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7 Powerful Health Benefits of Bladderwrack Seaweed

author avatar Dr. Eric Berg 08/31/2023

Bladderwrack is a brown seaweed that’s been used for centuries as a natural remedy for thyroid disorders and to promote overall health and well-being. 


Like most seaweeds, bladderwrack is highly nutritious and an incredibly rich source of iodine; unsurprisingly, bladderwrack supplements are becoming increasingly popular.

Let's look at the many health benefits of bladderwrack!

Bladderwrack seaweed

What is bladderwrack?

Bladderwrack, also known as rockweed, is a type of seaweed commonly found in the intertidal zones of rocky ocean shores.

Like other seaweeds, bladderwrack is edible and remains a popular food source for many Asian coastal communities. It's typically consumed in dried or powdered form and often used as a seasoning added to various dishes.

Bladderwrack seaweed has been used for centuries in traditional medicine, particularly as an herbal remedy for thyroid issues, including goiter and hypothyroidism.

Because bladderwrack benefits health, it's readily available as an herbal supplement in various forms, such as capsules, tablets, tinctures, and dried powder.

Dried bladderwrack

Bladderwrack health benefits

Bladderwrack ranks amongst the most nutritious seaweeds. It’s a rich source of iodine and dietary fiber and contains several bioactive compounds, including fucoidan, phlorotannin, and fucoxanthin.

Research suggests that these health-promoting phytochemicals have potent anticancer, antioxidant, anti-inflammatory, and anti-obesity properties, explaining why bladderwrack has such impressive benefits for your health.

Here are seven health benefits of bladderwrack.

1. Support thyroid health

Bladderwrack seaweed may benefit people with thyroid issues, especially those at risk of iodine deficiency. Without adequate iodine, the thyroid gland can’t produce hormones, resulting in underactive thyroid function, also called hypothyroidism.

Bladderwrack contains significant amounts of iodine, and studies suggest that taking bladderwrack supplements may help improve thyroid function in people with hypothyroidism and goiter, an enlarged thyroid gland that develops as a result of iodine deficiency.

2. Weight loss

Adding bladderwrack extract to your health regimen may help with weight loss. Iodine has potential fat-burning effects by promoting metabolic health. 

A lack of iodine decreases your basal metabolic rate and promotes fat storage, which can lead to weight gain and difficulty losing weight. 

3. Promotes skin health 

Bladderwrack may help delay premature skin aging and improves skin appearance, particularly in people with eczema or psoriasis. 

Evidence confirms that fucoidan, a structural component of bladderwrack, has potent anti-inflammatory properties and stimulates collagen production, promoting skin elasticity and hydration.

Woman suffering from acid reflux

4. May help with GERD

Gastroesophageal reflux disease (GERD) is characterized by stomach acid backing up into the esophagus, causing heartburn and difficulty swallowing. 

Alginic acid, a polysaccharide in bladderwrack, can soothe symptoms of GERD and has been linked to a significant decrease in the flow of stomach acid into the esophagus. 

5. Natural diuretic 

Bladderwrack is a mild diuretic that stimulates the production of urine.

Increased urine output helps flush out excessive fluids, which promotes healthy blood pressure and prevents decreased water retention and bloating.

6. Supports digestive health 

Dietary bladderwrack has been used to relieve constipation for centuries.

It’s high in dietary fiber and contains alginic acid, which promotes gastrointestinal health and stimulates regular bowel movements.

Consuming bladderwrack also supports the beneficial bacteria in your gut and promotes a diverse microflora. This may explain why bladderwrack appears to improve gastrointestinal symptoms in people with irritable bowel syndrome (IBS).

7. May help to reduce inflammation  

Bladderwrack has long been used as a traditional remedy for various inflammatory conditions, including rheumatoid arthritis, eczema, asthma, and endometriosis.

Bladderwrack is a particularly rich source of fucoidan, phlorotannin, and fucoxanthin. This group of phytochemicals has potent anti-inflammatory and antioxidant properties that inhibit the release of inflammatory compounds and protect your cells from oxidation linked to cellular damage and inflammation.

Bladderwrack on shore

Possible side effects of bladderwrack

Eating moderate amounts of bladderwrack is generally considered safe. However, overeating bladderwrack or taking large doses of bladderwrack supplements can have side effects.

Here are some of the health risks of bladderwrack: 

Drug interactions 

It's best to discuss bladderwrack use with your doctor if you are taking thyroid medication or blood thinners

The high amounts of iodine in bladderwrack can interact with thyroid stimulating hormone (TSH), which can worsen thyroid problems and lead to thyroid dysfunction, including hyperthyroidism.  

Some compounds in bladderwrack can slow down blood clotting, which increases the risk of bruising and bleeding, particularly in people who take blood thinning medication. 

Allergic reactions 

People with iodine allergy shouldn't eat iodine-rich seaweed or take seaweed supplements, including bladderwrack products. 

Heavy metal contamination

Like many other seaweeds, bladderwrack can accumulate heavy metals from the water it grows in. Heavy metals, including cadmium and mercury, can harm your health, and it's important to choose bladderwrack grown and harvested in a controlled environment that limits heavy metal exposure. 

Cup of Bladderwrack tea

How much bladderwrack can you take each day?

As a food source, bladderwrack is generally safe in moderate amounts. 

If you want to take a bladderwrack supplement, the recommended dosage may vary depending on the supplement's intended use and exact formulation. A typical recommended dosage of bladderwrack ranges between 100 to 500 milligrams per day. 

Bladderwrack tea has become a popular alternative to supplements. Bladderwrack tea is made by steeping dried or fresh bladderwrack in hot water. To avoid excessive intake of iodine, it's best to consume no more than two cups of bladderwrack tea daily. 

herbal medicine in pestle and mortar

Key takeaways

Bladderwrack is an edible seaweed that can support thyroid health, promotes digestive health, and is used in skincare products.

Because of bladderwrack’s exceptional nutritional value, bladderwrack supplements have become incredibly popular and are available in various forms, such as tablets, capsules, and dried powder. 

There are many bladderwrack health benefits and it’s generally considered safe, however it’s high in iodine, and bladderwrack supplements aren’t recommended for people with iodine allergies and those taking thyroid hormone medications.  


1. What is bladderwrack?

Bladderwrack is a type of edible brown seaweed that belongs to the kelp family. It grows on rocky ocean shores and has been used as a food source and a natural remedy for thyroid disorders for centuries. 

2. What are the health benefits of bladderwrack?

Bladderwrack seaweed is highly nutritious. It's a rich source of iodine and dietary fiber and contains several health-promoting phytochemicals, including fucoidan, phlorotannin, and fucoxanthin. 

Bladderwrack's impressive nutrient content is believed to support healthy thyroid function, promote digestive health, aid weight loss, and is linked to a reduced risk of heart disease.


3. What are the side effects of bladderwrack?

Bladderwrack is generally safe. However, the high amounts of iodine in bladderwrack can interact with thyroid medications, increasing the risk of thyroid dysfunction. In addition, individuals with an iodine allergy should avoid bladderwrack and all other seaweed.

Bladderwrack can also contain heavy metals, including lead and cadmium, which can lead to nerve or kidney damage. It's important to choose bladderwrack products harvested in controlled environments free of heavy metal contaminants.


4. Is bladderwrack good for your heart?

Yes, bladderwrack promotes heart health. It’s rich in polyphenols with potent anti-inflammatory and antioxidant properties that support healthy blood vessels and cardiovascular function.

Research found that consuming seaweed, including bladderwrack, is associated with a 12% lower risk of developing heart disease.

5. Does bladderwrack help with immune system function?

Bladderwrack has immune-boosting properties due to its high content of antioxidants and minerals such as iodine, iron, and zinc. These nutrients are essential for immune cell function and support a robust immune system.

6. How much iodine is in bladderwrack?

The amounts of iodine in bladderwrack can vary depending on the location and growing conditions of the seaweed. However, on average, bladderwrack contains around 600 milligrams per gram of dried seaweed.

7. Is bladderwrack a form of seaweed?

Yes, bladderwrack, also known as rockweed, is a type of edible seaweed that belongs to the kelp family.

8. Can I take bladderwrack while fasting?

Yes, taking a bladderwrack supplement won’t break your fast.

However, some people experience nausea when taking bladderwrack on an empty stomach. Combining bladderwrack supplements with a meal most likely fixes this issue.

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