Hijiki (ヒジキ)

Hijiki (scientific name: Sargassum fusiforme, synonym: Hizikia fusiformis) is a kind of seaweed of the Class Phaeophyceae Family Sargassaceae Genus Sargassum. Hijiki grows near intertidal zones in rocky areas close to the choppy seashore.

It has been said traditionally that 'a person who eats hijiki lives longer,' and in connection with Respect-for-Senior-Citizens Day, September 15 is designated as Hijiki no Hi (Hijiki Day).


Areas in Japan where Hijiki is distributed are Honshu (the main island of Japan), the Shikoku region, the Kyushu region, and the Nansei Islands (the Amami-Oshima Island, the islands of Okinawa), and areas outside Japan are the Korean Peninsula and southern China.

Growing Environment
Hijiki is distributed in zones from lower areas of intertidal zones onto rocks on low-tide lines.

Hijiki used to be included in the Genus Hizikia, but is currently included in Genus Sargassum as a result of the Molecular Phylogeny conducted by Yoshida (2001).

Hijiki has a length of 50-100 cm. Stolons creep and adhere onto rocks. One to several main branches (stems) extend from stolons, and twigs and leaves sprout from main branches. Main branches are cylindrical and have a thickness of 3-4 mm. Leaves are in the shape of a spatula, and have saw-tooth edges.


Hijiki is mainly used as a foodstuff. Mostly sold as hoshi hijiki (dried seaweed). Processing methods are roughly divided into steam and dry methods called Ise hoshiki (a traditional steaming method) in which dried algae is rehydrated and then steamed and dried, and boiling and drying methods. The boiling and drying methods are further divided into methods exemplified by Boshu seiho (method of boiling and drying raw algae) in which raw algae is boiled and dried, and methods in which dried algae is rehydrated and then boiled and dried. Its color is brown to brownish while it is alive, but turns black as it is processed. Hijiki no Gomoku ni' (stewed hijiki mixture) prepared by dehydrating hoshi hijiki and then boiled with soy sauce, sugar, and the like is a popular way of eating hoshi hijiki. In recent years, it is used in wide varieties of foods such as salad, vinegared food, and Tempura, in addition to Hijiki Gohan (boiled rice with hijiki, vegetables and meat or mixed rice and stewed hijiki mixture).

Hijiki is generally collected with a sickle in rocky shores by fishermen and woman shell divers during low tide in the spring tide from March to May. In some areas, budlets of hijiki are collected during the mid-winter (November to February).

Thin and long stem parts of hijiki and extruding parts such as leaves and buds are separately processed into products. Products of separated stem parts are called naga hijiki (long hijiki, the stem of the plant), kuki hijiki (long hijiki, the stem of the plant), ito hijiki (long hijiki, the stem of the plant), and the like. Products of separated bud parts are called me hijiki (bud of hijiki, the leaf of the plant), hime hijiki (bud of hijiki, the leaf of the plant), kome hijiki (bud of hijiki, the leaf of the plant), and the like.

Naga hijiki and me hijiki may be chosen according to its method of cooking or preference.

Movements Related to Inorganic Arsenic Content Percentage

In October 2001, the Canadian Food Inspection Agency reported that hijiki contains a higher percentage of carcinogenic inorganic arsenic than those in other seaweeds, and recommended avoiding hijiki. This is supported by multiple surveys, and food safety authorities of the United Kingdom, Hong Kong, and New Zealand announced the same recommendation.

The Ministry of Health, Labour and Welfare of Japan, on the other hand, announced their opinion in July 2004 that in view of the arsenic contents in the results of the surveys, the provisional tolerable weekly intake announced by the World Health Organization (WHO) would not be exceeded unless 33 g or more (of dehydrated hijiki, in cases of a 50-kg adult) was regularly taken into per week, and that in view of the current average intake of Japanese people, the health risk was not likely to rise in cases of normal consumption. They also announced that no health damage caused by arsenic contained in seaweed was reported.

Rank in Protection

The Okinawa Prefecture version of the Red Data Book
Near Threatened

[Original Japanese]