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Wasabi is the pale green, sharply pungent condiment served with sushi, made by grating the knobby stem of a mustard-family plant from Japan. The short answer to the most common question: the green paste sold as wasabi is often not made only from that plant, because real wasabi is expensive and is often replaced with its cheaper relative, horseradish. This guide covers what real wasabi is, how to read a wasabi label, wasabi nutrition from USDA data for both the raw root and the prepared paste, why the heat hits your nose, and what the small amount of research does and does not show.
Peptide Labs does not sell wasabi or wasabi products. This article is general nutrition information, not medical advice.
Key Takeaways
- Real wasabi comes from Eutrema japonicum (also called Wasabia japonica), a mustard-family plant; the part that is grated is its knobby stem, which USDA lists as the root.
- Because real wasabi is expensive, wasabi products are often made partly or wholly with horseradish; the ingredient list tells you which.
- USDA lists the raw wasabi root with fiber, vitamin C and potassium, but the amount eaten with sushi is tiny.
- USDA's prepared wasabi entry has about 10% of the Daily Value for sodium in one teaspoon.
- Human research is limited to a few small studies, mostly of a wasabi extract supplement rather than the food.
What is wasabi?
Wasabi (Eutrema japonicum, often still called Wasabia japonica) belongs to the Brassicaceae, the same plant family as horseradish, mustard, cabbage and kale. The edible part is a thick, knobby stem, technically a rhizome, that grows at the base of the leaves; USDA’s nutrient database lists it as wasabi root. Fresh wasabi is grated into a fine paste just before serving.
In the intact root the pungent compounds are locked away. A 2001 spectroscopy study of wasabi and horseradish found the main sulfur compound in the whole root is sinigrin, and that breaking the cells converted it to isothiocyanates, the molecules that produce the bite. That is why wasabi is grated right before eating and why a whole root has little smell.
Real wasabi vs the green paste in most packets
Food scientists who developed a DNA test for wasabi products wrote in 2016 that, because of its high market value, original wasabi is often replaced by its cheaper close relative, horseradish. Their method was designed to detect exactly that kind of substitution. For shoppers, the practical check is the ingredient list, not the color or the word wasabi on the front of the tube.
- Ingredients are listed by weight. If horseradish appears before wasabi, the product contains more horseradish than wasabi, and some products may contain little or none.
- Look for the plant name. Products made from real wasabi usually list wasabi, Wasabia japonica or Eutrema japonicum near the top.
- Fresh rhizomes are the most direct way to taste real wasabi; some specialty grocers carry them for grating at home.
- Powders need reading too. The same label check applies to wasabi powders: see which plant is listed first.
A high or low sticker on its own is not proof either way. A DNA test like the one in the 2016 study is what reveals the mix inside a product, and both plants owe their heat to similar chemistry, so taste alone can mislead.
Wasabi nutrition: USDA values for the raw root
The USDA FoodData Central SR Legacy database has an entry for raw wasabi root (FDC 168583). The table shows 100 grams and USDA’s portion of one cup sliced (130 grams), with the percent Daily Value (%DV) based on the FDA Daily Values printed on Nutrition Facts labels. Keep the context in mind: the dab served with sushi is a few grams, so it adds only a small fraction of these numbers.
| Nutrient (wasabi root, raw) | Per 100 g | % DV | 1 cup sliced (130 g) | % DV |
|---|---|---|---|---|
| Calories | 109 | Not applicable | 142 | Not applicable |
| Carbohydrate | 23.5 g | 9% | 30.6 g | 11% |
| Fiber | 7.8 g | 28% | 10.1 g | 36% |
| Protein | 4.8 g | 10% | 6.2 g | 12% |
| Vitamin C | 41.9 mg | 47% | 54.5 mg | 61% |
| Potassium | 568 mg | 12% | 738 mg | 16% |
| Calcium | 128 mg | 10% | 166 mg | 13% |
| Magnesium | 69 mg | 16% | 90 mg | 21% |
| Manganese | 0.39 mg | 17% | 0.51 mg | 22% |
| Vitamin B6 | 0.27 mg | 16% | 0.36 mg | 21% |
| Zinc | 1.62 mg | 15% | 2.1 mg | 19% |
| Sodium | 17 mg | 1% | 22 mg | 1% |
Per 100 grams, the root carries more calories than most vegetables because it is denser and drier, with about 69 grams of water per 100 grams in USDA data. It also supplies fiber and vitamin C, a nutrient covered in our guide to vitamin C sources. USDA lists no total-sugars value for the raw root.
Prepared wasabi paste: sodium, sugar and calories
USDA also lists a prepared wasabi product (FDC 171831) in its sauces category. Its ingredients are not given, but its USDA numbers look very different from the root: per 100 grams it has 292 calories, about 11 grams of fat, 13 grams of sugars and 3,390 milligrams of sodium. The table puts it next to USDA’s prepared horseradish entry (FDC 173472) in USDA’s own teaspoon and tablespoon weights.
| Food (USDA FDC ID) | Amount | Calories | Sodium (% DV) | Total sugars | Fat | Fiber (% DV) |
|---|---|---|---|---|---|---|
| Wasabi, prepared product (171831) | 1 tsp, 6.5 g | 19 | 220 mg (10%) | 0.9 g | 0.7 g | 0.4 g (1%) |
| Wasabi, prepared product (171831) | 1 tbsp, 20 g | 58 | 678 mg (29%) | 2.6 g | 2.2 g | 1.2 g (4%) |
| Horseradish, prepared (173472) | 1 tsp, 5 g | 2 | 21 mg (1%) | 0.4 g | 0.03 g | 0.2 g (1%) |
| Horseradish, prepared (173472) | 1 tbsp, 15 g | 7 | 63 mg (3%) | 1.2 g | 0.1 g | 0.5 g (2%) |
Sodium is the number to watch. One teaspoon of the USDA prepared wasabi entry lists about a tenth of the Daily Value, and sushi is often eaten with soy sauce as well. Brands differ widely, so compare Nutrition Facts labels; our guide to lower-sodium foods explains how to read the sodium line.
Why wasabi stings your nose
Wasabi, horseradish and mustard share their heat chemistry. A 2015 study identified allyl isothiocyanate as the main pungent component in wasabi, and a 2004 paper in Nature showed that these isothiocyanates act on a sensory receptor called TRPA1. Chili heat works through a different receptor, TRPV1, which capsaicin activates, as our cayenne pepper guide explains. Allyl isothiocyanate is volatile, which is why many people feel wasabi as a rush up the nose rather than a lingering burn on the tongue.
Sushi is often served with pickled ginger and wrapped in nori; those are different plants with their own nutrition profiles.
Is wasabi healthy? What the research shows
Wasabi is a condiment, so its main nutritional role is flavor with little sodium when you use the real root. Research interest centers on its isothiocyanates, especially one called 6-MSITC (6-methylsulfinylhexyl isothiocyanate). A 2024 review in Nutrients found that 6-MSITC has been studied mainly in lab and animal work, with few human studies.
- Memory study: a 2023 double-blind randomized trial gave 72 healthy adults aged 60 and older a wasabi extract supplement or a placebo for 12 weeks; the wasabi group scored better on working and episodic memory tests. It was one small trial of a concentrated extract, not of wasabi as food, and it needs repeating.
- Lab studies: a 2000 lab study found allyl isothiocyanate slowed the growth of some food-poisoning bacteria and fungi in dishes. That does not show that a dab of wasabi makes raw fish safer to eat; food safety still depends on handling and storage.
- Real vs imitation: studies of wasabi compounds usually use real wasabi or purified extracts, so results may not apply to horseradish-based pastes.
Safety: sensitivity, allergy and a famous mix-up
For most people a small amount of wasabi is simply hot. A 2019 case report in BMJ Case Reports described a 60-year-old woman who ate a large amount of wasabi at a wedding, thinking it was avocado, and developed chest pain from takotsubo cardiomyopathy, a stress-related weakening of the heart muscle. The authors called it the first reported case; it is rare, but it shows why a spoonful of wasabi is not a joke.
- Wasabi and mustard are not among the nine major food allergens under US law, so they are not highlighted the way milk, wheat or soy are; read the full ingredient list if you react to mustard-family plants.
- Strong pungency can irritate the nose, eyes and throat, so start with very little, especially for children.
- If you suspect a food reaction, our elimination diet guide explains why testing should be planned with an allergist or other clinician.
- Chest pain, trouble breathing or swelling after eating anything needs urgent medical care.
Wasabi pairs naturally with other foods covered on this site, and our sibling guide to mushrooms nutrition covers another staple of Japanese cooking.
Frequently Asked Questions
Is the wasabi at sushi restaurants real?
Sometimes, but often not entirely. Real wasabi is expensive and is often replaced with horseradish. Ask the restaurant or check the ingredient list on packaged pastes.
What is wasabi made of?
Real wasabi is the grated stem of Eutrema japonicum. Many pastes and powders are made with horseradish, mustard and other ingredients, sometimes with a little wasabi.
Is wasabi healthy?
Wasabi adds flavor with few calories when you use the real root, and USDA lists fiber and vitamin C in it. The amount eaten is small, and human studies of its compounds are few and small.
How much sodium is in wasabi paste?
USDA’s prepared wasabi entry lists about 220 milligrams in one teaspoon, about 10% of the Daily Value. Brands vary, so read the label.
Why does wasabi burn your nose?
Its main pungent compound, allyl isothiocyanate, is volatile and activates the TRPA1 receptor on sensory nerves, so the vapors reach the nose quickly.
Is wasabi the same as horseradish?
No. They are related mustard-family plants with similar heat chemistry, but they are different species, and real wasabi is far more expensive.
Questions about a label? Contact us or read our Buyer’s Guide. Food comes first; follow the label and ask a healthcare provider before starting a supplement, especially if you take medicines, are pregnant or have a food allergy. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Last reviewed October 2026.
Related guides: Horseradish: Nutrition, Heat, Prepared Horseradish and Wasabi, Sushi: Nutrition, Raw Fish Safety, Mercury and Pregnancy, Nori and Seaweed: USDA Nutrition, Benefits, Iodine and Safety.