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Brown Seaweed

Health Benefits, Uses, Side Effects & More

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Updated August 02, 2013

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Two types of brown seaweed, Fucus vesiculosus (also known as bladderwrack) and Laminaria japonica, are sometimes used in traditional medicine systems to treat various health conditions. Both seaweeds contain iodine (a trace mineral needed for normal metabolism of cells) and fucoidan (a substance thought to possess immune-stimulating properties).

Uses for Brown Seaweed

Brown seaweed is typically used for the following conditions:

Some proponents claim that brown seaweed can also help promote weight loss, as well as aid in skin care.

Health Benefits of Brown Seaweed

To date, very few scientific studies have looked at brown seaweed's impact on human health. Although there is currently a lack of evidence to support the use of brown seaweed in treatment of any condition, preliminary research suggests that brown seaweed extract may offer these health effects:

1) Cancer Prevention

In a case report published in 2004, researchers found that dietary intake of bladderwrack produced anti-estrogenic effects in three pre-menopausal women. According to the study's authors, these findings suggest that bladderwrack may help reduce risk of estrogen-related cancers. However, the authors caution that further research is needed before any conclusions about bladderwrack's cancer-fighting effects can be drawn.

2) Reduced Inflammation

In a lab study published in 2007, researchers examined the health effects of fucoidan extracted from nine species of brown seaweed. Results revealed that all fucoidans delivered anti-inflammatory effects. What's more, bladderwrack-derived fucoidans appeared to prevent breast cancer cells from adhering to platelets, suggesting that the substances could help inhibit the spread of cancer.

3) Blood-Thinning Benefits

In test-tube research, scientists have found that fucoidan may possess anti-coagulant (blood-thinning) properties. Although these findings indicate that brown seaweed may help prevent blood-clotting, there are no human studies available to support brown seaweed's use as an anticoagulant.

Safety

The National Institutes of Health warn that, due to possible contamination with heavy metals, consumption of bladderwrack "should always be considered potentially unsafe." Furthermore, overconsumption of iodine may disrupt thyroid health, as well as lead to lowered blood sugar, stomach irritation, and/or increased risk of bleeding.

How to Use Brown Seaweed

Some types of brown seaweed can be consumed as a food (in salads, soups, and stir-fries, for instance). Although brown seaweed is also available in supplement form, there is limited scientific evidence to support the use of brown seaweed supplements.

Given the potential health risks associated with brown seaweed consumption, it's important to consult your health-care provider before using brown seaweed supplements or consuming brown seaweed on a regular basis.

Sources

Cumashi A, Ushakova NA, Preobrazhenskaya ME, D'Incecco A, Piccoli A, Totani L, Tinari N, Morozevich GE, Berman AE, Bilan MI, Usov AI, Ustyuzhanina NE, Grachev AA, Sanderson CJ, Kelly M, Rabinovich GA, Iacobelli S, Nifantiev NE; Consorzio Interuniversitario Nazionale per la Bio-Oncologia, Italy. "A comparative study of the anti-inflammatory, anticoagulant, antiangiogenic, and antiadhesive activities of nine different fucoidans from brown seaweeds." Glycobiology. 2007 17(5):541-52. Epub 2007 Feb 12.

Dürig J, Bruhn T, Zurborn KH, Gutensohn K, Bruhn HD, Béress L. "Anticoagulant fucoidan fractions from Fucus vesiculosus induce platelet activation in vitro." Thromb Res. 1997 Mar 15;85(6):479-91.

Memorial Sloan-Kettering Cancer Center. About herbs: Bladder wrack. Updated October 2009.

National Institutes of Health. Seaweed, kelp, bladderwrack: MedlinePlus Supplements. August 2009.

Skibola CF. "The effect of Fucus vesiculosus, an edible brown seaweed, upon menstrual cycle length and hormonal status in three pre-menopausal women: a case report." BMC Complement Altern Med. 2004 4;4:10.

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