Mustard oil (MO) is extracted from mustard plant seeds and is a staple in the culinary traditions of South Asia and parts of Eastern Europe. It has a distinct, pungent flavor and aroma, setting it apart from more neutral cooking oils. For centuries, it has been used both for cooking and in traditional medicine, particularly in Ayurveda. However, its health status is subject to significant debate and regulatory scrutiny in Western nations, primarily due to a specific component in its fatty acid profile.
Sources, Processing, and Nutritional Profile
Mustard oil is derived from the seeds of various mustard plants, such as black, brown, or white mustard. It is typically extracted by crushing the seeds, often using cold-pressing (Kachi Ghani), which retains the oil’s natural compounds and sharp flavor. The characteristic pungency is generated during crushing when the enzyme myrosinase reacts with sinigrin, producing Allyl Isothiocyanate (AITC).
Nutritionally, traditional mustard oil is low in saturated fatty acids (8–12%). Its composition is dominated by monounsaturated fatty acids (MUFAs) at about 60% and polyunsaturated fatty acids (PUFAs) at around 21%. The PUFA content includes 6–10% alpha-linolenic acid (ALA), an omega-3 fatty acid.
The Central Safety Issue Erucic Acid
The primary safety concern regarding mustard oil is its high concentration of Erucic Acid, a long-chain monounsaturated fatty acid. In traditional varieties, Erucic Acid often ranges from 30% to over 60% of the total fatty acids, leading to restrictions in several global markets.
This concern stems from animal research conducted in the 1970s. Studies showed that high dietary intake of Erucic Acid could cause myocardial lipidosis, the accumulation of fatty deposits in the heart muscle. Although this condition often reversed when consumption stopped, the findings prompted regulatory bodies to take a precautionary stance.
The restriction is based on the body’s limited ability to efficiently metabolize this long-chain fatty acid. To address this, selective breeding created low-erucic acid varieties of rapeseed oil, a botanical relative of mustard. This resulted in canola oil, which is legally defined as containing less than 2% Erucic Acid.
Traditional Uses and Documented Health Properties
Despite the regulatory controversy, mustard oil is prized in many cultures for its traditional applications. In Ayurveda, the oil is valued for its warming nature and is a common ingredient in therapeutic massage practices. Topical application is thought to relieve muscle stiffness, improve local blood circulation, and reduce joint pain, particularly for arthritis.
The oil’s fatty acid profile offers several documented benefits. The high concentration of MUFAs, similar to olive oil, supports healthy lipid metabolism. Regular consumption is associated with lowering low-density lipoprotein (LDL) cholesterol while maintaining high-density lipoprotein (HDL) cholesterol levels.
The presence of Allyl Isothiocyanate contributes to the oil’s biological activity, giving it antimicrobial and antifungal properties. Studies show this compound can inhibit the growth of certain bacteria and fungi, supporting its traditional use for minor skin infections. Furthermore, the oil contains alpha-linolenic acid, an omega-3 fatty acid that contributes to a reduction in systemic inflammation.
Global Regulatory Status and Consumer Guidance
The regulatory status of mustard oil varies significantly across the globe, reflecting the concern over Erucic Acid content. In the United States and the European Union, standard mustard oil with high Erucic Acid is generally not permitted for use as a cooking oil. The FDA requires imported high-erucic acid oil to be labeled “For External Use Only” or “For Massage Purposes.”
Conversely, in countries like India, Bangladesh, and Nepal, mustard oil is an integral part of the regional cuisine and is widely consumed without such restrictions. This highlights the gap between regulatory caution and long-standing human dietary practice. Consumers interested in culinary use should seek out low-erucic acid varieties that meet the legal threshold of less than 2% Erucic Acid.