Due to the geographical nature of Japan, with 73% of its land being mountainous and 1% of its territory consisting of water, seaweed is a very important part of the Japanese diet. Together with being high in vitamins and minerals such as Vitamin C, Calcium and Iron, it is abundant and inexpensive.

Furthermore, as a result of the nature of the sea surrounding the Japanese archipelago, there is a wide variety of seaweed available, as seaweed (other than nori) flourishes in water where there are rapidly flowing currents. The continuous flow of water ensures that the water is clean and results in tasty seaweed full of vitamins and minerals.

Did you know?

There are seasons for seaweed. The majority of seaweed is ready to harvest in the spring but konbu is ready to harvest in the winter and only grows in cooler waters, such as around Hokkaido. In fact, the tastiest konbu comes from the coldest areas.

Seaweed is good for balancing your diet as it is an alkaline food and the majority of other foods are acidic. Therefore, it can help to decrease problems which arise from a high level of acidity such as heartburn.

The longest growing seaweed is Naga Konbu which is grown in Hidaka, a region in Hokkaido, and can grow in excess of 20 metres.

The Range of Seaweeds and How They Are Eaten:


Hijiki seaweed

A black seaweed which is bought dried and needs to be reconstituted in plenty of water for about an hour and washed thoroughly before use.

It develops a stronger flavour being cooked in oil and is served stir-fried and boiled with carrots, and either abura-age or chicken, and seasoned with soya sauce.

Alternatively, it can be mixed with mashed up tofu and other ingredients such as carrot and shiitake mushrooms, and steamed in a pocket of abura-age.


Kanten seaweed

Also known as agar agar, this seaweed is tasteless and is not eaten in its own right. Instead, it is boiled and its extract is used as a gelling agent.

Kanten is rich in fiber but has zero calories and is believed to help lower cholesterol and blood pressure.


Konbu seaweed

Sold in dry strips which have a white covering; this is the Umami (the essence of the flavour, “savoury”). This seaweed is reconstituted by being soaked, or heated in water (it should not be boiled).

A strong tasting seaweed which is used to make dashi, the standard Japanese soup stock, together with bonito flakes. The two flavours of konbu and bonito complement one another to produce a much rounder flavour than they have individually. In the same way, there is a tradition of using konbu to wrap around fish in order to impart its flavour on the fish. This is called, “Kobujime”.

The best tasting konbu is Rishiri Konbu named after the area it is grown in Hokkaido, Rishiri-tou. The second best is Hidaka Konbu from Hidaka, Hokkaido. The majority of konbu grows in Hokkaido at a length of between 60cm and 2m.

Konbu is a difficult food to digest and must therefore be cooked for a long period of time in order for you to be able to eat it. Rather than being eaten in its own right, it is valued for its depth of flavour in soups and Japanese stews (nabe).

The shavings of konbu, called “Tororu Konbu” are used to flavour tsuyu (a dipping sauce) or around rice balls (onigiri). They can sometimes be used to replace nori seaweed when making sushi.

It is also eaten as tsukudani, a dish where the konbu is boiled for three hours in soya sauce, mirin and dashi.

Furthermore, konbu can be cut up into small strips (after cooking) and pickled with vegetables.


Mozuku seaweed

A dark brown seaweed eaten with rice vinegar as a starter or palate refresher.

Mozuku is harvested in the spring and 90% of the mozuku eaten in Japan is produced in the southernmost islands of Okinawa. Research is currently being undertaken into its anti-cancer properties.


Nori seaweed

Also known as “Laver” and used to make Welsh Laver Bread.

This seaweed only grows in sheltered waters in a similar manner to moss, adhering itself to other objects in the sea. It is now farmed using nets for it to grow on.

Nori is sold in sheets with a very similar consistency to rice paper and its most well-known use is to make sushi rolls (maki-sushi).

It can also be eaten as tsukudani (see the konbu section above), or can be dissolved in water and mixed with kanten to form a firm shape which is then used as a decoration for sashimi.


Ogonori seaweed

A light and delicate seaweed, ogonori is sold preserved in salt and refrigerated.

This seaweed is only ever eaten cold, either as a salad vegetable, or served with sashimi. We need one more sentence here.


Tosaka seaweed

Tosaka comes in three different colours; red (aka-tosaka), green (ao-tosaka) and white (shiro-tosaka).

It is sold preserved in salt and refrigerated.

Like ogonori, this seaweed is eaten cold, in a salad or served with sashimi.


Wakame seaweed

Wakame is sold either fresh (and can be eaten as it is) or in a dried format. To rehydrate it takes an hour and requires lots of water. Using around 1 litre of water per 10g of wakame will give it the space to expand fully.

A very versatile seaweed which can be eaten hot in soups, cold in salads, with sashimi or as sunomono (a vinegar based dish).

The best time to eat it is in the spring at the same time as takenoko (bamboo shoots) are out and a typical, seasonal dish is Wakatake which is the new, bright green wakame and takenoko shoots served in a clear soup (suimono).

Seaweed Salad Dressing Recipe

Seaweed can be used to make a seaweed-only salad or can be mixed together with other salad leaves.

Combine vinegar (preferably rice vinegar), water, and a small amount of oil with soya sauce and seasoning to taste.

The dressing needs to consist of only a small amount of oil. We recommend trying a vinegar-only dressing.

Citrus juices (e.g. orange, lemon, lime, yuzu) can also be used to replace half the amount of the vinegar but citrus juice impairs the vinegar’s characteristic of adhering to the seaweed.