Wasabi (Wasabia japonica) is an edible plant member of the Cruciferae family, which includes cabbage,
Wasabi's culinary popularity and chemical bioactivity make it valuable medicinally and industrially. Demand for wasabi has created a relatively short supply, higher prices, and new commercial opportunities. These new opportunities include research and development of cultivation technologies, particularly in Canada, and exportation from Japan of seiyo wasabi, or Western wasabi—imitations made of horseradish (Cochlearia armoracia). Western and Japanese wasabi are both highly prized.
Wasabi is a perennial, root-like rhizome that is cylindrical in shape. A brownish-green skin covers its pale green flesh. The plant grows to about 18 in (46 cm) in height and produces leaves on long stems from the crown of the plant. As the plant ages, the leaves fall off and a rhizome, or creeping underground stem, is formed, from which new buds arise as modified stems. The modified stem is the part of the plant that is used. The highest quality wasabi, whose translated name is mountain hollyhock (also known as sawa wasabi), thrives on cool water. It grows along the edges of cold mountain streams. When cultivated, rather than wild-crafted (harvested randomly from its natural growing places), it is grown on tree-shaded, terraced gravel beds covered by a thin layer of cool running mountain water or on artificially shaded gravel ridges formed in larger river beds. A lower quality wasabi (oka wasabi) is grown in fields. There are two varieties of wasabi, Daruma—considered to have a more attractive appearance—and Mazuma—considered to have more heat. Wasabi is described as being "hot and fiery without burning," which changes to a sweetness that lingers in the mouth.
Historically, wasabi has been consumed as a condiment, used similarly to horseradish or mustard. Its pungent flavor and aroma may add a piquant flavor to sushi, marinades or sauces, and rice, noodle, and fish dishes. In Japanese restaurants across North America, sashimi and sushi may be served with a small mound of grated wasabi or wasabi paste. Nontraditional uses include adding wasabi to mashed potatoes, tuna sandwiches, or blending it with soy sauce. One source included it in a recipe for a unique Bloody Mary. Wasabi leaves marinated in sake, brine, or soy sauce, are eaten with a bowl of rice.
In addition to its flavor, wasabi has another benefit. Traditional Japanese cuisine includes raw fish, which is a potential source of parasites and bacteria. Wasabi's antiparasitic,
antimicrobial, and antibiotic abilities may be preventive against food poisoning. One source points specifically to wasabi's effectiveness against the Anisakis parasite. Another study, comparing the antibacterial activity of different foods against Escherichia coli (E. coli) and Staphylococcus bacteria, found that cruciferous plants possess antibacterial activity, with the highest activity found in wasabi (rhizome).
Other studies found that wasabi may be effective against the tooth-adhering ability of the bacteria Streptococcus mutans, thus inhibiting dental plaque and decay. Of special note are the numerous studies demonstrating wasabi's effectiveness against stomach cancer cells. One study found the induction of stomach cancer in rats was suppressed when they were given wasabi. The risk of hormone-related malignancies, such as breast and prostate cancer, may also be lowered. Some researchers believe that the cruciferous vegetables help the body eliminate excess endogenous (produced from within) and exogenous (produced from without but ingested or
Other medicinal benefits attributed to wasabi include its effectiveness against diarrhea, blood clots, inflammation, and asthma. Its pungent aroma may help relieve sinusitis and bronchitis. Although the amounts absorbed from culinary use may be negligible, wasabi reportedly also contains potassium, calcium, and vitamin C.
Industrial applications of wasabi under investigation include its usefulness in the development of other antibiotics, due to its own antibiotic qualities; its effectiveness as a fungicide against the blackleg fungus that threatens plants commercially valued for their oil, such as rape-seed and canola; and its possible use as an effective alternative to chemically toxic wood preservatives.
Wasabi is most commonly found in powder or paste form. However, due to the scarcity and price of high quality wasabi, many of these preparations—including imports from Japan for retail sale and those served in Japanese restaurants—are imitations made of horseradish, mustard, a starchy binder, and coloring. Wasabi paste may be made from a powdered wasabi by adding water, and letting it stand 10 minutes to allow the flavor and heat to develop. One source noted that the powder may be safely stored in a cupboard, but recommended refrigerating the paste. A salad dressing may be made by combining 3 tablespoons of rice wine vinegar, 1 tablespoon honey, 1 teaspoon wasabi paste, 1 teaspoon soy sauce, and 1/2 teaspoon sesame oil.
Traditional wasabi is prepared freshly for each use, as its volatile oils are quickly dissipated. It is recommended that individuals select a fresh, cool, and succulent rhizome with nice color. It should be rinsed under cool water with a vegetable brush, cutting a fresh surface below or above the leaf node (a distinctive ridge as on bamboo stems). While maintaining a 90-degree angle to the grating surface, the wasabi should be grated in a circular motion against a traditional sharkskin, ceramic, or stainless steel grater. (It is not necessary to peel the wasabi rhizome before grating it.) Then it is gathered into a ball and allowed to sit momentarily at room temperature. It is best used within 15 to 20 minutes.
One source notes that wasabi products are often found in large grocery stores that sell Asian food products and ethnic condiments; Asian markets; fish markets; gourmet shops; and other alternative marketplaces. Prices are similar to other specialty condiments of equal quality.
Wasabi should not come into contact with the eyes or nasal passages.
Due to its anti-inflammatory, antibiotic, antibacterial, antiparasitic, anticoagulant, and anti-asthmatic effects, the use of wasabi may magnify the effects of certain pharmaceutical drugs used for similar purposes. People with ulcers, esophageal reflux, kidney disorders, gastrointestinal disease, or those using hormone replacement therapy, are advised to consult with a healthcare professional before using wasabi.
Due to its liver and gallbladder stimulating effects, eating wasabi may cause gastrointestinal disturbances, including diarrhea and nausea.
One source notes that wasabi has possible interactions with anti-inflammatory analgesics, anesthetics, thyroid medications, corticosteroids, diuretics, and high blood pressure medications. This may be due in part to confusion with horseradish species. No other Wasabia japonica-drug interaction references are noted.
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Lee Ann Paradise
Katherine E. Nelson, N.D.