The Benefits of Brown Seaweed

Health Benefits, Uses, Side Effects & More

bladderwrack (fucus vesiculosus)
Bladderwrack (fucus vesiculosus) is a type of brown seaweed.. Christina Bollen/Oxford Scientific/Getty Images

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.


Supplements haven't been tested for safety and due to the fact that dietary supplements are largely unregulated, the content of some products may differ from what is specified on the product label. 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.

Also keep in mind that the safety of supplements in pregnant women, nursing mothers, children, and those with medical conditions or who are taking medications has not been established.

You can get tips on using supplements here, but if you're considering the use of brown seaweed, talk with your primary care provider first. 

Using 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 a lack of 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.


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.

Disclaimer: The information contained on this site is intended for educational purposes only and is not a substitute for advice, diagnosis or treatment by a licensed physician. It is not meant to cover all possible precautions, drug interactions, circumstances or adverse effects. You should seek prompt medical care for any health issues and consult your doctor before using alternative medicine or making a change to your regimen.

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