5 Benefits of Bladderwrack: Dosage & Safety

Bladderwrack is a seaweed superfood that has many potential health benefits. As such, its usage is growing in popularity. In this article, we’ll take a look at some of the …

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Written by: Jack Cincotta, MS
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Medical Review by: Daniel Powers, MS
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Bladderwrack is a seaweed superfood that has many potential health benefits. As such, its usage is growing in popularity.

In this article, we’ll take a look at some of the active compounds and nutrients in bladderwrack. We’ll also go over bladderwrack’s health benefits, safety profile, and how to incorporate it into your diet.

5 bladderwrack benefits

What is Bladderwrack?

Bladderwrack, scientifically named Fucus vesiculosus, is a widespread type of brown seaweed found in many coastal regions. It grows throughout the western Baltic Sea, North Sea coastline, and the coastlines of the Atlantic and Pacific oceans.

Its intriguing name comes from the air pockets in its leaves, which resemble little bladders and are evenly distributed throughout the plant. 

Like other seaweeds, bladderwrack is rich in numerous nutrients, including polysaccharides, phenolics, fiber, terpenes, amino acids, proteins, and lipids.

Additionally, bladderwrack contains high amounts of many vitamins and minerals, including calcium, iodine, magnesium, potassium, zinc, vitamin A, and vitamin C.

It is also known for its high concentration of phytochemicals, which are thought to deliver many health benefits. Some of the main phytochemicals in bladderwrack include:

  • Fucoidan
  • Alginic Acid
  • Laminarin
  • Fucoxanthin
  • Phlorotannin

Health Benefits of Bladderwrack:

As mentioned, bladderwrack is a nutritionally-loaded seaweed, so it comes as no surprise that there are many potential health benefits of bladderwrack. Specifically, bladderwrack and its various compounds may help to deliver the following benefits to human health.

5 benefits of bladderwrack

1. May Help with Weight Loss

In this day and age, weight loss is a common goal, as many individuals struggle with being overweight. But fortunately, bladderwrack may have weight loss benefits and may help prevent or reduce obesity. 

For example, in an animal study, rats who were given bladderwrack showed significantly lower weight gain compared to the control group. Moreover, the bladderwrack-fed rats also had better markers of liver and blood lipid health. 

Another study in rats found that, even after giving them a high-calorie, high-fat diet, supplementing with bladderwrack prevented increases in body weight while also keeping triglyceride and cholesterol levels in normal ranges. 

Importantly, the effects of bladderwrack on obesity have also been studied in humans. For example, in one study, overweight or obese subjects were given a supplement called Gdue, which is a combination of bladderwrack and rockweed (Ascophyllum nodosum). After 6 months, they found that supplementation led to significant reductions in waist circumference as well as other markers of metabolic syndrome, including insulin sensitivity. 

Another clinical study was done on over 500 patients with metabolic syndrome. They found that supplementation with Gdue over 6 months led to an average weight loss of 7kg (around 15lbs), and a reduction in waist circumference on average of 7.5cm (about 3 in). 


Combination-treatment studies show that bladderwrack may be a useful herb for promoting weight loss. Human clinical studies are needed for confirmation.

2. May Have Anti-Cancer Effects

Another potential benefit of bladderwrack is its anti-cancer effects for many different types of cancer. This is thought to be due to bladderwrack’s fucoidan content.

In one study involving human ovarian cancer cells, fucoidan extract from Fucus vesiculosus increased the death of various ovarian cancer cells. This was achieved via a decrease in cell proliferation, reductions in reactive oxygen species, and decreased dysfunction in healthy cells. 

An ex vivo study using human peripheral blood mononuclear cells (PBMCs) was done to determine the effects of fucoidan compounds on prostate cancer cells alone and in combination with an immune checkpoint-inhibitor drug called Nivolumab. The fucoidan compounds were able to activate PBMCs and thus reduce prostate cancer cells and engage in cancer cell-killing activity.

Additionally, an in vivo study found that fucoidan was able to inhibit new blood vessel formation and disrupt other structures in breast cancer cells, while also reducing breast tumor growth and overall size. 

A further study in gastric and colorectal cells found that phlorotannin-rich extracts from bladderwrack were able to exert cytotoxic effects on tumor cells without compromising the health of normal cells. The researchers found that phlorotannins were able to decrease cancer cells via apoptosis and necrosis. 

There have also been a few clinical studies done on fucoidan and cancer, including one study that evaluated fucoidan as a supplemental therapy in 54 colorectal cancer patients. It was found that fucoidan supplementation alongside chemotherapy led to a greater disease control rate compared to chemotherapy alone, although some other factors weren’t improved significantly. 


Lab-based research is promising in regards to the potential benefits of bladderwrack for cancer. Human clinical trials are needed to verify.

3. May Support Blood Sugar Regulation

The benefits of bladderwrack also carry over into metabolic health, including blood sugar regulation and diabetes. This is primarily due to its fiber content and various anti-inflammatory compounds.

In a double-blind, randomized, placebo-controlled study, a polyphenol-rich extract from bladderwrack was shown to significantly reduce peak glucose in response to carbohydrate consumption. This has important implications for blood sugar management.

In one study, researchers looked into the effects of bladderwrack and rockweed in mice with a type of liver disease that often precedes type 2 diabetes. They found that both of these seaweeds were able to delay and reduce peak blood glucose while also controlling carbohydrate digestion and absorption. 

Another clinical trial looked at the effects of Fucus vesiculosus, Ascophyllum nodosum, and chromium picolinate on glycemic status in individuals with elevated blood sugar. They found that the group receiving treatment showed reduced HbA1c, decreased glucose, and reduced insulin resistance compared to placebo after 3 months. And after 6 months, more patients tended towards normal glycemic levels in the treatment compared to the control group. 

Additionally, in a randomized crossover placebo-controlled trial involving bladderwrack and rockweed, the treatment group showed improvements in insulin sensitivity after carbohydrate ingestion compared to the placebo. However, there were no significant improvements in glucose responses.


Human clinical trials indicate that bladderwrack may help to stabilize blood sugar.

4. May Support Heart Health

Some of the bladderwrack benefits mentioned so far have an impact on heart health, such as weight reduction and improved insulin sensitivity, but there are also some more specific benefits that show bladderwrack’s ability to benefit heart health

For example, initial in vitro research into the compound fucoidan showed that it had strong anticoagulant and fibrinolytic properties, thus showing promise for preventing blood clots and protecting the heart. 

One of the first studies to evaluate the in vivo and in vitro effects of fucoidan found that it also had strong anticoagulant properties, but these appeared more pronounced in the in vitro analysis.

Another study analyzed six different seaweeds for their anticoagulant properties, with bladderwrack being one of the most effective varieties for its anticoagulant activities. 

In another study in patients with high triglycerides, supplementation with bladderwrack led to significant reductions in blood triglycerides. After 4 months, all patients’ triglyceride levels were reduced to the normal range. Additionally, for two patients that also had elevated LDL and cholesterol levels, these returned to normal after 4 months. 

Lastly, a study with 505 patients found that supplementation with Gdue (a bladderwrack and rockweed combination) resulted in reductions in blood pressure, LDL cholesterol, and triglycerides, whereas HDL cholesterol was increased. The researchers also noted that Gdue supplementation led to an estimated 27% relative risk reduction for cardiovascular events.


Clinical research indicates that bladderwrack supports heart health.

5. May Improve Gut Health

Lastly, it appears that bladderwrack benefits gut health.

For example, some studies have shown that alginate, a compound found in bladderwrack, is able to reduce symptoms of gastroesophageal reflux disease (GERD), heartburn, and related symptoms. This is due to its ability to control and inhibit acid levels. 

Additionally, one study found that phlorotannin extracts from bladderwrack are able to stimulate the growth of beneficial gut bacteria, while also enhancing levels of butyrate and other short-chain fatty acids. In turn, this improves gut microbiome composition and overall gut health. 

Lastly, Fucus vesiculosus may benefit gut health due to its fucoidan content, which is a soluble fiber. Fucoidan extracts have been shown to act as prebiotics and enhance gut health by increasing the number of good bacteria in the gastrointestinal tract.


Small-scale lab studies indicate that bladderwrack may help to support gut health. Human clinical trials are needed to verify these findings.
health benefits of bladderwrack

How to Add Bladderwrack to Your Diet:

There are a number of ways to add bladderwrack to the diet. It can be eaten in its whole form, either raw or cooked. However, it doesn’t have a great taste, so it is often consumed in dried and ground form, typically in powders or capsules that can be taken as supplements. 

Beyond this, one can make bladderwrack tea using the dried form. 

There isn’t any specific recommended dosage for bladderwrack. It is always wise to consult one’s doctor or another healthcare practitioner before implementing any supplement, including bladderwrack.

Bladderwrack Safety:

There is the possibility of an allergic reaction to bladderwrack, so one should be careful to note any symptoms after consuming it. 

Also, due to its high iodine content, individuals with hyperthyroidism should be cautious, as well as anybody who already consumes adequate iodine. 

Lastly, bladderwrack may lead to nausea, bloating, upset stomach, and other digestive symptoms in some individuals.

Overall, though, it is generally safe for most people to consume.

Naming & Taxonomy:

Bladderwrack’s scientific (Latin) name is Fucus vesiculosus

It belongs to the fucacea family (aka the rockweeds), which consists of 6 different brown algae. 

Bladderwrack is easily recognized by its paired bladder-like air pockets on both sides of the frond midrib, with a brownish color.

History & Traditional Use:

Bladderwrack has been used for centuries in traditional and folk medicine. It goes as far back as the Ancient Romans and Greeks, who used it for gout, inflammation, joint pain, and even tuberculosis.

In the 1800s, it became popular due to its high iodine content, which made it useful for treating goiters, other thyroid-related conditions, and obesity, stemming into the 1850s, 1860s, and beyond. 


Bladderwrack is a uniquely-named alga that has been used for centuries for its health benefits. Given its high nutrient density, it’s unsurprising to see the unfolding of many researched benefits of bladderwrack and its compounds. 

In particular, bladderwrack may be useful for weight loss and preventing obesity, offering anti-cancer effects, regulating blood sugar, and aiding type 2 diabetes, while also improving heart health and gut function.

Furthermore, with many different ways to consume this seaweed, there are many opportunities for people to incorporate it into their diet and possibly experience health benefits.

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About Jack Cincotta, MS

Jack has a Master of Science degree in Psychology and is also an AADP® Board Certified Holistic Health Practitioner and AFPA® Certified Holistic Health Coach. His passion is to help people develop optimal levels of health, particularly mental health.

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