970s to reduce erucic acid and glucosinolates. |
| Health Implications | High consumption in animal studies linked to myocardial lipidosis. | Considered safe for human consumption; heart-healthy due to high monounsaturated fat content. |
| Regulation | Not intended for food use due to health risks associated with high levels. | Highly regulated in most countries to ensure low erucic acid levels in food-grade oil. |
How Canola Oil Changed the Industry
In the 1970s, Canadian researchers developed a low-erucic acid and low-glucosinolate variety of rapeseed. This breakthrough led to the creation of the term "canola" (from Canadian oil, low acid), effectively transforming a crop that was predominantly used for industrial purposes into a major edible oil crop. The success of canola oil demonstrated that selective breeding could be used to remove potentially harmful compounds from food sources, greatly increasing food safety.
Today, food-grade rapeseed oil (canola) and other widely consumed vegetable oils are strictly regulated to ensure their erucic acid content remains at safe, minimal levels. This provides assurance to consumers that the refined vegetable oils on supermarket shelves do not pose the health risks associated with older, high-erucic varieties.
Conclusion
Erucic acid is naturally present in the seeds of certain plants, with high concentrations historically found in traditional rapeseed and mustard varieties. However, modern agricultural innovation, particularly the development of canola (low-erucic acid rapeseed), has significantly minimized dietary exposure to this fatty acid for the average consumer. High erucic acid rapeseed oil (HEAR) is now primarily used for industrial applications, and food safety regulations strictly limit the erucic acid content in edible oils. While less common sources like certain fish and dietary supplements may contain some erucic acid, they typically do not represent a significant risk under normal consumption patterns, especially in comparison to older, high-erucic oil sources. Awareness of these sources is important for individuals monitoring their diet, but the modern food supply is designed to mitigate the risks associated with this fatty acid.
