What is wasabi and why does it have such a spicy kick?

Few foods we eat today go back as far as does wasabi. Archeological evidence of its use has been discovered dating back to 14,000 BC, and it was cited in the Honzo Wamyo - Japan's oldest encyclopedia of medicinal plants, per one report. It was used anciently as a preservative, a seasoning, and medicinally for its antibacterial properties.  

Thousands of years later, wasabi is even more relevant, with the global wasabi market reaching nearly $400 million in 2022 and expected to increase to more than $652 million by 2028, according to one market analysis. Despite its impressive growth, the mass-produced version of wasabi that most people consume in the West today isn't the same as its ancient Eastern counterpart.  

What is wasabi? 

Wasabi is a spicy, bright-green condiment paste that is frequently served alongside sushi. Also called Japanese horseradish, it's known for its instant kick and lingering flavor that's similar to hot mustard or horseradish - two other condiments that come from the same cabbage-type Brassicaceae plant family as wasabi. Within this family, wasabi comes from the Wasabi japonica or Eutrema japonicum plant, which is native to Japan, South Korea and parts of Russia. 

Though it's also sold as a powder, "the root of wasabi is the part that is used in culinary applications," explains Leslie Bonci, MPH, RDN, a sports dietitian for the Kansas City Chiefs and founder of Active Eating Advice.

That root is grated and ground into a paste, "which then resembles what most people think of as wasabi," explains Julia Zumpano, a registered dietitian at Cleveland Clinic’s Center for Human Nutrition.

Are there different kinds of wasabi? 

Despite its deliberately similar appearance and taste, many people have only tried the Western version of wasabi and not authentic wasabi. "Real" wasabi, as it's sometimes called, is Japanese wasabi. It's farmed and produced in Eastern countries, but is difficult to grow, "which makes cultivation expensive," says Audra Wilson, MS, bariatric dietitian at Northwestern Medicine Delnor Hospital.

Horseradish, on the other hand, is easier to grow and more readily available, so most of the wasabi people eat today is called Western wasabi - often referred to as "fake" wasabi. "It is estimated that 99% of the wasabi eaten in the United States is 'fake' and is actually a mix of grated horseradish and mustard powder, then colored with green food coloring," explains Wilson. "Though the taste is similar, authentic wasabi is much less sharp and astringent – and much more costly." 

Why is wasabi so spicy?

Less sharp as it may be, both Eastern and Western wasabi are known to have a "strong spicy flavor," says Zumpano. Wasabi gets this kick from an organic chemical compound called allyl isothiocyanate - a compound that's also found in the same plant family that horseradish and hot mustard come from, explaining why all three products have a similar kick. Wasabi also has enzymes known as glucosinolates, which break down and give the condiment an especially pungent taste. 

While its distinctive flavor isn't for everyone, those who can tolerate wasabi - often made more palatable by mixing it with soy sauce - may be avoiding some calories. "Despite it having a strong flavor," says Wilson, "wasabi can be a good alternative to higher-calorie condiments, which can reduce overall calorie intake."

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