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Fucus et Ascophyllum


Fucus are common algae that develop in the mid-tidal zone , they support regular emersion periods twice a day.
These are perennial algae from temperate and cold seas (there are none in the Mediterranean sea).

They cling to the rocks by a very strong adhesive disc by which they can partially regenerate.

These are dioecious species whose gametogenesis patterns resemble those of animals, hence the classical explanations for the reproduction of vesicular fucus in secondary classes.

The fucus is in clumps of banded strips, dichotomes and there is the presence of floats (aerocysts) along the rib.

In France, we find mainly the vesicular fucus, Fucus vesiculosus, and the Fucus serratus with slightly serrated straps.

Ascophyllum nodosum, or black wrack, very close to the fucus, is also common in the mid-tidal zone of the North Atlantic coast where the sea is rather cool, this yellow-green algae when it is wet blackens at the desiccation.

Ascophyllum nodosum can be dense and completely cover rocks in sheltered areas.


For about twenty years the fucus, and especially Ascophyllum nodosum, are in strong regression almost a quasi disappearance on certain parts of the Brittany coasts where they were very abundant.

The same regression is also observed on the coasts of UK.

Intense predation by limpets (patella vulgata) is one of the explanations proposed for this regression, but climate change and coastal water pollution may be directly or indirectly.

Fucus serratus Fucus serratus


Fucus and Ascophyllum nodosum have similar chemical compositions, but quite variable depending on the time of year and the geographical area.

Average composition for 100g dry fucus:

- Water: 10 to 15 g
- Carbohydrates: 10 to 15 g (including mannitol)
- Lipids: 1 to 5 g
- Proteins: 7 to 15 g
- "Fibers" not assimilable: 45 to 50 g (including fucans and alginates more present in ascophyllum)
- Polyphenols (including phlorotannins): 3 to 10 g
- Sodium (4 to 5 g), magnesium (1 to 2 g), potassium (3 to 4 g), calcium (1 to 3 g)
- Iodine: 20 to 100 mg for fucus, 30 to 174 mg for ascophyllum
- Presence of metals and trace elements in particular: iron, copper, zinc, phosphorus, nickel, strontium, arsenic but also selenium, antimony, cadmium
- Vitamins: 50 to 200 mg of vitamin C in fresh seaweed; in the dried algae presence of vitamin B group, beta carotene, vitamin E and K.

From a pharmacological point of view, fucus and ascophyllum nodosum are interesting for their content of assimilable iodine, fucans, alginic acid, phlorotanins and mineral salts .


Iodine is necessary for the proper functioning of the thyroid and therefore the metabolism in general.
The amount necessary for the proper functioning of the body is estimated at 100 to 150 micrograms of iodized salt (potassium iodide) per day, a very small amount (1/10 of mg).

In the absence of iodine the thyroid does not work well, a goitre or goiter can develop which can be accompanied by many physical and psychic disorders (cretinism), conversely too much iodine in the food can eventually artificially increase the thyroid activity inducing nervousness, slimming, cardiac rhythm disorders.


The typical polysaccharides of fucus are fucans (or fucoidans): sulfated polysaccharides (polymers) present in the intercellular matrix.
They consist mainly of L-fucose, xylose and glycuronic acid.

Humans can not digest (assimilate) fucans unlike ruminants and even horses.

Fucans (or fucoidans) are highly studied especially in Asia.
They are found in the majority of brown algae (including laminaria) and they pose many problems for pharmacologists because it is difficult to obtain fucans with the same composition, it is generally a mixture of fucans with various structures.

Fucans have different properties:

-anticoagulant in the manner of heparin,

- inhibitors of the inflammatory reaction by acting in particular on the behavior of leukocytes,

- interesting in the fight against cancer: inhibitor of angiogenesis (the creation of blood vessels to irrigate the tumor),

- modification of the adhesion of cancer cells that can limit metastasis,

- direct action on the abnormal cells causing their destruction (apoptosis),

- activation of a nonspecific immune reaction which can help limit tumor development .

- Some researchers believe that they are potentially useful molecules against certain viruses and pathogenic bacteria including in the digestive system (stomach and intestine) .

The singularity of these fucans is the abundant presence of L-fucose, this sugar is an important "marker" for the cells, (example: differentiation of the blood groups) hence the potential role of fucans in the modulation of the inflammatory or immune reactions (antibiotic power, natural strengthening of the body's defenses) .


Alginic acid and alginates are present in fucus but in less quantity than in laminaria, ascophyllum are a more interesting source:

- Alginic acid is a natural non-assimilable polymer consisting of two units of simple sugar (acid D-mannuronic and L-guluronic acid) of which only the salts (alginates) are soluble in water and form viscous colloidal solutions (gels),

- alginic acid on the other hand can trap the water, absorb it (100 to 200 times its weight),

- Calcium alginate is haemostatic, whereas some alginate sulphates are anticoagula


They are contained inside the cells of fucus and ascophyllum, they are studied for their anti-inflammatory, antibacterial and antifungal power.e.




Fucus is mainly used as an adjunct in DIETING (effect of iodine + effect of fucans), especially when OBESITY is accompanied by hypothyroidism (obese, pale and chilly) and in case of obstinate CONSTIPATION in association with other purgative substances.

Phytomedicines based on fucus thallus powder (containing 20 to 120 micrograms of iodine per gram) or alcoholic fucus extract (110 micrograms of iodine per 10 ml) are available.

(It is recommended not to exceed 120 micrograms of iodine per day).

Examples of DOSAGE:

Phytomedicines based on fucus THALLUS POWDER:
An average dose would be 0.5 to 1 g of thallus powder per day.

ALCOHOLIC TINCTURE of the whole plant (Fucus):
50 to 150 drops of mother tincture a day

When you prepare you own phytomedicine based on dried fucus beware of its origin, it must come from non-industrialized areas and away from a nuclear reprocessing center or nuclear power station. .
It is recommended not to tear the clump of algae but to cut it to several tens of cm of its implantation disk.
Clean the seaweed with clean sea water and dry it, do not macerate it in fresh water to avoid the loss of iodized compounds.

3 to 4 g per day of dried seaweed reduced in powder or fractionated or finely chopped after rehydration
50 to 150 drops of alcoholic dye at 1/10 (easier to use) to take rather in the first part of the day


It is common in Asia to consume algae extracts to stay healthy or boost immunity.

One can find for example "Power fucoidan" which is the result of an enzymatic digestion of the fucans of Cladosiphon novae-caledoniae (it is not a fucus but it is another brown seaweed).

To my knowledge there is no similar product on the European market, yet recent studies have shown that fucans of fucus and other brown algae nearby were pharmacologically more active than this extract marketed in Asia.

Fucans and phlorotannins have no use in Western medicine despite their very interesting pharmacological potential.


It is widely used in the food industry as gelling-stabilizer and in the pharmaceutical industry as encapsulant.

They are also used in the formulation of gastric dressing (protection of the digestive mucosa) and skin dressing especially in the case of oozing ulcers and pressure ulcers.

Calcium alginate wick is the classic remedy for nosebleed.



Iodine-131 is a volatile radio nuclide that is produced rapidly and in large quantities when a chain reaction races in a reactor, and this gas is released into the atmosphere.

Iodine 131 is rapidly absorbed by the body through respiration and attaches mainly to the tissues of the thyroid with the secondary risk of cancer.

This intoxication is prevented by saturating the iodine fixation sites in the thyroid by preventive absorption of potassium iodide (this is not without danger and must be medically motivated).

In the event of a nuclear accident (a fortiori nuclear explosion), it is imperative to follow the indications of the health authorities especially to protect the children.

But in case of isolation or the complete impossibility of obtaining iodide of potassium or other source of iodine, one can try to absorb clean and crushed brown algae in large quantity knowing that they will cause secondary digestive disorders (diarrhea) and that it is an exceptional measure to absorb iodine in an extreme case.

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The rock-weed of the cold seas contain mucilaginous substances which are not digestible, cut the hunger and make it possible to fight constipation.
iodine and minerals of seawater are concentrated by fucus and support the metabolism of the body especially the thyroid gland.
All of this helps to facilitate weight loss .
Fucus contains substances with interesting pharmacological potential to fight cancer or to regulate blood coagulatione