What is Wasabi and what is: Real Wasabi vs. Fake Wasabi

Have you ever wondered what wasabi really is? If you are a fan of Japanese food, chances are you’ve seen it as a pale green paste paired with pieces of sushi or slices of sashimi.

It’s distinctly green, zesty, and divisive … but seriously, what is wasabi, and how is it made? Here’s everything you need to know about Japanese wasabi, including the difference between real and fake wasabi.

If you're interested in seeing firsthand how this rare plant is grown, join a wasabi farm tour in Tokyo!

So, let’s get into it. With the scientific names of Wasabia japonica and Eutrema japonicum, wasabi is a spicy horseradish condiment from Japan best known as an accompaniment for sushi, sashimi, Japanese noodles (like udon), and more.

Also known as Japanese horseradish, real wasabi comes from a plant that belongs to the Brassicaceae family, which typically encompasses other types of radishes, horseradishes, and mustard plants. More root vegetable than spice, real wasabi is made from the rhizome of a wasabi plant, which is its underground stem part. This underground stem is grated finely to create wasabi paste. This is kind of like how ginger is grated, although wasabi is a bit less fibrous. 

So if you were wondering — Was it wasabi horseradish? — The answer would depend on what kind of horseradish you had in mind. Japanese horseradish is not the same as European horseradish, though both plants are in the same family.

See also: 11 spicy Japanese foods to try for a hit of heat.

Over 1,000 years ago, wasabi was not only used to add flavor, but to keep food from spoiling and causing digestive problems. Historical documents from 7th-century Nara show how wasabi was used to help people breathe, as well as extend the use of topical medicines. 

“Wasabi” is almost always available in a Japanese restaurant. But even if you think you’ve tried wasabi before, chances are that you in fact haven’t! Many people who have only eaten wasabi outside of Japan have likely only had an imitation of it.

In Japanese, hon-wasabi (pictured above) refers to the wasabi plant that is native to Japan, while seiyo-wasabi (pictured below) is the word for horseradish that is from Europe (sometimes also called wasabi-daikon). 

Japanese native wasabi is the real deal, but because European horseradish is cheaper, it’s often used to create powdered wasabi and other fake wasabi products. Using a low percentage of real wasabi, seiyo-wasabi is dyed green to make fake wasabi as a cheaper alternative.

Apart from the powdered form used to make paste, wasabi has evolved into a wide range of products. While some of these products are said to contain real wasabi, all are mixed with other ingredients to become more versatile, if not exactly “pure.” Wasabi oil, for instance, mixes wasabi with rapeseed oil. Other forms include wasabi mustard, wasabi mayonnaise, wasabi sauce, and wasabi vodka. 

As the plant can only be grown in very specific environments, wasabi is one of the most expensive crops in the world. This is why a lot of people outside of Japan may have never actually tasted real wasabi before.

The price tag of real wasabi tends to be incredibly high because wasabi plants are notoriously difficult to grow and require very specific conditions. In Japan, the wasabi plant grows naturally in areas that have mountain valleys, where it can grow along the river streambeds.

The ideal growing environment is incredibly rare, and wasabi plants need their stems to be partially submerged in clear running water, adding another level of difficulty to the process. Without running streambeds in Japan’s mountain valleys, cultivating wasabi plants on a commercial level is very challenging, thus making it a pricey plant to grow.

Nagano, Iwate, and Shimane are known for their local production of wasabi. However, the Izu region in Shizuoka Prefecture is the capital of wasabi, producing around 70% of Japan’s wasabi.

If you’re wondering what fake wasabi is, it’s usually regular seiyo-wasabi (horseradish) in disguise. To make this condiment cheaper and more accessible, many fake wasabi products are made from European horseradish and are widely available in supermarkets or at your local Japanese restaurant.

Imitation wasabi can be found in a paste form (often in a squeezable tube or small packet) or powder form (that needs to be mixed with water). Generally speaking, fake wasabi products will only have a tiny amount of real wasabi in them, around just 1 to 3 percent. This small amo

Real wasabi is traditionally made by harvesting the wasabi plant by hand, then using sharkskin to sand the rhizome right before it’s meant to be eaten. Instead of rubbing the sharkskin on the rhizome the way sandpaper is typically used, the rhizome is rubbed over the sharkskin in a circular motion. An oroshigane or grating tool can also be used.

Simply put, the answers to the above are “spicy” and “no.” Distinctly pungent in flavor, wasabi has a similar taste to hot mustard, in how its spiciness hits the nose rather than the tongue like a chili pepper does. True, freshly-grated wasabi has a signature “clean” spiciness that is gentle at first but gives a touch of quickly fading heat in your nostrils. Compared with real wasabi, fake wasabi can be hot and zingy too, but not as clean in the mouth.

That hit of heat you get when you eat wasabi is unmistakable. But what makes wasabi spicy? The spicy sensation of wasabi is derived from a chemical compound called allyl isothiocyanate, which is also present in mustard and horseradish.

Real wasabi is traditionally prepared by running the root in circles over a flat grater that acts like sandpaper, finely shearing the root down into a fresh paste and unleashing the allyl isothiocyanate, making the wasabi spicy!

In contrast, chili pepper’s type of spice hits the tongue directly and comes from the chemical compound capsaicin. Thus, the spiciness of wasabi tends to go up the nose as opposed to the spice of cayenne or chili pepper. 

If you want to enjoy the unique flavor of wasabi but find the heat overwhelming, there are ways to take the spice level down a notch or two. For starters, use it sparingly, in little dabs or spread thinly rather than thick dollops. If the pure wasabi is still too strong for your taste, you can try blending it with mayonnaise or soy sauce.

Not only is it a delicious accompaniment to sushi, but hon-wasabi is also full of vitamins and antioxidants, and offers a range of health benefits. Wasabi contains the main class of active compounds called isothiocyanates (ITCs), which give this root vegetable its range of health benefits, including antibacterial and anti-inflammatory properties. Helping to improve the immune system and to remove harmful toxins, it can even kill harmful food-borne bacteria; it’s that powerful! 

1. Boosts the immune system
2. Improves gut health
3. Helps with arthritis and bone-related issues
4. May reduce the risk of cancer
5. May reduce the risk of heart disease and protect heart health
6. Anti-inflammatory properties for joints and muscles
7. Antibacterial properties can kill food-borne bacteria
8. May help alleviate seasonal allergies
9. May help heal respiratory conditions
10. May promote fat loss

You must be thinking, “What is wasabi, some kind of superfood?!” Well, it might have a lot of health benefits, but remember that it comes with a very high price tag. Plus, let’s not forget that these health benefits may only apply to real wasabi. As only a small amount of hon-wasabi is used in imitation wasabi products, the health benefits are probably absent if you eat the fake kind. Read more about the health benefits of wasabi.

Bear in mind that wasabi is meant to complement the main dish not mask or overwhelm it. One of the original purposes of real wasabi was to moderate the fishiness of fish and help bring out its flavor. Knowing this can help you gauge how much wasabi to use. 

If you are eating wasabi with sushi, you should know that sushi chefs usually add the wasabi already. Since these highly trained chefs know how much to use, chances are it would be too much wasabi if you were to add any more. Eating wasabi pure, rather than mixing it with soy sauce or anything else, is usually recommended.

Dipping fish (such as sashimi) in soy sauce first, then adding wasabi on top before eating, is an acceptable way to use wasabi. Eating wasabi with soy sauce is also common when eating a bowl of seafood and rice. Be sure to mix in the wasabi thoroughly until it’s smooth without any lumps left.

Apart from soy sauce, vinegar and avocado are also sometimes mixed with wasabi. 

Wasabi is usually a condiment rather than a cooking ingredient, meaning you’re more likely to use it as a dip, dressing, or spread. Some people do actually cook with it, though, by stirring it into soup or a stew or mixing it into their marinade. In its powdered form, wasabi has also been used to coat finger food like French fries or peanuts.

Real wasabi is usually prepared just before eating because it does not have a very long shelf life. Wasabi usually starts to lose its flavor after about 15 minutes. If you really have to prepare some ahead of time, however, you can grate the wasabi rhizome and then freeze it immediately. Some people find it more practical to freeze-dry wasabi powder.

To tell the difference between real and fake wasabi, first check the texture of the wasabi paste. Thick and pasty wasabi is a sign that it is fake and made from horseradish (pureed to give a completely smooth texture). If the consistency is gritty (from being freshly grated), then it is more likely to be true wasabi from a wasabi plant stem.

Real wasabi is always served fresh because it quickly loses its flavor and sting once grated. At a high-end sushi restaurant, the chef will carefully grate the exact amount of wasabi to complement the sushi and balance the flavor of the fish. It is often placed between the rice and the sushi topping to preserve it as best as possible.

Although you can find so-called "wasabi" all over the world, it's believed that very few restaurants outside Japan serve authentic wasabi. Many restaurants in other parts of the world will create their wasabi from a mix of powdered wasabi, horseradish, and mustard. 

To know how to ask what's included in a dish or sauce, or tell someone that you have an allergy, read our guide to Japanese for vegans.

Wasabi allergy warning: Even in Japan, it is worth checking whether you're getting the real thing if you are allergic to mustard (マスタード), as this is an unexpected ingredient for many people.

So, to summarize, wasabi is best known as a condiment from Japan made from the underground stem of a wasabi plant. Real wasabi is served raw, in the form of a paste made from finely grating its stem.

The perfect conditions needed to grow the wasabi plant make it incredibly rare and expensive. Nevertheless, this traditional Japanese condiment is delicious, even if you have to settle for imitation wasabi to get a spicy mustardy kick. You can also always try to make your own wasabi!

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