Created for expats living in Japan

What Is Japanese Seaweed? A Guide to Japan's Essential Ingredient

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Seaweed is considered an integral part of the Japanese diet and is widely used in Japanese cuisine. There is a range of potential health benefits to seaweed, including its concentration of fiber and minerals, all while staying low in calories. There are also many varieties of seaweed products to choose from in Japan, and many ways to use them. Here we will explore some of these varieties, and how they may be beneficial for your diet.

What Is Seaweed?

Seaweed simply refers to the wide range of marine plant life that grows in various bodies of salt water. It can be in the form of algae or marine-based plants. Edible seaweed is also sometimes referred to as sea vegetables. Seaweed can be categorized in a number of ways, with one of the most common being by color. These include red, brown, and green.

While seaweed can seem an unusual ingredient for some foreigners who have yet to try the breadth of Japanese cuisine, the ingredient has actually been used throughout history by countries in both the Eastern and Western worlds. For true beginners to the world of seaweed, the best thing to do is to put aside any biases or preconceptions around seaweed and consider it as just another vegetable.

Types of Seaweed

As we have mentioned, there are many varieties of seaweed common to Japanese cuisine. Here we will look at some of the most popular types. 

Nori (のり)

Nori is perhaps the most well-known type of seaweed outside of Japan. Usually sold in thin dry sheets, it can be used in a range of ways. Nori is the variety of seaweed generally used in sushi and onigiri (rice ball) making, which has led to its popularity overseas. Seasoned nori can also be bought and eaten as a snack, along with nori chips (toasted and salted nori). When cut into small strips, it is also a popular garnish for many Japanese dishes.

Nori is a common starting place for foreigners delving into the world of seaweed — it is somewhat familiar as a part of sushi, it serves as a delicious snack, and seasoned nori such as with salt or soy sauce is familiar and easy to eat.

Wakame (わかめ)

Wakame is another popular type of seaweed in Japan. It can be bought fresh during the harvesting season, but it is most commonly available dried and is later rehydrated while cooking.

This seaweed is often used in side dishes. These include seaweed salads,  , and the Japanese staple of  . Its light, tender flavor makes it a great addition to side dishes, which aim to enhance the meal rather than taking the spotlight. Wakame is also very low in calories but may help energy levels, and so it is often eaten to aid in weight loss.

Kombu / Kelp (昆布)

Kombu, also known as kelp, is one of the most versatile varieties of seaweed used in Japanese cooking. Mostly harvested in Hokkaido, it is similar to wakame in that it is usually sold dried and later rehydrated.

Kombu is a key ingredient in dashi broth, a base ingredient of many Japanese dishes, including miso soup and ramen. The kombu helps provide the rich umami flavor that makes dashi a real powerhouse of Japanese cuisine. Kombu can also be used in tea and soups; caramelized in soy sauce, sugar, and sake; and used as an accompaniment to rice, salads, and onigiri. It is known to be high in calcium and iron, which helps add to its popularity.

Hijiki (ひじき)

Hijiki is one of the lesser-known varieties of seaweed outside of Japan, but it is very popular in Japanese home cooking. This is a variety of brown seaweed, found along rocky coastlines. It is also sold dried, in a form that looks like small branches or tea leaves.

Much like other seaweed, hijiki must be rehydrated before eating. A popular dish is to simmer it in soy sauce and mirin and serve it as part of a salad. The salad often also consists of carrots, beans, tofu, lotus root and various other ingredients. Hijiki can also be used in soups and stews. It may have similar health benefits to many other types of seaweed, and is believed to be beneficial to hair and skin health.

Mozuku (もずく)

In contrast to the kombu of Hokkaido, mozuku is almost exclusively harvested in Okinawa. It is sometimes considered a superfood, along with many other Okinawan staples.

Mozuku has a unique stringy texture and is generally served with vinegar as a side dish. It can be bought either prepackaged with the vinegar or unseasoned. In Okinawa, it is also included in a range of other dishes, such as soups, stir-fries, stews, and more.

Where to Buy Seaweed in Japan

In Japan, most supermarkets stock a variety of seaweed products, since it is considered a key ingredient in many dishes. Convenience stores also often have a limited range of products. Depending on the type of seaweed you want to buy, you will need to go to different departments within the supermarket, including the refrigerated section (often near where tofu and natto is sold); the fish section, which carries fresh seaweed; and the dry ingredients section, where you can find all forms of dried seaweed, including nori.

For a more unique experience, there are specialty stores that focus on creating top-quality seaweed-based foods. These can include nori snacks with different seasonings or dashi broths using different types of kombu, among others.

You can also purchase them online via Amazon Japan. 

Make Seaweed a Gateway to Exploring Japanese Cuisine

Anyone who has visited Japan or eaten Japanese food frequently will understand how important seaweed is as a component of Japanese meals. The many varieties of seaweed allow for various tastes and textures to be explored while still using a healthy ingredient. For more information on Japanese ingredients like rice, natto, and more, be sure to check out our comprehensive Japanese food guides.