Bladderwrack Supplement Uses, Benefits, Dosages, and Side Effects

Bladderwrack is a species of brown seaweed that has been used as food and medicinally for centuries.

It is a rich source of iodine, which is necessary for the proper function of the thyroid gland. Bladderwrack is purported to support an increased metabolism because of its effects on the thyroid.

This seaweed is also a rich source of fucoxanthin, a carotenoid that is currently being studied for potential fat-burning effects.

Bladderwrack is purported to decrease inflammation, soothe irritated tissues, improve circulation, promote weight loss, maintain bone/joint health and decrease free radical damage. [1, 2]

Bladderwrack supplements are used for gastrointestinal disorders, diabetes, obesity, iodine deficiency, and hypothyroidism (low production of thyroid hormones). [3]

This article will review what bladderwrack is, how it works in the body, purported health benefits, supplement dosages, side effects, and drug interactions.

Bladderwrack

Plant Extract

Thyroid Health

Metabolism

Digestion

How It Works:

• Rich source of iodine
• Supports normal thyroid activity
• Mucilage content supports digestive health

Dosage:

Between 200-600 mg per day

Safety:

Rated Possibly Safe

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Bladderwrack Plant Description

Bladderwrack is a type of large brown seaweed with the scientific name Fucus vesiculosus.

It is a perennial seaweed that grows in northern regions of the Atlantic and Pacific Oceans, and in the Baltic Sea. It is a canopy-forming seaweed with fronds that grow up to 30 feet in length. [3]

The Encyclopedia of Life (EOL) states that bladderwrack develops bladders along the edges of its fronds. These air-filled pockets help the seaweed float and allows it to stand erect in the water. [2]

While classified as a brown seaweed, it can vary in color from brown to olive-green. It is sturdier than species of green seaweed and does not tear apart easily. [2]

This plant grows along water retaining walls, and on wooden poles. It also attaches to stones, mussels or other objects for support in the water. [2]

The Natural Medicines Comprehensive Database (NMCD) reports some other names of bladderwrack include Black Tang, Blasentang, Cutweed, Dyer’s Fucus, Fucus, Ocean Kelp, Rockwrack, Sea Oak, Seawrack, and Varech. [3]

Do not confuse this species with Algin, Bladderwort, Blue-green Algae, Brown Algae, or Laminaria. [3] These are different types of seaweeds and they have different medicinal uses and effects.

How Does Bladderwrack Work Inside the Body?

Herb Wisdom states that bladderwrack is purported to be:

• A demulcent (relieves mucosal inflammation and irritation)
• A gentle metabolic stimulant
• A nutritive (provides nutrition)
• An adaptogen (helps the body adapt to stress)
• An anti-inflammatory (relieves redness and swelling)
• An anti-obesity agent
• An antirheumatic (counteracts rheumatism and rheumatic disease) [5]

Bladderwrack is known to be high in iodine. The University of Michigan Health System (UMHS) reports that people who live near oceans have lower rates of hypothyroidism in general.

This is thought to be due to high iodine levels in some seafood, and in seaweed and other sea vegetables that these people regularly consume. [4]

In addition to iodine, bladderwrack contains selenium, manganese, zinc, phosphorus, calcium, magnesium, potassium, sodium, sulfur, silicon and iron. [5]

It also contains some B-complex vitamins and vitamins A, C, E and K. It is also a source of algin, mannitol, carotene, zeaxanthin, and traces of bromine. [5]

According to Examine, bladderwrack contains L-fructose compounds that are thought to be antiobesity, anti-inflammatory, anticarcinogenic (inhibits cancer development), and antioxidant (resists and repairs free radical damage). It may also work against diabetes and viral infection. [1]

NMCD reports other constituents include phenolics, phlorotannins, mucopolysaccharides, lipids (fats), and various ester diglycerides. [3]

This plant is also known to contain fucoxanthin, which is a carotenoid or plant pigment.

This compound is fat-soluble, which means it can be stored in fat cells. It is being studied for its effects on inducing fat loss and inhibiting fat cell proliferation and differentiation. [6]

Preliminary clinical evidence shows that it may have effects as a non-stimulatory fat loss agent in humans when used over a period of 4 months. More research is needed to confirm its efficacy. [6]

The NMCD reports that the following mechanisms of action have been observed in in vitro (cultured cell) and animal research studies using bladderwrack:

• Antilipemic effects (counteracts accumulation of fatty substances in arteries)
• Antibacterial effects
• Anticancer effects
• Anticoagulant effects (prevents blood clotting)
• Antifungal effects
• Anti-inflammatory effects
• Antiviral effects
• Neuroprotective effects
• Weight loss effects [3]

These effects have been seen in laboratory studies and experimental animals but may not have been observed in humans yet. Clinical human research on bladderwrack’s mechanisms of action is limited.

However, in preliminary clinical trials this supplement has been observed to have antidiabetes, dermatological, hormonal, and weight loss effects. [3]

Uses for Bladderwrack

The UMHS reports that bladderwrack is a mucilaginous plant that has been used for centuries to relieve irritated or inflamed body tissues. It has also been used as a bulk laxative. [4]

EOL states that bladderwrack has also been used in the past to treat joint pain, reduce swelling and redness, and to improve skin diseases. [2]

This supplement is believed to have thyroid-stimulating properties and is used by some people to increase metabolism and counter obesity. However, to date, very little clinical research has been done on weight loss effects. [4]

The NMCD reports that people use this plant extract orally for:

• Anxiety
• Arteriosclerosis (hardening of arteries)
• Chronic fatigue syndrome (CFS)
• Constipation and diarrhea
• Decreasing resistance to disease
• Detoxifying the blood
• Genitourinary (genital and/or urinary) disorders
• Goiter (enlarged thyroid gland)
• Heartburn
• Hypertension (high blood pressure)
• Hypothyroidism (low thyroid activity)
• Iodine deficiency
• Obesity
• Osteoarthritis (joint cartilage degeneration) [3]

Bladderwrack is also applied topically for improving wound healing and preventing skin aging. [3]

Bladderwrack Health Benefits

The UMHS reports that this seaweed is being studied for the following conditions: [3]

• Constipation
• Diarrhea
• Gastritis (inflamed colon lining
• Gastroesophageal reflux disease (GERD)
• Hypothyroidism
• Iodine deficiency
• Low stomach acidity/heartburn
• Wound healing [4]

Published results of clinical trials are limited at this time. Promising results have been seen in trials using this supplement for diabetes, hormonal effects in premenopausal women, skin thickening and aging, and weight loss. [3]

More clinical research is needed to determine the therapeutic efficacy of bladderwrack for these and other conditions.

Bladderwrack extract is regulated as a dietary supplement in the United States and the FDA has not approved it as a drug to prevent or treat any medical conditions.

GERD, Gastritis, and Similar Conditions

Bladderwrack has been used traditionally as a soothing herb for treating heartburn and acid reflux. Some other demulcent herbs also used for this purpose are marshmallow, licorice, slippery elm, and aloe vera. [4]

The UMHS states, “The mucilage content in slippery elm appears to act as a barrier against the damaging effects of acid on the esophagus in people with heartburn.” [4]

Researchers think the alginic acid constituent in bladderwrack may act in a similar way. These effects might be helpful for GERD and heartburn. [4]

This effect could be beneficial for other gastrointestinal disorders. The UMHS states, “Bladderwrack is high in mucilage, which may be advantageous for people with gastritis because its slippery nature soothes irritated mucus membranes of the digestive tract.” [4]

However, this seaweed has not been studied yet for these purposes. Research is needed to determine if it has effects on GERD, heartburn, or similar conditions.

Hypothyroidism

Iodine is an elemental mineral that is required for proper thyroid gland function and to make the hormones Triiodothyronine (T3) and Thyroxine (T4).

T3 has three atoms of iodine in its molecular structure and T4 has four iodine atoms.

Bladderwrack has high iodine content and may raise levels of this essential trace mineral in the body. This may support thyroid function in those who have low thyroid hormone activity due to a dietary deficiency in iodine.

According to UMHS, “Hypothyroidism due to insufficient intake of iodine may possibly improve with bladderwrack supplementation […].” [4]

At this time, clinical studies have not been conducted to determine what effects bladderwrack has on iodine levels and hypothyroidism. Research is needed in this area.

Wound Healing

Bladderwrack may support wound healing as it seems to sooth irritated and inflamed tissues.

This seaweed contains a compound called alginic acid, also known as alginate. The UMHS states, “Calcium alginate has shown promise as an agent to speed wound healing.” [4]

Human research using alginate for wound healing is limited but promising.

Wound dressings containing alginate derived from seaweeds have been used for many years in hospitals. They are primarily used on secreting wounds to minimize secretions and bacterial infections. [7]

More clinical research is needed to determine the effects bladderwrack may have on wound healing and skin health.

Bladderwrack Dosage Recommendations

The University of Michigan Health System reports the following bladderwrack dosages that have been used traditionally and in some human studies:

• 5-10 grams dried herb, in capsules, three times daily for thyroid problems, or gastritis
• 5 ml bladderwrack tincture, three times daily, for gastritis or heartburn
• 2 or more 400-500 mg capsules, 3-4 times daily, for intestinal inflammation
• 1 teaspoon dried herb in hot water to make tea, taken three times daily
• 1 teaspoon powder in 8 oz water, three times daily, for constipation [4]

Examine states, “the evidence in humans has noted that 500mg of bladderwrack (basic extract of the seaweed, not concentrated) appears to be bioactive.” [1]

Most supplements contain between 500-580 mg of bladderwrack per dosage. Some contain more, up to 1800 mg per dosage.

Some extracts are standardized for iodine content, but not all are. This amount of iodine will be listed on the label of supplements if they standardized to iodine content.

Different bladderwrack supplements contain different amounts of iodine and other bioactive constituents. The maximum recommended daily iodine intake is only 150 micrograms. Consider this when selecting a supplement. [4]

The optimal dosage of any supplement to take depends on many factors including the reason for taking the supplement, age, sex, and personal physiology. It is recommended that you speak with your doctor to help determine the best dosage for your needs.

Food Sources and Supplements

Bladderwrack is used widely in various cuisines. It is included in soups, stews, broth, curries, and salads.

Supplements are available as powders, capsules, tablets, tinctures, liquid extracts, and pieces of whole plant. [4]

Make sure supplements you are considering are organic, sustainably harvested, tested for contaminants, and non-genetically modified.

The NMCD reports there are over 1200 different bladderwrack supplements available on the market. Do your research and choose supplements from reputable manufacturers. [3]

It is recommended that when possible you choose supplements that have been standardized for iodine content, so you know how much is in each dosage.

Safety and Side Effects

The Natural Medicines Comprehensive Database rates bladderwrack as Possibly Safe for topical use.

It is rated as Possibly Unsafe for oral use primarily because of its high iodine content and potential contamination with heavy metals. [3]

High iodine intake may cause either an overactive or underactive thyroid gland in healthy adults.

The development of hyperthyroidism, hypothyroidism, or goiters (enlargement of the thyroid) is possible with prolonged use or high intake levels. Intake of high iodine levels can also exacerbate existing hyperthyroidism. [3]

In regard to heavy metal contamination, UMHS reports that bladderwrack that grows in heavy-metal-contaminated waters may contain high levels of toxic chemicals such as arsenic and lead.

Consumption of heavy metals is known to cause nerve damage, kidney damage, and other serious health problems. [4]

When supplements have been standardized for iodine content and come from water sources that are known to be low in heavy metal contamination, this seaweed is normally considered safe for most healthy people.

Do not use bladderwrack supplements or increase dietary intake of this plant extract if you are allergic to iodine.

Drug and Supplement Interactions

The NMCD reports that bladderwrack may have anticoagulant effects. It should not be used in conjunction with anticoagulant medications, herbs, or supplements due to the increased risk of bruising and bleeding. [3]

Some anticoagulants include:

• Angelica
• Aspirin
• Clopidogrel (Plavix)
• Clove
• Dashen
• Fenugreek
• Garlic
• Ginkgo biloba
• Heparin
• Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil)
• Panax ginseng
• Turmeric
• Warfarin (Coumadin) [3]

Because of its iodine content and potential effects on the thyroid, bladderwrack may reduce the effects of antithyroid drugs and cause hyperthyroidism.

Some antithyroid drugs include methenamine mandelate (Methimazole), methimazole (Tapazole), and potassium iodide (Thyro-Block). [3]

Talk to your doctor first about taking supplements if you have a bleeding disorder, infertility, iodine allergy, or thyroid dysfunction. [3]

Discontinue using bladderwrack at least 2 weeks before a scheduled surgery.

If you are interested in taking a bladderwrack supplement, then it is recommended that you speak with your doctor before beginning use. Your doctor will help you determine if this supplement is right for your needs.

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