Wasabi, also called Japanese horseradish, is a member of the cabbage family. The stem of this plant is used as spice that is of very strong pungency; it has been used in this manner for all of recordable Japanese history. The chemical compound responsible for wasabi’s distinct spice is actually the same as in mustard and horseradish: allyl isothiocyanate. This compound is water soluble compared to hot peppers’ oil soluble compounds, which is why the wasabi spice seems to fade much more quickly than the pepper spice. Since wasabi is only consumed in spice quantities, there is little value in reviewing its nutritional contents.
Wasabi powder is simply dried wasabi stem, but this spice has been notoriously adulterated with other less rare substances, so getting your wasabi powder from a reliable source is very important. I like to get Eden brand wasabi powder from Amazon.