Mustard oil is a pungent, golden-yellow oil extracted from the seeds of the mustard plant. It has been a cooking staple across South Asia, particularly in India and Bangladesh, for centuries, and it doubles as a massage and hair oil in traditional practice. In the West, its status is more complicated: the U.S. FDA does not permit its sale as a cooking oil due to concerns about one of its key fatty acids, though it remains widely available labeled “for external use only.”
Two Types of Mustard Oil
The term “mustard oil” actually refers to two distinct products, and the difference matters. Pressed (or expressed) mustard oil is made by crushing mustard seeds to extract their fat, much like olive oil or sesame oil. It’s viscous, sold in bottles similar to other cooking oils, and contains the full fatty acid profile of the seed. This is the version used for frying, sautéing, and pickling across South Asian kitchens.
Essential oil of mustard is a completely different product. It’s made by steam distillation and is dominated by a volatile compound called allyl isothiocyanate, the same molecule responsible for the sharp bite of horseradish and wasabi. Essential mustard oil is sold in small bottles at a higher price point, similar to vanilla extract or other flavorings, and is used in tiny amounts. When people search for “mustard oil,” they almost always mean the pressed cooking oil.
What’s in Pressed Mustard Oil
Mustard oil’s fatty acid profile sets it apart from most cooking oils. Its signature component is erucic acid, a long-chain fatty acid that typically makes up 20 to 40% of the oil, though newer low-erucic cultivars can contain as little as 4%. The oil also contains meaningful amounts of oleic acid (the same monounsaturated fat found in olive oil), along with omega-6 (linoleic acid, roughly 9 to 13%) and omega-3 (alpha-linolenic acid, roughly 8 to 11%). That omega-3 content is notably higher than most common cooking oils.
Beyond the fats, mustard oil contains compounds called glucosinolates. When the seeds are crushed, an enzyme breaks these down into isothiocyanates, which are the source of the oil’s characteristic heat and sharp aroma. These same compounds show antimicrobial and anti-inflammatory activity in lab studies, though how much of that translates to real-world health benefits from cooking with the oil remains unclear.
Cooking With Mustard Oil
In regions where it’s a kitchen staple, mustard oil is prized for its high smoke point of approximately 250°C (482°F). That’s well above olive oil (190 to 220°C), canola oil (204°C), and sunflower oil (225°C), making it especially well suited for deep frying and high-heat stir-frying. Bengali and North Indian cuisines rely on it for fish curries, pickles (achaar), and vegetable dishes where its sharp, almost wasabi-like flavor is considered essential.
A common technique is to heat the oil until it just begins to smoke, then let it cool slightly before adding spices. This process is called “tempering” and mellows the raw pungency while preserving the distinctive nutty, slightly bitter flavor. The oil’s intensity means a little goes a long way, and people who grow up with it often describe it as irreplaceable in certain dishes.
The Erucic Acid Concern
The reason mustard oil faces restrictions in some countries comes down to erucic acid. Animal studies have consistently shown that high, prolonged intake of erucic acid causes fat to accumulate in heart muscle, a condition called myocardial lipidosis. In rats fed diets containing around 22% erucic acid from rapeseed oil, researchers observed significantly more cardiac lesions compared to control groups. The underlying mechanism appears to involve erucic acid slowing the heart’s ability to burn fatty acids for energy, leading to a buildup of fat within heart cells.
Human evidence is more limited but still concerning. A large prospective study tracking over 7,000 participants across two U.S. cohorts found that higher blood levels of erucic acid correlated with increased risk of heart failure, with hazard ratios ranging from 1.34 to 1.92. The European Food Safety Authority set a tolerable daily intake of 7 milligrams per kilogram of body weight per day, noting that young children who consume foods high in erucic acid may exceed this threshold.
The U.S. FDA classifies mustard oil containing unsafe levels of erucic acid as an unsafe food additive and has an active import alert allowing detention of shipments at the border. To get a shipment released, importers must provide lab analysis showing the oil does not contain problematic erucic acid levels. This is why bottles sold in American grocery stores carry the “for external use only” label, even though many consumers buy them specifically for cooking.
Cold-Pressed vs. Heat-Extracted
Within the pressed oil category, cold-pressed mustard oil is extracted by grinding seeds slowly at low temperatures. This preserves more of the oil’s omega-3 fatty acids, antioxidants, and volatile flavor compounds. Heat-extracted mustard oil, produced using higher temperatures to increase yield, loses some of these beneficial components during processing. Both versions contain erucic acid, though cold-pressed oils may retain slightly higher levels since heat can break down some erucic acid during extraction.
Cold-pressed versions tend to have a more vibrant color and a sharper, more pungent flavor. They’re generally considered the higher-quality product and are more expensive. If you’re buying mustard oil for topical use or cooking (in countries where that’s permitted), cold-pressed is the better choice for both flavor and nutrient retention.
Traditional Topical Uses
Outside the kitchen, mustard oil has a long history as a massage oil, hair treatment, and skin conditioner in South Asian households. Parents commonly massage infants with warm mustard oil, and it’s a standard winter skincare remedy in colder regions of India and Pakistan. The oil’s warming sensation on skin comes from the same isothiocyanate compounds that give it its culinary bite. Lab studies show these compounds have antimicrobial properties, which may partially explain the oil’s traditional use on minor skin irritations.
For hair, mustard oil is applied to the scalp and left on for 30 minutes to several hours before washing. Users report that it improves shine and reduces dryness, likely due to its high fat content helping to coat and condition hair strands. However, some people find the oil irritating to skin, particularly those with sensitive skin or eczema, so testing a small area first is a reasonable precaution.
How It Compares to Other Cooking Oils
Mustard oil occupies an unusual niche. Its omega-3 content is higher than most seed oils, its smoke point rivals or exceeds peanut and avocado oil, and its flavor is far more assertive than any neutral oil. The trade-off is the erucic acid question, which no other mainstream cooking oil presents. Canola oil is actually a descendant of rapeseed (the same plant family as mustard) that was specifically bred to contain less than 2% erucic acid, essentially solving the safety concern by changing the plant itself.
For people in South Asia who have cooked with mustard oil for generations, the erucic acid issue is a source of ongoing debate. Population-level heart disease data from mustard oil-consuming regions hasn’t shown the dramatic effects seen in animal studies, though controlled human trials are lacking. Some researchers point out that traditional use involves moderate quantities alongside diverse diets, which is very different from the high-dose animal experiments that raised the initial alarm.