Erucic acid is a naturally occurring monounsaturated omega-9 fatty acid that is present in the oils of certain plant seeds. Defined chemically as a very long-chain fatty acid, it has the designation C22:1 because of its 22-carbon structure and single double bond. This compound has been a subject of significant scientific and regulatory discussion over decades, primarily concerning its presence in the human diet. Its history involves a dramatic shift from a common dietary component to a strictly regulated substance, driven by early health concerns and leading to the development of new crop varieties.
The Chemical Structure and Primary Sources
Erucic acid is a very long-chain monounsaturated fatty acid, specifically identified as cis-13-docosenoic acid. Its chemical structure, C₂₂H₄₂O₂, includes 22 carbon atoms with a double bond located at the ninth carbon from the methyl end, classifying it as an omega-9 fatty acid. This long-chain structure influences how the body processes the acid compared to shorter fatty acids. The primary natural sources are the seeds of plants belonging to the Brassicaceae family, which includes mustard and rapeseed. High-erucic acid rapeseed (HEAR) oil can contain a very high concentration of this fatty acid, often ranging from 20% to over 54% of its total fatty acids. For industrial use, these high-erucic acid varieties are still cultivated.
Historical Health Concerns and Early Regulation
The concern regarding erucic acid’s safety arose primarily from animal studies conducted in the 1960s and 1970s involving high consumption levels. These studies, mainly in laboratory rats, demonstrated a link between high-erucic acid diets and a condition known as myocardial lipidosis. Myocardial lipidosis is characterized by the temporary accumulation of fatty deposits within the heart muscle cells.
Researchers suggested that the very long-chain structure of erucic acid may interfere with the mitochondrial beta-oxidation system, which is the mechanism cells use to break down fatty acids for energy. This interference resulted in the accumulation of fat in the heart, reducing the contractile force of the muscle. While the lipidosis was often observed to be reversible, prolonged intake in animal models was also associated with focal myocardial degeneration.
These findings, along with observed changes in the weight of the liver and kidneys in animals, triggered significant regulatory action worldwide. Although the cardiotoxic effects were not confirmed in humans, the animal data provided sufficient evidence for health authorities to act out of caution. Regulatory bodies in North America and Europe introduced limits to restrict the erucic acid content in edible oils, effectively mandating the phase-out of high-erucic acid oils from the commercial food supply.
Erucic Acid in Today’s Food Supply
The response to the historical health concerns was the large-scale development of new plant varieties through selective breeding. Scientists bred rapeseed plants to produce oil with significantly lower erucic acid content. This led to the creation of low-erucic acid rapeseed (LEAR) oil, which is widely marketed today under the trade name Canola oil.
The term “Canola” is often cited as an acronym for “Canadian Oil, Low Acid,” reflecting its origin and primary characteristic. Canola oil is chemically distinct from its high-erucic acid predecessor, with the majority of its fatty acids consisting of oleic acid.
The United States Food and Drug Administration (FDA) regulatory code dictates that edible low-erucic acid rapeseed oil must contain no more than 2% erucic acid as a percentage of the total fatty acids. This strict limit ensures that the levels of erucic acid in the modern food supply are minimal. Current scientific consensus holds that the consumption of these low-erucic acid oils at established regulatory levels does not pose a health risk to the general population.
Industrial and Commercial Applications
Despite its decline in the food industry, erucic acid remains a valuable industrial commodity. High-erucic acid rapeseed varieties are still cultivated specifically to supply the chemical industry. Erucic acid is prized for its unique chemical properties, including its high oxidative stability and low-temperature fluidity.
The acid is a precursor for the production of several specialized chemicals, such as brassylic acid, which is used to make specialty polymers and polyesters. Amides derived from erucic acid are widely used as lubricants and surfactants. Furthermore, its emollient and moisturizing properties lead to its incorporation into personal care products, including cosmetics, creams, and lotions.