Bladderwrack: Health Benefits, How To Use, And Side Effects

This particular seaweed may just be the answer to multiple health issues.

Medically reviewed by Olga AfonskyOlga Afonsky, MS, LDN
By Aparna MallampalliAparna Mallampalli, BEd (Biological Sciences), MSc (Microbiology), Diploma In Nutrition  • 

Bladderwrack is popular for its medicinal properties. It is commonly used in traditional medicine as a supplement. The health benefits of bladderwrack are evident with its impressive nutritional profile. This seaweed is known to help manage several health conditions. But what does science say? Does bladderwrack have any side effects? Continue reading to understand.

protip_icon Know Your Ingredient: Bladderwrack

What Is It?
A nutrition-rich, olive-brown shoreline seaweed.

What Are Its Benefits?
It may help manage thyroid disorders and diabetes, improve gastrointestinal function, and reduce the risk of ischemic stroke.

Who Can Consume It?
Anyone with digestive issues, increased glucose levels, and hypertension may consume bladderwrack.

How Often?
You can consume it regularly.

Avoid overconsumption as it may aggravate acne and lead to digestive problems like nausea, vomiting, diarrhea, and bloating.

What Is Bladderwrack?


Image: Shutterstock

Bladderwrack is a seaweed that grows on the coasts of the North Sea, Western Baltic Sea, and the Atlantic and Pacific Oceans. It is commonly known as black tang or brown seaweed. Many consume bladderwrack for its medicinal properties. It is especially used for managing thyroid disorders as it contains iodine, an essential component for maintaining normal thyroid function (1).

protip_icon Trivia
French chemist Bernard Courtois first extracted iodine from bladderwrack in 1811.

Continue reading to know about the nutritional value of bladderwrack.

Bladderwrack Nutrition Profile

A hundred grams of dried bladderwrack powder contains (2):

Protein12.99 g
Lipid3.75 g
Ash20.71 g
Calcium1160.27 ± 23.10 mg
Iron18.99 ± 0.32 mg
Potassium3745.05 ± 36.01 mg
Manganese8.28 ± 1.07 mg
Sodium2187.51 ± 36.90 mg
Amino Acids11.90 g
Magnesium1.96 mg – 8.28 mg

Bladderwrack is chock-full of nutrients and has multiple health benefits. Let’s understand how it can keep you healthy.

Bladderwrack Health Benefits

 Bladderwrack improves gastrointestinal function

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1. Improves Gastrointestinal Function

Bladderwrack contains high levels of dietary fiber, which promotes gastrointestinal health. Dietary fiber helps regulate the intestinal flow and also stimulates the growth of gut-friendly microbiota.

2. Helps Manage Diabetes


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Bladderwrack contains fucoidans, bioactive compounds with potent anti-diabetic properties. They can reduce glucose absorption into the bloodstream, increase serum insulin levels, and help manage diabetes. Animal studies found that oral intake of bladderwrack reduced fasting blood glucose levels.

3. Has Anticoagulant Properties

The fucoidans in bladderwrack make it an excellent anticoagulanti  XA substance (also called blood thinners) that prevents blood clot formation by slowing down blood’s ability to clot. . Animal studies found that fucoidans could mimic the action of heparin, a potent anticoagulant. This may reduce the risk of ischemic strokei  XA common type of stroke that occurs when blood clots in the artery block blood flow to the brain. by minimizing blood clotting tendency in people with a history of hypertension and diabetes. However, the exact mechanism of how it works is not yet clear and needs further research.

protip_icon Trivia
Bladderwrack has been in use since the early 1300s when King Denis of Portugal regulated the harvest of this seaweed.

4. Has Antitumor Properties

Fucoidans have antitumor properties and were found to significantly inhibit the number of metastasesi  XRefer to the spread of cancer cells from the primary location to different body parts through the blood or lymph system. in lung carcinoma (in mice studies) and exhibit anticancer activities (3).

5. Antiviral Properties

The fucoidans in bladderwrack have a capacity to inhibit poliovirus III, adenovirus III, ECHO6 virus, herpes simplex virus (HSV), cytomegalovirus (CMV), and dengue virus (3). However, the exact mechanism remains unclear.

If you are wondering how to include bladderwrack in your diet, read the next section.

How To Take Bladderwrack And Recommended Dosage

Bladderwrack supplements

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Seaweeds, in general, have a fishy smell, which can be unpleasant for a few when consumed as they are or in powdered form. That is why bladderwrack and other seaweed supplements are available in capsules.

It is best to consult a doctor to determine the ideal dosage (usually, it does not exceed three capsules), depending on your health condition and nutritional requirements, as unregulated intake may cause side effects.

Side Effects Of Bladderwrack

Nausea is a side effect of bladderwrack

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Bladderwrack is possibly safe when taken in small amounts. But anecdotal evidence suggests that excess intake may cause a few side effects like:

  • Nausea And Vomiting: Its unpleasant taste and odor may make you nauseous and cause vomiting.
  • Diarrhea: A few people reported experiencing diarrhea and sticky stools after taking bladderwrack supplements. This might be due to bladderwrack’s nutrient-dense nature. You may also experience dehydration due to diarrhea. Hence, consume adequate amounts of fluids to combat this.
  • Bloating: Excess consumption of bladderwrack may cause bloating and gastric pain, which may be due to the high fiber content. Stay hydrated to minimize this side effect.
  • Tingling Sensation In The Throat: If you are allergic to bladderwrack, it may cause itching and tingling sensation in the throat.
  • May Aggravate Acne: Excess consumption of bladderwrack may worsen acne due to its high iodine content. However, there is no research to prove the exact mechanism.

If you experience any of the symptoms, stop consuming bladderwrack supplements. If the effects persist for over three days, consult a doctor immediately.

Bladderwrack’s benefits can be attributed to its nutritional content. When included as a part of your regular diet, bladderwrack can promote gastrointestinal function, help in managing diabetes, and exhibit anti-coagulant properties. It also has anti-tumor and anti-viral properties. Bladderwrack is generally taken in the form of capsules. Although it is generally considered safe, it can trigger nausea, vomiting, diarrhea, bloating, a tingling sensation in the throat, and aggravate acne if taken in excess amounts. Hence, caution is advised when consuming it. However, you can take bladderwrack or its supplements with medical advice to promote your overall health.

Frequently Asked Questions

Is bladderwrack good for the liver?

Yes. The extracts of bladderwrack help improve glycemic control and also reduce the risk of non-alcoholic fatty liver disease (4).

Is bladderwrack good for hair growth?

Anecdotal evidence suggests that the presence of a wide variety of nutrients in bladderwrack may help improve hair growth and also combat oxidative stress. However, limited data is available to prove these claims.

Does bladderwrack lower estrogen?

Yes. In one study, the intake of bladderwrack showed a significant decrease in estradiol (primary form of estrogen) levels in a person with high serum estrogen levels (5).

Can I take sea moss and bladderwrack together?

Yes. You can take sea moss and bladderwrack together. They are readily available in capsule or powder forms and can be added to your favorite smoothies or shakes.

How does bladderwrack make you lose weight?

Anecdotal evidence suggests that bladderwrack aids weight loss by stimulating the thyroid gland. However, limited data is available to prove this claim.

Key Takeaways

  • Bladderwrack, also known as brown seaweed, is rich in protein, calcium, iron, and magnesium.
  • Consuming bladderwrack may promote digestion, reduce blood glucose levels, and minimize blood clotting in individuals with high blood pressure and diabetes.
  • However, excess consumption of bladderwrack may result in side effects such as nausea and vomiting.


Articles on StyleCraze are backed by verified information from peer-reviewed and academic research papers, reputed organizations, research institutions, and medical associations to ensure accuracy and relevance. Read our editorial policy to learn more.

  1. Promoting Healthy Thyroid Function with Iodine Bladderwrack Guggul and Iris
  2. Proximate Composition and Nutritional Value of Three Macroalgae: Ascophyllum nodosum Fucus vesiculosus and Bifurcaria bifurcata
  3. Phycochemical Constituents and Biological Activities of Fucus spp.
  4. Fucus vesiculosus and Ascophyllum nodosum Ameliorate Liver Function by Reducing Diet-Induced Steatosis in Rats
  5. The effect of Fucus vesiculosus, an edible brown seaweed, upon menstrual cycle length and hormonal status in three pre-menopausal women: a case report
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