Skip to content
Soul of Herbs
← Back to herbs

Wasabia japonica

Wasabi

Generally recognised as safe

Other names: Eutrema japonicum, Japanese horseradish

Wasabi of cold spring gravel in mountains; culinary rhizome.

Perennial from rhizome; kidney-shaped basal leaves.

Family
Brassicaceae
Plant type
Perennial herb
What the safety levels mean (expand legend)
  • Generally recognised as safe. Often a common herb with reasonable harvest and use; still read the specific warnings on the card.
  • Information. Primarily informational — details in the text and warnings below matter most.
  • Caution. Needs extra care (dose, duration, sensitive groups, interactions).
  • Risky. Significant risks — verify sources, contraindications and professional guidance.
  • Not for home experimentation. Not suitable to experiment with at home without knowledge and certainty.
  • High risk for internal use. Particular risk with internal use (e.g. alkaloids); avoid prolonged or irresponsible dosing.
  • Not specified. Level not filled in yet — rely on individual warnings and links below.
Wasabi — plant habitus (Wikimedia Commons).

Photograph on Wikimedia Commons (Public domain).

Plant habit

Quick overview

A practical summary; details are in the sections below.

Safety grade
Generally recognised as safe details
Scientific sources on the card
Yes — sources are listed with claims Science section
When and what to harvest
  • Rhizome — January–December
Full harvest section
Processing methods

Culinary use, Powder

All methods and recipes on the card
Topics and symptoms

Digestion, Stuffy nose & colds

Topics section, Symptoms overview

Identification and mix-ups

Habitat and habit differ from watercresses.

Possible mix-ups and risks

Horseradish when material is uncertain.

Similar herbs

  • Horseradish

    Horseradish is the stand-in for most 'wasabi' on the market: a white root with a sharper, coarser heat. Real wasabi is a green rhizome with a delicate, fast-fading heat and a sweet finish.

Topics and symptoms

More topics are in the symptoms and topics overview.

Geographic occurrence

  • Japan

    Common (expected wild occurrence in the region)

Harvest

  • RhizomeJanuary–December

    celoročně

    Region: Japan

    Notes: The rhizome (strictly a thickened stem) is harvested 18–24 months after planting, from the cold running water of mountain beds (sawa-wasabi) all year; leaves and stalks are picked continually as a vegetable.

Storage

  • Refrigeration(Rhizome)

    A fresh rhizome keeps 2–3 weeks in the fridge wrapped in a damp cloth inside a bag; change the cloth every few days. Grate just before eating, the heat fades within 15 minutes.

    Moisture:
    Must neither dry out nor sit in water.

Processing methods on this herb card

  • Culinary use(Rhizome)Suitability: High suitability

    Cooking, baking, seasoning as food — general category without therapeutic claims.

    Full method description (from the catalogue)

    Culinary use covers herbs as ingredients in dishes, drinks, or spice mixes. This overview does not evaluate medicinal effects — only reminds you about species intent, allergies, and heat treatment where needed (e.g. some fruits or plant parts).

    Combining with alcohol, sugar, or long cooking changes outcomes; verify culinary sources.

    Traditional context for this method: yes·Scientific context for this method: no

    Freshly grated wasabi

    About 5 minBeginnerScience profile

    Open recipe →

  • Powder(Rhizome)Suitability: Low suitability

    Finely ground dried herb; dosing and solubility depend on species.

    Full method description (from the catalogue)

    Powder increases surface area for liquids or food. Home milling needs a clean grinder and control of fineness; very fine powder may clog tea filters.

    Store airtight against moisture and pests.

    Traditional context for this method: no·Scientific context for this method: no

    Commercial 'wasabi powder' is mostly horseradish with mustard and dye, not this plant.

Traditional / spiritual use

Kept separate from science — entries are cultural or symbolic, not medical advice.

  • Wasabi from Utogi — the spice a shogun kept for himself

    General

    Historical mentionFolk useHerbal lore

    Wasabi cultivation began around 1600 in the mountain village of Utogi near Shizuoka; tradition has it that Tokugawa Ieyasu tasted the local wasabi, declared it a treasure and forbade its export from the province. Wasabi became paired with Edo sushi in the 19th century through the folk belief that it 'kills the poison' of raw fish. A historical record, not evidence of effect.

    Form:
    koření k syrové rybě, dar šógunovi
    Claim strength:
    Historical mention
    Source note:
    Tradition of the Utogi growers (Shizuoka), Edo culinary history; laboratory antimicrobial data exist, clinical data do not.

Scientific notes

Each claim lists a study type and a source (URL or DOI) where available. Dose notes from the literature are informational only.

How to read evidence strength and study type labels

Labels summarise how the catalogue entry is tagged — they are not a medical verdict on efficacy. For every row, read the summary, limitations and source link.

Evidence strength

Evidence level not specified
The author did not grade the record; judge from the summary, limitations and source link.
Narrative / orientational literature
Descriptive or expert literature without controlled group comparison — context rather than proof of effect.
Weak evidence
Study or conclusion with major methodological limits; treat only as a pointer for further reading.
Preliminary findings
First or smaller studies — interesting direction, not the final word on efficacy or safety.
Moderate strength of evidence
Moderate strength by study design; sample and context limits still apply.
Stronger evidence
Stronger design or consistency of results within the study's stated limits.
Review article
A review summarises multiple sources; quality depends on review method and field.

Study type

Narrative / expert text
Expert text or overview without a classical study design.
In vitro study
Cell culture or test-tube experiment — does not show an effect in the body.
Animal study
Animal model — transfer to humans is not automatic.
Observational study
Observing groups without random treatment assignment; confounding is possible.
Clinical trial
Human clinical trial; sample size and control group matter.
Randomised controlled trial
Randomised controlled trials are among the stronger designs when well conducted.
Review study
A review aggregates multiple papers — quality depends on selection rules.
Systematic review
Systematic review with explicit search and selection methodology.
Meta-analysis
Statistical pooling of studies; outcome depends on input data and heterogeneity.
Regulatory assessment / monograph (EMA, WHO…)
Regulatory body summary for a herbal product — different context from a single RCT; often about products, not home tea.
Expert monograph (herbal preparations)
Structured literature summary for a plant or drug — quality depends on author and edition year.

Images

The main photo is in the card header. More images will appear here when available.

Safety

What the warning types mean

The type on each warning helps group themes — it does not replace the separate severity badge.

Internal use
Risks from swallowing, extracts, duration of use or concentration for internal use.
Interactions / medicines
Possible effect on medicines or concurrent treatment — check sources and a professional.
Raw plant parts
Raw, unripe or poorly prepared plant parts can be dangerous.
Toxins and regulation
Toxic constituents or regulated compounds (e.g. in distillates).
Contact with the plant
Skin or mucosa irritation from contact with fresh plant or sap.
Allergy
Allergic reactions, often linked to family sensitisation.
Harvesting and contamination
Contamination, species mix-ups or harvesting from unsuitable places.

No structured safety records yet.