Serghei Starus, Alamy You've probably never had real wasabi, no matter how much sushi you've eaten.

The vast majority of wasabi consumed in America is simply a mix of horseradish, hot mustard, and green dye, according to a new video from the American Chemical Society.

In fact, about 99% of all wasabi sold in the US is fake, The Washington Post reports.

Even in Japan where most wasabi is grown, you won't have much better luck. Experts estimate that about 95% of wasabi sold in the country is an imitation.

True wasabi is difficult to grow and extraordinarily expensive, costing $160 a kilogram at wholesale prices.

This is what actual wasabi looks like. Chris 73 / Wikimedia Commons

If you're eating real wasabi, you're consuming the stem of a plant, grated and pulverized into a spicy paste. It reportedly has a more complex taste, but needs to be eaten immediately — within 15 minutes, the freshly grated wasabi begins to lose its signature flavor.

Horseradish has a similar chemical makeup to wasabi, allowing it to mimic its spicy zing. The far-cheaper horseradish-based "wasabi" also has the added bonus of withstanding takeout sushi orders in a way that true, freshly grated wasabi could not.

Food fraud is a $50 billion annual industry. In most cases, food scams aren't dangerous to consumers' health.