In Northern Hemisphere gardens, fall is a busy time. The perilla (a mint-family herb grown for its leaves and seeds) gets cut down, and beds are raked smooth for planting garlic. Around the same time on the coast, ropes seeded with young sea mustard are lowered into the sea. Koreans call this seaweed miyeok, and it's the same plant Japan calls wakame. In Korea, people eat miyeok-guk (sea mustard soup) on their birthdays and after giving birth. This seaweed also appears by name in a medical text written more than 400 years ago.
Haechae (海菜), as Recorded in the Dongui Bogam
The Dongui Bogam (Treasured Mirror of Eastern Medicine), a Korean medical classic published in 1613, lists sea mustard as haechae (海菜, "sea vegetable") in its section on vegetables (菜部). It gives the Korean name as "meoyuk," an old word for miyeok. The original text describes haechae as cold (寒) in nature, salty (鹹) in taste, and nontoxic (無毒).
The text also notes the seaweed's color. Fresh from the sea it is green, but once it is harvested and dried it turns purple, so it also went by a second name, jachae (紫菜, "purple vegetable"). Whoever wrote this had clearly seen the seaweed both as it came out of the water and after it dried. It grows in the sea, yet the text files it with the vegetables. That suggests people even then thought of miyeok as a vegetable for everyday side dishes.
This is what an old medical text recorded. It does not reflect the judgment of modern medicine. You can read the original passage with our explanation in the Dongui Bogam entry on meoyuk (海菜).
Side by Side with Modern Analysis
Modern analyses of sea mustard focus mainly on the following compounds.
- Alginic acid: a polysaccharide characteristic of brown algae
- Fucoidan: a sulfur-containing polysaccharide found in brown algae
- Iodine: a mineral the seaweed absorbs from seawater and concentrates
- Fucoxanthin: a carotenoid pigment found in brown algae
In some places the old record and the modern analysis agree. The salty taste the Dongui Bogam noted is consistent with the finding that brown algae concentrate minerals from seawater. The old text described the change in color from what its authors could see. Modern analysis has since named the pigment that gives brown algae their color: fucoxanthin.
In other places they differ. "Cold in nature" is a category from traditional Korean medicine, so a chemical analysis has nothing to match it with. Alginic acid and fucoidan, on the other hand, appear nowhere in the old record. Modern analysis credits these polysaccharides for sea mustard's slippery texture and for the way it thickens a broth. These analyses only describe what the seaweed contains. They say nothing about preventing or treating disease.
Iodine is a mineral the body uses to make thyroid hormones. But analyses show that the iodine content of sea mustard varies widely depending on where it grew, which part of the plant is used, and how it was dried. Even for the same kind of sea mustard, the amount of iodine can't be reduced to a single number. If you're being treated for a thyroid condition, talk with your doctor before you start eating a lot of sea mustard every day.
Sea Mustard from the Sea, Its Companions from the Garden
Sea mustard (Undaria pinnatifida) can't be grown in a garden. It's a brown alga native to the coasts of the northwestern Pacific, and in the waters off China, Korea, and Japan it is farmed mostly on suspended ropes. In the Northern Hemisphere the ropes go into the sea in October and November, and the harvest runs from January through April of the following year. You'll find more on timing and composition in the sea mustard entry in our Crop Guide.
What your garden can supply are the vegetables that go with it. The perilla oil used in miyeok-guk is pressed from perilla seeds. The cucumbers in chilled sea mustard soup and the garlic in stir-fried sea mustard stems can also come from your garden. Garlic you plant this fall will be ready early next summer, and cucumbers come in during summer. Dried sea mustard keeps for a long time, so bring some out when your garden vegetables are ready.
Ways to Enjoy It with Garden Vegetables
- Miyeok-guk (sea mustard soup): Sauté rehydrated dried sea mustard in perilla oil, then add water and simmer. Sautéing some beef along with it makes a richer broth. A pinch of salt while sautéing helps the seaweed hold its shape.
- Miyeok-naengguk (chilled sea mustard soup): Add julienned cucumber to rehydrated sea mustard, then pour in vinegar and cold water. The tartness covers the seaweed's briny smell. For a cleaner taste, boil the water ahead of time and let it cool.
- Miyeok-julgi-bokkeum (stir-fried sea mustard stems): Rinse salt-cured sea mustard stems in cold water several times to wash out the salt. Then stir-fry them with garlic over high heat. If you cook them too long they release water and turn limp, so keep the stir-fry short.
Why not start today? Soak some dried sea mustard in cold water, sauté it in perilla oil, and cook a pot of miyeok-guk.
