Wasabi is an essential side dish for sushi. It should be gluten-free, but at some restaurants, it is reported to have gluten in it.
There are actually two main types of wasabi: real wasabi (which is very rare, especially outside of Japan), and fake wasabi, which is what most people come across, most of the time.
This has important implications for allergies in general, and gluten allergy or celiac disease in particular.
Real Wasabi
Genuine wasabi is made from the root of a “Japanese horseradish”. It’s natural habitat is along mountain streams. It is difficult to cultivate, which is why it is in short supply.
Wasabi is prepared by grating the root. It looses flavor after about 15 minutes.
Wasabi is in the Brassicaceae family of plants, which includes cabbage, broccoli, cauliflower, turnip, rapeseed, mustard, radish, horseradish, cress, and watercress. If you are allergic to most of these plants, you may be allergic to wasabi.
As it is just a grated root, real wasabi is gluten free.
Fake Wasabi
Most people outside of Japan experience an artificial version of wasabi, made from horseradish, mustard, starch and green food coloring.
Like real wasabi, this version contains ingredients from the Brassicaceae family of plants. If you have allergies to these ingredients, you are more likely to have direct experience with the ingredients than with true wasabi.
There is a chance that fake wasabi can contain gluten. I have two brands of wasabi sitting on my desk. One is made from horseradish, mustard and wasabi. It is basically dried real wasabi, cut (or boosted?) with other ingredients. The other is made from horseradish, mustard flour (ground mustard), cor flour, corn starch and food color. It should be gluten-free (unless the mustard is cut with wheat).
Some restaurants tell me their wasabi contains gluten, so you should always ask.
Do you have further information or insight into wasabi? Please leave a comment.