Mustard oil is pressed from the seeds of the Brassica family of plants, including black, brown, and white mustard varieties. It is a traditional cooking medium in South Asia, known for its pungent aroma and sharp flavor. The oil’s status as a food product is debated, creating a distinction between its widespread culinary use and its restricted status in Western markets. This controversy stems from its unique chemical structure and historical findings that led to regulatory actions.
Composition and Types of Mustard Oil
Mustard oil is chemically complex, and its composition varies depending on the processing method, leading to two distinct types. The fixed or fatty oil, obtained by pressing the seeds, is used for cooking. This fixed oil is characterized by a high proportion of unsaturated fatty acids, including 60% Monounsaturated Fatty Acids (MUFAs) and 21% Polyunsaturated Fatty Acids (PUFAs), with a low saturated fat content of about 12%.
A significant component of the fixed oil is erucic acid, a long-chain fatty acid that can constitute between 20% and 50% of the total fatty acids in traditional varieties. The other type is volatile or essential oil, produced by steam distillation of crushed seeds mixed with water. This process releases allyl isothiocyanate, which is the source of the oil’s characteristic sharp flavor. The essential oil is typically approved for use as a flavoring agent and has a much lower erucic acid content than the fixed oil.
Mechanisms of Health Support
The health benefits of mustard oil are attributed to its favorable fatty acid profile and bioactive compounds. The fixed oil contains Alpha-Linolenic Acid (ALA), a plant-based omega-3 fatty acid, which contributes to anti-inflammatory properties. The combination of MUFAs, like oleic acid, and PUFAs is linked to supporting cardiovascular health by helping to manage cholesterol levels. Specifically, monounsaturated fats are known to help reduce low-density lipoprotein (LDL) or “bad” cholesterol.
The oil’s anti-inflammatory potential is supported by studies showing that omega-3 fatty acids can reduce markers of inflammation in the body. Allyl isothiocyanate found in the oil has been studied for its ability to affect pain receptors and exhibit antimicrobial effects. This compound has shown promise in laboratory settings for inhibiting the growth of certain bacteria, such as Escherichia coli and Staphylococcus aureus.
Regulatory Status and Safety Concerns
The primary reason for regulatory caution regarding mustard oil as an edible product is its high concentration of erucic acid. The US Food and Drug Administration (FDA) classifies traditional mustard oil as an unsafe food additive due to typical erucic acid levels ranging from 20% to 40%. This regulatory stance is rooted in historical animal studies from the 1950s that suggested a link between high erucic acid intake and the development of cardiac lipidosis, a condition involving the accumulation of fatty acids in the heart muscle.
Due to these historical concerns, the FDA mandates that most mustard oil sold in the United States must be clearly labeled “For External Use Only” and is not approved for cooking. In contrast, the European Union and other regulatory bodies have set maximum limits for erucic acid in edible oils, typically at 2% to 5% of the total fatty acids. Some low-erucic acid varieties of mustard oil, bred to meet these lower thresholds, have recently received approval for consumption.
Traditional and Topical Applications
Mustard oil has a long history of use in cooking and traditional medicine. In South Asian cuisine, the oil is often heated to its smoke point before use, a process known as “smoking” that tempers its sharp pungency. This high smoke point makes it suitable for high-temperature cooking methods like deep-frying and sautéing. Its natural antimicrobial properties also make it a traditional preservative, often used in pickling.
In topical applications, the oil is widely used as a massage oil for both adults and infants. Its warming properties are believed to improve circulation and reduce muscle tension, making it a popular remedy for joint pain and stiffness. The oil is also a common component in hair and skin treatments, with its antifungal and antibacterial qualities thought to help combat scalp infections and improve hair growth. External uses allow consumers to benefit from the oil’s unique compounds while bypassing the safety concerns associated with dietary intake of high erucic acid content.