Mustard Oil: For External Use Only?

If you listened to “America’s Test Kitchen” tonight, you heard Chris Kimball and Bridget Lancaster struggle with a listener’s question about mustard oil: Why is it labeled “for external use only,” and is the stuff safe to cook with? Bridget figured, rightly, that the oil was labeled that way to get around “some government regulation,” and that it was probably safe to use in small amounts. At this point I imagined readers of The Joy of Pickling waving their arms and shouting at their radios in their eagerness to supply a fuller answer.

For those of you who haven’t read The Joy of Picklingor at least not cover to cover, yet—here’s the lowdown on mustard oil: In 1989 the U.S. Food and Drug Administration banned its sale for culinary use because some laboratory studies performed in the 1950s associated the oil with nutritional deficiencies and cardiac lesions in rats. Subsequent studies have shown that the results for rats don’t apply to people, and that mustard oil in human diets is in fact associated with a lowered risk of heart disease. In addition, a 1999 U.S. Department of Agriculture report says that mustard oil, like horseradish, contains the pungent antimicrobial chemical allyl isothiocyanate, and that for this reason mustard oil and horseradish “pack a punch against Listeria monocytogenes, E. coli, Staphylococcus aureus and other food pathogens you definitely don’t want in your sandwich.”

Throughout much of India, people have for centuries favored mustard oil for frying and for making oil-based pickles. The unrefined oil has a unique, strong flavor. Use something else—such as raw sesame oil—if you don’t like the taste, but don’t avoid mustard oil out of fear that it will hurt you. Remember that the oil is all in mustard seeds and prepared mustard, which you’ve probably been eating all your life.

You can buy mustard oil at any Indian grocery. Today it’s often combined with cheaper refined oil, so look for the pure stuff. If it’s too strong for you, you can cut it with other oil at home.

Because mustard oil is rich in antioxidants, it will keep for months in a tightly closed container at room temperature.

28 thoughts on “Mustard Oil: For External Use Only?”

  1. I know that in the back of my head there is a political story around mustard oil— this is what I came up with on line.
    BTW I am also very interested to learn about Indian pickling (one of my new year’s resolutions) and one thing that is a puzzle is that the spices are often fried at high heat in the oil– is this ok with mustard oil from an antioxidant point of view? In my experiments so far I’ve simply fermented along with spices, whole and ground, and finished the pickles with grapeseed oil, which tasted neutral and nice, but isn’t to be cooked with. Any comments most welcome…. LOVING this blog! Thanks to you Linda.

    1. Annie, thanks for the link. The political story is complicated and ugly, but I like to think that cooks outside India can give traditional Indian farmers a bit of support by buying a bottle of mustard oil now and then.

      Frying spices in mustard oil brings out their flavors, but it also lessens the oil’s antioxidant properties. Some U.S. chefs use the oil only for finishing, so that it’s heated very little or not at all.

      1. Thank you.

        It’s also interesting to read about Canola oil, as another brassica, and make taste/ health/ marketing comparisons. I live in the UK, where there’s a new push towards “sustainable” smaller scale Rapeseed oils, and the ones I’ve tried are so much more acrid than canolas in the US, so maybe closer to Mustard Seed Oil. All Brassicas. Interesting. So am grateful this blog has started me thinking about all this. (And maybe if the smoke point is higher the Rapeseeds here are a better choice for the pickles?) Anyway– Thank you.

        1. Canola oil, so-named because it was developed in Canada, is made from rapeseed bred for a low erucic-acid content. In U.S. supermarkets, canola oil is refined. The refining process destroys the flavor and nutrients in the oil but also gives it a high smoke point, which makes it useful for frying. But not a lot of heat is required to bring out the flavor of seeds when you’re making Indian-style pickles.

          An alternative to heating mustard oil would be to heat the seeds in refined oil, and then add a little cold mustard oil to the pickle for flavor–if you like the flavor, that is. Honestly, “acrid” is a suitable word to describe it. A taste for mustard oil must be acquired, I think.

          I’ve never tasted unrefined canola oil, but I imagine it would taste much like the “sustainable” rapeseed oils in the UK, and not so different from mustard oil.

          One concern about refined canola oil is that today it’s made mostly from rapeseed that’s genetically modified to resist applications of glyphosate (Roundup). This means that farmers can–and do–spray more herbicide without worrying about killing the crop.

  2. G’Day! Linda,
    Cool Post, Me and my boyfriend didn’t realise untill now, that on the Mustard oil bottle it says ‘For external use only’. Now we’re scared!

    We used it to make pancakes with yesterday, I feel fine.. .But should I be worried? Is it edible
    Kindest Regards

    1. The label was probably added for the U.S. market, unless Australia also bans mustard oil for culinary use. I wouldn’t worry, but you might check with the grocer who sold you the oil.

  3. Your blog provides excellent tips especially to those who are new . Your write ups provide brief and accurate information. Mustard oil is used for strengthening gums, preventing hair loss and boosting immune system. Thanks for sharing this one, a must read write-up.

  4. I have been reading many posts in many websites re mustard oil but not one has mentioned how it is used! In India the oil is ‘unrefined’ so that before adding any food to it the oil must first be heated quite highly so that it is ‘burned off’, pungent acrid smoke coming off (mind your eyes and lungs!).and when you see the smoke and dark colour clears in a few seconds then it is ready to use.

    The US and UK oil labeled as ‘pure’ seems to have this preliminary treatment already done.

    1. Otto, I think the word pure, on a bottle of mustard oil, means what it says: The bottle contains only mustard oil; it hasn’t been cut with canola, peanut, or any other oil. Indian cooks heat mustard oil to the smoking point to reduce the oil’s pungency. It’s easier to reduce the pungency by substituting another oil for some of the mustard oil.

      1. Hi the mustard oil , I have got it in the UK, has very strong pungent smell ( dabur / trs) . So I have to boil it and bring it to the smoke hot point.

  5. Mustard oil has been used for years in northern Italy to make the condiment Mostarda. I use it here in the US for the very same reason.
    Thank you for your very explicit and helpful website.

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