Seaweeds: A Gift from the Sea

by Peter D'Adamo & Gregory Kelly


The recorded use of Fucus vesiculosus, also called "bladderwrack" or "sea wrack" dates back to at least the time period of the Eclectic Physicians of the 19th century. Historically these physicians used this seaweed for goiter (swelling of the tissue or cells of the thyroid) and for obesity. Published commentary by a turn of the century physician (Dr. J. Herbert Knapp) indicated that he had found this plant to be a specific remedy for both exophthalmic and uncomplicated goiter. In his experience bladderwrack worked best in individuals under age 30, a population for which he claimed a 100% success rate, and was less dependable for normalizing thyroid function in people beyond this age.


Fucus vesiculosus contains a wide spectrum of polysaccharides including fucoidans and fucans. In general, fucoidans are a family of high molecular weight sulfated polysaccharides, widely dispersed in the cell walls of brown seaweed. The core region (or backbone) of fucoidan is composed primarily of a repeating chain of fucose sugars. Fucose is also attached to this backbone, forming branch points at every 2-3 fucose residues within the chain. So, as you can readily deduce, bladderwrack is a rich food source of fucose.

Similar to most plants grown in the ocean, this plant is also very high in iodine and other trace minerals. While iodine is critical for proper health, like most other trace minerals, too much good can be no good. In other words more is not always better. So bladderwrack in an appropriate dose is safe to take long-term; however, you would not want to consume ridiculously large amounts of this plant for indefinate periods of time (even if you are an O).

Fucus vesiculosus and Blood Type O: Metabolic and Anti-adhesion Food

In ER4YT, Dr. D'Adamo mentions Fucus vesiculosus as being particularly beneficial for blood type O's. He states, in reference to blood type O individuals, that "bladderwrack seems to help normalize the sluggish metabolic rate and produce weight loss." He also alludes to its utility in helping to keep thyroid function normal in blood type O's, and discusses the potential usefulness of this plant for preventing the adherence of some unwanted microorganisms (H. pylori in his book's example) to the cells lining the digestive tract in blood type O's.

There is actually a good reason for his deference to this plant with regards to blood type O. As you might recall form ER4YT, blood type O is characterized by the presence of a terminal fucose sugar on its antigen. Things in nature (like lectins, bacteria, Candida, etc) with a preference for or a "sweet tooth" for fucose, will always have an affinity for and a greater impact on blood type O's. Since bladderwrack is such excellent food source of fucose and fucose containing sugar chains, it can actually bind many of the more problematic blood type O lectins, bacteria, and microorganisms.

One of the emerging fields of research with regards to microorganisms (and lectins) centers about an idea of adherence and anti-adherence. Basically, an unwanted organism can only produce a problem for you to the degree it can attach to or anchor itself to your cells. Lectin damage follows a similar pattern. Recognizing this simple concept of adhesion, you will readily recognize the usefulness of the concept of anti-adhesion, or blocking strategies. The question then becomes what foods might provide an anti-adhesion advantage for your blood type. One of the answers for blood type O is bladderwrack (Note: kelp also has a high amount of fucose sugars so is another answer). Basically, the fucose in bladderwrack can act as a false decoy, binding the unwanted blood type O environmental debris and sweeping it away before it can bind to or irritate the tissue.

Because A's, B's and AB's also usually contain some anchoring sites (but proportionately substantially less than an O) for fucose specific lectins and microorganisms, bladderwrack can also act as a form of anti-adhesion food for these blood types as well. However, they also have additional specific blocking sugars they can place at their disposal.

Fucus vesiculosus: Anti-microbial Activity

The fucoidan found in bladderwrack inhibits the growth of many unfriendly bacteria and viruses. Some of the viruses this compound is antagonistic to include herpes simplex virus, human cytomegalovirus, and human immunodeficiency virus. Bladderwrack has been found to agglutinate the cells of several strains of Candida. Bladderwrack also has a toxic effect on some strains of E. coli and all strains tested of Neisseria meningitidis.

Let's look at a few specific examples of bladderwrack research in the microbial world. The complex sugar structures and other compounds found in bladderwrack have anti-HIV activity. Some of the mechanisms of its activity fall back into the world of our new friend "anti-adhesion". Researchers have suggested that, since adhesion is the initial step in HIV infection, blocking adhesion might prevent HIV-1 transmission. In vitro evidence supports this suggestion with the complex fucose structures found in bladderwrack showing a capability to block HIV adhesion to cells. These same blocking strategies with fucose sugars have also been used in studies of malaria to prevent its spread to additional red blood cells. In essence these sugars inhibit invasion of your red blood cells by the malaria parasite. Dr. D'Adamo has written that Fucus vesiculosus is a specific for blocking attachment of H. pylori---an organism responsible for inducing ulcers and gastritis---in individuals with blood group O.

While no one is suggesting that bladderwrack should be thought of as a solution for HIV or other infectious diseases, one might ponder the question of how the shape of medicine might change if we could use blood type strategies to block HIV and other microorganism from attaching to your cells in the first place. Or, ponder the question of how could we employ blood type anti-adhesion strategies in support of conventional use of antibacerial and anti-microbial drugs. If you are a blood type O, the preliminary answer to these questions begins with pondering what health benefits might accrue with the consumption of this common edible seaweed.

Fucus vesiculosus: Immunomodulating Activity and Anti-inflammatory Activity

The fucose sugars in bladderwrack can beneficially impact immune system health by stimulating immunoreactions of the humoral and cellular types, and by enhancing the phagocytosis (or consumption of invaders) by your macrophages. These same complex fucose sugars also offer several advantages that counter the blood type O tendency to inflammation. Essentially they block the recruitment or inhibit an overly aggressive inflammatory immune response at sites of inflammation.

Fucus vesiculosus: Normalizing Metabolism and Thyroid Function

The historical uses of Fucus vesiculosus were primarily as an agent to enhance thyroid function in cases of goiter and as an aid in weight loss for obesity. This remains the primary use of this plant today in natural medicine.

Typically, the credit for its activity in thyroid conditions has been given to its high content of iodine; however, the high fucose content of this plant, because of its immune and inflammatory balancing effects, appears to be responsible for some of the observed benefits on optimizing thyroid function in blood type O's.

If you are a blood type O and plan on consuming bladderwrack as an aid to metabolism and thyroid health, this plant generally works very slowly. A minimum of 3 months is probably warranted, but in many instances best results are produced when bladderwrack is consumed regularly at a low dose for about 1 year.


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Reviewed and revised on: 01/12/2023      
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Many sea vegetables, and in particular bladderwrack, have many unique characteristics and properties and are used extensively as food in coastal cuisines around the world.

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