Should mustard-allergic people be wary of canola oil?

It’s hard enough to be allergic to one food, but when cross-reactivity strikes, food-allergic individuals may find themselves unable to eat seemingly unrelated food products.

Take the case of mustard. Of all the spices, mustard tends to provoke the most severe allergic reactions. According to Healthline, mustard allergies are most common in the United Kingdom, Canada and India — regions where it’s common as a food ingredient.

Some health agencies have noted the possibility of cross-reaction between mustard and canola oil allergens, although no cases of this happening have been documented. This is because canola oil is derived from certain cultivars of rapeseed. The allergenic components of mustard are very similar to some components found in rapeseed, but not identical.

Health Canada notes that despite the similar proteins in the products, mustard-allergic people probably aren’t at risk of reaction from foods containing canola oil because the highly refined product usually doesn’t have a significant amount of the potentially allergenic proteins. The agency notes, however, that cold-pressed canola oil is less refined, and should be avoided by mustard-allergic people, just in case. The same is advised about rapeseed oil.

Mustard and rapeseed are both members of the Brassicaceae family. For that reason, in addition to rapeseed/canola, mustard-allergic people are advised to be aware when consuming other foods from the Brassicaceae family, like broccoli, Brussels sprouts, cabbage, cauliflower and turnips. Health Canada suggests mustard-allergic individuals avoid the seeds and sprouted seeds of these other vegetables, as they are more likely to trigger a reaction.

How allergic reactions happen

When a food-allergic person eats their allergen, they have an allergic reaction. This means their immune system mistakes allergen protein for something harmful. In response, the body sends histamine and other chemicals to fight the perceived threat, which leads to symptoms like swelling, hives and rashes. In severe cases, respiratory difficulty is possible. A severe allergic reaction is called anaphylaxis.

Anaphylaxis includes symptoms of an allergic reaction plus a shock reaction — a drop in blood pressure and sometimes cardiac arrhythmia. If not promptly treated, it can be life-threatening.

Food allergies affect millions of people around the world — at least 15 million in the U.S., around four million in Australia, and approximately 17 million Europeans. Research shows that food allergies are increasing in prevalence, with a 50% rise in U.S. children between 1997 and 2011.