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Scientific name: Fucus vesiculosus L. and other Fucus species (Fucaceae)
Family: Fucaceae
Other names: Sea wrack, Kelp-ware, Black Tang, Bladderwrack, Kelp, Kelpware, Rockweed, Seawrack; German: Algen; French: Algue marine; Italian: Alga marina.

Brown seaweeds refer to species of Fucus, Ascophyllum, Laminaria and Macrocystis. ‘Kelps’ refer to species of Laminaria and Macrocystis, although kelp is often used in reference to species of Fucus.


Bladderwrack is a sea-plant which transforms inert inorganic substances from the sea into organic minerals capable of nourishing the human body. It is one of the richest sources of minerals (micro-nutrients) including chiefly iodine, sodium, manganese, sulphur, silicon, zinc and copper.

Chemical constituents

Mucilage, mannitol, alginic acid, iodine, potassium and a wide spectrum of trace minerals. Other constituents Various vitamins and minerals, particularly ascorbic acid (vitamin C).


Anti-hypothyroid, anti-obesic, anti-rheumatic, blood tonic, adaptogen, stimulates the circulation of lymph. It is also an endocrine gland stimulant, laxative, antibiotic and mild diuretic.


Traditionally, Fucus is very valuable in all cases of chronic acidosis; it has been used for lymphadenoid goitre (considered a wonder Herb for goitre), myxoedema (adaptogen), obesity (used for the specific purpose of reducing unhealthy fat in excessive adiposity), arthritis and rheumatism. Fucus is used to address several conditions such as thyroid disease, thyroxin deficiency, is advised as a specific remedy in the treatment of both exophthalmic and simple goitre. Unhealthy nutrition, listlessness, rickets, glandular ailments, general debility; to build up old broken-down constitutions. Obesity of low-thyroid function. Cases requiring increased body heat – hypothermia. Allays onset of arteriosclerosis by maintaining elasticity of walls of blood vessels. Beneficial to male and female reproductive organs, liver, bladder irritation, gall bladder and pancreas. Militates against onset of rheumatism and arthritis. Contains Vitamin K for prevention of strokes.

It can be applied externally in compresses or possibly plasters to use on the local inflammation or swelling that is associated with arthritis and rheumatism.

Tend to rid the system of useless waste matter and also restores chemical balance.

Medicinal Plants

Thallus (whole plant)


Dosages for traditional uses recommended in standard herbal reference texts are given below:

Capsules: 6 “O” capsules daily.
Teas: half teaspoon to each cup boiling water; infuse 15 minutes. Half to 1 cup.
Powder: Added to soups, salads; sprinkled on muesli or on a cooked meal.
Liquid Extract: 1:1, 25 per cent ethanol, 5-10 drops, three times daily.
Tincture: BHC Vol 1. 1:5, 25 per cent ethanol, Dose: 4-10ml.
Infusion: Dried thallus 5–10 g, three times daily.
Tablets: 300mg – 1 tablet, thrice daily after meals.

Pharmacological Actions

There is very little information documented for Fucus vesiculosus specifically. There are however pharmacological activities recognised for individual constituents and other brown seaweed species.


There is a lack of clinical safety and toxicity data for fucus preparations and further investigation of these aspects is required. Usually indication is taken as it pertains to kelp and other seaweeds. Hyperthyroidism has been associated with the ingestion of kelp and is attributable to the iodine content in the plant. Typical symptoms of hyperthyroidism (weight loss, sweating, fatigue, frequent soft stools) were exhibited by a 72-year-old woman following ingestion of a commercial kelp product for six months.


The iodine content in fucus may cause hypo or hyperthyroidism.

Anyone who is already consuming more than 1,000 mcg iodine per day probably will not benefit and may be harmed from bladderwrack supplementation.

Herbal Materia Medica fith edition, Michael Moore
Bartram’s Encyclopedia of Herbal Medicine, Thomas Bertram
American Materia Medica, Therapeutics and Pharmacognosy, Finley Ellingwood, M.D
Pocket Manual of Homeopathic Materia Medica, William Boericke

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