If a label simply says 'wasabi paste' without specifying *Wasabia japonica*, what assumption should a consumer make regarding its composition based on cost and availability?

It relies on substitutes like horseradish and mustard due to the high price and difficulty sourcing the genuine rhizome.

Authentic *Wasabia japonica* rhizomes are extremely expensive, sometimes costing hundreds of dollars per pound, and are notoriously difficult to cultivate successfully. Because of these prohibitive factors, the common bright green paste served commercially almost always relies on substitutes, typically horseradish mixed with mustard and green food coloring. If a product does not explicitly state it is made from the genuine rhizome, consumers should assume it contains the less expensive, readily available horseradish base, which alters both the flavor profile and the chemical benefit spectrum.