Bladderwrack Benefits, Uses and Side Effects - Dr. Axe

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Bladderwrack Benefits for Thyroid Health, Digestion & Healthy Aging


Bladderwrack - Dr. Axe

As is the case with so many of the Earth’s herbs, bladderwrack has been used in alternative and folk medicine for centuries. Now, this nutrient-dense seaweed in gaining popularity in the natural health space as a nutritional supplement.

Seaweeds are known for their key nutrients and health-promoting compounds, and bladderwrack is no different. In fact, it’s one of the most common seaweeds and has very high nutritional value, especially because of its iodine content.

Just like kelp and sea moss supplements, bladderwrack can be used to reverse nutrient deficiencies and promote overall health.

What Is Bladderwrack?

Bladderwrack is a common seaweed with the scientific name Fucus vesiculosus. Depending on location, it’s known by other names, including red fucus, rockweed, black tang, Atlantic kelp, bladder fucus and cutweed. It’s a type of brown algae that’s characterized by its branches with small air sacs.

Bladderwrack seaweed has a high content in dietary fiber, minerals and vitamins. It’s known for its exceptional combination of macro- and micronutrients, which explains why it’s been harvested and used as food in far East Asian countries and coastal countries of Western Europe.


Today, the seaweed is gaining recognition in the U.S. because of its ability to improve thyroid health and possibly aid weight loss.

Here are a few of the most common types of seaweeds and algae that are used as foods and/or supplements:


The nutritional content of seaweed lends to its many health benefits. Research published in Marine Drugs indicates that bladderwrack has a wealth of bioactive compounds that possess antioxidant, anti-inflammatory, anti-tumor, anti-obesity, anti-coagulant and anti-diabetes properties.

Let’s dive a little deeper into the many bladderwrack benefits:

1. Provides Iodine

Iodine is a vital nutrient for thyroid health and many other body functions. It protects against certain cancers, supports brain function, and is critical for healthy growth and development.

Bladderwrack and other seaweeds are iodine-rich foods, so consuming them is an easy way to maintain healthy levels of this important nutrient.

One of the most well-known benefits of iodine is its ability to support thyroid health. The thyroid needs enough iodine to make important hormones like thyroxine. These hormones regulate critical biochemical reactions in the body, like synthesizing amino acids and allowing for proper nervous system development.

Iodine deficiency can cause thyroid disorders, leading to symptoms like weight and mood fluctuations, sluggish metabolism, and heart complications.

2. Rich in Antioxidants

Bladderwrack contains powerful antioxidants, including beta-carotene, lutein and zeaxanthin.

Beta-carotene is a plant pigment that’s converted to vitamin A in the body. It’s a powerful antioxidant that plays an important role in maintaining healthy vision, boosting skin health and supporting neurological function.

Zeaxanthin and lutein are antioxidants that are also found in leafy greens, like kale. They help maintain healthy vision and eye health by protecting healthy cells and working to prevent retinal damage.

Research indicates that these antioxidants have protective effects against eye disease and are linked to better cognitive performance. The antioxidants found in seaweeds are also used topically to promote healthy aging and boost skin health.

3. Reduces Inflammation

Bladderwrack seaweed contains powerful nutrients that have anti-inflammatory effects, including fucoidans, a class of sulfated polysaccharides. These compounds have been studied for their antioxidant, anticancer, immune-modulatory and anti-inflammatory effects.

Researchers suggest that fucoidan works to alleviate inflammatory conditions by significantly reducing pro-inflammatory cytokines.

Because of its anti-inflammatory properties, the brown algae is also used as an alternative treatment for arthritis, and it’s applied topically to ease insect bites and burns.


4. Aids Digestion

Studies highlight that seaweeds are rich in dietary fiber, which contributes to their health benefits. Brown algae acts as a mucilage when ingested, which means that it creates a gel-like substance that relieves constipation, bloating, cramping and digestive disorders.

Beyond constipation, bladderwrack pills or supplements are also used to cleanse the body or promote detoxification.

Because of its fiber content, bladderwrack may also increase feelings of satiety, making you feel full faster and potentially contributing to weight loss.

5. May Promote Weight Loss

Bladderwrack contains L-fucose compounds that are believed to have anti-obesity effects. One animal study found that L-fucose decreased body weight gain, fat accumulation and triglyceride elevation when fed to mice on a high-fat diet.

Researchers concluded that the compound may be a novel strategy to treat obesity and fatty liver induced by a high-fat diet.

6. Supports Heart Health

There is some evidence that bladderwrack helps support cardiovascular health. One study published in Oxford Academic found that fucoidans in bladderwrack displayed strong antithrombin and anticoagulant activity in platelet tests.

Research also suggests that bladderwrack can increase HDL cholesterol levels. HDL, or high-density lipoprotein, cholesterol is known as the “good cholesterol” because it actually picks up excess cholesterol in the bloodstream and takes it back to the liver, where it can be broken down.

By increasing HDL cholesterol, brown algae can reduce your risk of atherosclerosis and heart disease.

7. May Reduce Risk of Cancer

A case study involving three women found that bladderwrack seaweed may be an important dietary component that’s responsible for the reduced risk of estrogen-related cancers that’s seen in Japanese populations.

Researchers found significant anti-estrogenic and progestagenic effects following kelp administration. They concluded that dietary bladderwrack may prolong the length of the menstrual cycle and exert anti-estrogenic effects in pre-menopausal women.

This, however, was a case report. To fully understand the potential of bladderwrack for breast cancer and other estrogen-related diseases, well-controlled clinical trials are needed.

How to Use

Bladderwrack can be consumed as food, eaten raw or cooked. It doesn’t have the most pleasant flavor, sometimes described as salty fish, so it’s often dried and ground, or it’s consumed as bladderwrack tea.

It’s available as an herbal supplement in powdered and capsule forms. It’s also common to find a combination of sea moss and bladderwrack in capsules or powders.

What is an appropriate dosage? There is no recommended dose for bladderwrack, as it depends on your health status and needs. Before using bladderwrack to improve a thyroid condition or aid weight loss, speak to your healthcare professional about proper dosing and what amount of iodine you need for your situation.

Risks and Side Effects

If you experience stomach pains, stomach cramps, chest tightness, swelling or rash after consuming bladderwrack, discontinue use immediately. These are signs of a bad reaction or allergy.

Some people are allergic to iodine, so consuming bladderwrack can have adverse or even dangerous side effects.

If you have hyperthyroidism, you likely do not need an increase of iodine, so speak to your doctor before consuming the seaweed or using bladderwrack supplements.


There are a number of bladderwrack interactions to be aware of before using it to improve any health issues. Fucus may not be safe to consume in therapeutic doses if you are already on blood thinners, drugs that dissolve blood clots, or drugs like reduce inflammation, like NSAIDs, aspirin and ibuprofen.

People on thyroid medications, like levothyroxine, thyroid desiccated and liotrix, should consult their doctors before using bladderwrack powders or supplements.

Anyone with kidney or thyroid issues shouldn’t use brown algae supplements before discussing it with a health care professional beforehand.


  • Bladderwrack is a common brown algae that’s valued for its iodine, antioxidant and fiber content.
  • This brown algae is used to reverse an iodine deficiency, aid digestion, boost weight loss, promote healthy aging and support heart health.
  • Like all seaweeds, it’s a nutrient-rich food that features a range of powerful antioxidants and compounds.

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