Bladderwrack extract

Bladderwrack extract (Seaweed) Fucus vesiculosus iodine alginic acid fucoidan

Parts used and where grown
Bladderwrack is a type of brown algae (seaweed) that grows on the northern Atlantic and Pacific coasts of the United States and on the northern Atlantic coast and Baltic coast of Europe. The main stem of bladderwrack, known as the thallus, is used medicinally. The thallus has tough, air-filled pods or bladders to help the algae float¡ªthus the name bladderwrack. Although bladderwrack is sometimes called kelp, that name is not specific to this species and should be avoided.

Historical or traditional use (may or may not be supported by scientific studies)
Bladderwrack¡¯s mucilaginous thallus has long been used to soothe irritated and inflamed tissues in the body.1 It was also historically used as a bulk-forming laxative.2 People living near oceans or seas have a historically low rate of hypothyroidism, due, in part, to ingestion of iodine-rich food, such as seafood and seaweeds like bladderwrack. It has also been used to counter obesity, possibly due to its reputation for stimulating the thyroid gland. Clinical research in this area has failed to confirm that seaweeds like bladderwrack help with weight loss,3 though more specific research is warranted.

Active constituents
There are three major active constituents in bladderwrack: iodine, alginic acid, and fucoidan.

The amount of iodine in bladderwrack is highly variable,4 probably as a result of different amounts of iodine in the water where it grows. A reasonable portion of bladderwrack may contain the U.S. adult recommended dietary allowance (RDA) of iodine (150 mcg). The RDA amount of iodine is believed to be necessary for maintenance of normal thyroid function in adults (infants and children need proportionally less). Thus, in people with insufficient iodine in their diet, bladderwrack may serve as a supplemental source of iodine. Either hypothyroidism or goiter due to insufficient intake of iodine may possibly improve with bladderwrack supplementation, though human studies have not confirmed this.

Alginic acid is a type of dietary fiber that can be used to help relieve constipation and diarrhea. However, human studies have not been done on how effective bladderwrack is for either of these conditions. An over-the-counter antacid, Gaviscon?, containing magnesium carbonate and sodium alginate (the sodium salt of alginic acid), has been shown to effectively relieve the symptoms of heartburn compared to other antacids in a double-blind study.5 However, bladderwrack has not been studied for use in people with heartburn. Bladderwrack might also help indigestion, though again clinical trials have not been conducted. Calcium alginate (the calcium salt of alginic acid) has shown promise as an agent to speed wound healing in animal studies6 but has not been demonstrated to be effective in humans.

Alginic acid has also been shown to inhibit HIV in the test tube.7 However, this effect has not been studied in humans. Alginic acid may help lower LDL (¡°bad¡±) cholesterol levels, according to animal studies.8 No human trials have studied this effect of bladderwrack. It is widely used in food and pharmaceuticals as a thickener and gelling agent.9