Hai Zao seaweed, Hijiki - Sargassum Fusiforme (Sargassaceae)

Medicinal Use of Hai Zao, Hijiki – Sargassum Fusiforme (Sargassaceae)


Brown seaweed (alga) with long thin fronds.

Habitat & Cultivation

Hai zao is found along the coastlines of China and Japan, where it is often seen floating in large masses. It is gathered throughout the year.

Part Used

Whole plant.


Hai zao contains polysaccharides, alginic acid, and significant levels of potassium and iodine.

History & Folklore

Wang Tao, an 8th-century Chinese physician, recommended hai zao for goiter (an enlargement of the thyroid gland due to iodine deficiency). Hai zao is eaten as a vegetable in Chinese and Japanese cuisine.

Medicinal Actions & Uses

Hai zao is used in a similar way to its European counterpart, the seaweed bladderwrack, or kelp (Fucus vesiculosus). In Chinese medicine, it is given principally to treat thyroid problems caused by low iodine levels within the body. The herb also helps to combat other thyroid conditions that produce enlargement of the gland, for example Hashimoto’s thyroiditis. Hai zao is prescribed to treat cases of scrofula (enlargement of the lymph glands in the neck due to tubercular infection) and edema (fluid retention).


Chinese research indicates that hai zao has anti-fungal and immunomodulating activity.

Related Species

In Chinese medicine, S. fusiforme is used interchangeably with S. pallidum.


Do not take hai zao for thyroid problems without professional supervision.