Seaweed, kelp, bladderwrack

Fucus vesiculosus is a brown seaweed that grows on the northern coasts of the Atlantic and Pacific oceans, and the North and Baltic seas. Its name is sometimes used for Ascophyllum nodosum, which is another brown seaweed that grows alongside Fucus vesiculosus . These species are often included in kelp preparations along with other types of seaweed.

The Vietnamese consume seaweed as food in various forms: raw as salad and vegetable, pickle with sauce or with vinegar, relish or sweetened jellies and also cooked for vegetable soup. As herbal medicine, seaweed is has been used for traditional cosmetics, treatments for cough, asthma, hemorrhoid, boils, goiters, stomach ailments, urinary diseases, reducing the incidence of tumors, ulcers and headaches. Although Vietnam has an abundance of algae floral with total number of species is estimated to be nearly 1,000 species of which there are 638 species of marine algae identified.

Synonyms

Black-tang, bladder, bladder fucus, bladderwrack, Blasen-tang, brown algae, common seawrack, cut weed, Dyers fucus, edible seaweed, fucoidan, fucoxantin, Fucus, green algae, Hai-ts'ao, kelp, kelpware, knotted wrack, Meereiche, Quercus marina, popping wrack, red algae, red fucus, rockrack, rockweed, schweintang, sea kelp, sea oak, seetang, seaware, seaweed, sea wrack, swine tang, tang, Varech vesiculeux, vraic, wrack.

Evidence

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Uses based on scientific evidence	Grade^*
Antibacterial/antifungal Laboratory study suggests antifungal and antibacterial activity of bladderwrack. However, there are no reliable human studies to support use as an antibacterial or antifungal agent.	C
Anticoagulant (blood-thinner) Laboratory study has found anticoagulant properties in fucans or fucoidans, which are components of brown algae such as bladderwrack. However, there are no high quality human studies available to support this use.	C
Antioxidant Laboratory study suggests antioxidant activity in fucoidans, which are components in some brown algae. However, there are no high quality human studies available to support use as an antioxidant.	C
Cancer Several brown algae, including bladderwrack ( Fucus vesiculosus ), appear to suppress the growth of various cancer cells in animal and laboratory studies. However, currently there are no reliable human studies available to support a recommendation for use in cancer.	C
Diabetes Based on animal research, extracts of bladderwrack may lower blood sugar levels. However, there are no reliable human studies available to support a recommendation for use in diabetes.	C
Goiter (thyroid disease) Bladderwrack contains variable levels of iodine. As a result, it has been used to treat thyroid disorders such as goiter. While the evidence does suggest thyroid activity, there is not enough research to support this use of bladderwrack.	C
Weight loss Bladderwrack and other seaweed products are often marketed for weight-loss. However, safety and effectiveness have not been studied in humans.	C

*Key to grades
A: Strong scientific evidence for this use;
B: Good scientific evidence for this use;
C: Unclear scientific evidence for this use;
D: Fair scientific evidence against this use;
F: Strong scientific evidence against this use.

Grading rationale

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Antiviral, atherosclerosis, arthritis, benign prostatic hypertrophy (BPH), bladder inflammatory disease, eczema, edema, enlarged glands, fatigue, heart disease, hair loss, heartburn, herpes simplex virus, high cholesterol, kidney disease, laxative, lymphadenoid goiter, lymphoma, malnutrition, menstruation irregularities, obesity, parasites, psoriasis, radiation protection, rheumatism, sore throat, stool softener, stomach upset, swollen or painful testes, ulcer, urinary tract tonic.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older)

Soft capsules (alcohol extract) in doses of 200 to 600 milligrams daily have been taken by mouth. Tablets have also been used, initially taken three times per day and gradually increased to 24 tablets per day. 16 grams of bruised plant mixed with one pint of water has been used, administered in 2 fluid ounce doses three times per day, or an alcoholic liquid extract in a dose of 4 to 8 milliliters before meals.

Topical (on the skin) bladderwrack and seaweed patches are sold commercially as weight loss products, although there are no commonly accepted or well tested doses.

Children (under 18 years old)

There is not enough scientific evidence to recommend safe use of bladderwrack in children. Because of the iodine content and potential for contamination with heavy metals, it may be inadvisable for use in children.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergy/hypersensitivity to Fucus vesiculosus or any of its components, or iodine sensitivity may occur.

Side Effects and Warnings

Most adverse effects appear related to high iodine content, heavy metal or other contamination of bladderwrack preparations, rather than to the seaweed itself. Because of the potential contamination of bladderwrack with heavy metals, its consumption should always been considered potentially unsafe.

Based on the known effects of iodine toxicity, the high iodine content in bladderwrack may lead to abnormal thyroid conditions. In theory, bladderwrack may increase or decrease blood thyroid hormone levels. In addition, acne-type skin lesions may occur, and there are reports of severe acne exacerbations with use of kelp. Iodine may also cause a brassy taste, increased salivation, and stomach irritation.

Reports of kidney and nerve toxicity have occurred in persons taking seaweed/kelp, attributed to high levels of arsenic. Abnormal bleeding and reduced blood platelet count was attributed to contaminants in a kelp product. Bladderwrack may contain vitamins and minerals, calcium, magnesium, potassium, and sodium, and may increase blood levels.

Extracts of bladderwrack may cause lowered blood sugar. Caution is advised in patients with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Serum glucose levels may need to be monitored by a healthcare provider, and medication adjustments may be necessary.

Bladderwrack may have blood-thinning (anticoagulant) properties. Abnormal bleeding, petechiae, and autoimmune thrombocytopenic purpura with dyserythropoiesis have been reported. Caution is advised in patients with bleeding disorders or taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.

Laxative properties have traditionally been attributed to chronic use of bladderwrack and other brown seaweeds, and may be due to the component alginic acid, present in many laxative agents.

Pregnancy and Breastfeeding

Bladderwrack is not recommended during pregnancy or lactation due to lack of reliable scientific information, and because of the presence of high levels of iodine and possible heavy metal contamination.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

Interactions with Drugs

In theory, the high iodine content of bladderwrack may interfere with the function of drugs that act on the thyroid such as levothyroxine (Synthroid®, Levoxyl®). Use of bladderwrack and amiodarone may alter thyroid function due to high iodine levels in both agents. Use of iodine-containing agents such a bladderwrack or kelp may alter thyroid function when used with lithium. Other endocrine hormones, estrogen and progesterone levels may be affected and therefore bladderwrack may interacted with hormonal drugs.

Extracts of bladderwrack may cause lowered blood sugar. Caution is advised when using medications that may also lower blood sugar. Patients taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare provider. Medication adjustments may be necessary.

Bladderwrack may have blood-thinning (anticoagulant) properties. Therefore, bladderwrack may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®) .

Laxative properties have traditionally been attributed to chronic use of bladderwrack and other brown seaweeds, and may be due to the component alginic acid, present in many laxative agents. Combination with laxatives may cause an additive effect. In theory, due to thyroid stimulant properties, bladderwrack may cause additive effects if taken with stimulants. The presence of heavy metal contaminants in bladderwrack preparations, including arsenic, cadmium, chromium, or lead, may increase the risk of kidney toxicity if taken with drugs that cause kidney damage. Bladderwrack may interact with diuretics.

Interactions with Herbs and Dietary Supplements

Extracts of bladderwrack may lower blood sugar levels. Caution is advised when using herbs or supplements that may also lower blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.

Bladderwrack may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba , and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.

In theory, due to thyroid stimulant properties, bladderwrack may cause additive effects if taken with herbs or supplements with stimulant-type activity, such as caffeine, guarana, or ephedra (ma huang). The presence of heavy metal contaminants in bladderwrack preparations, including arsenic, cadmium, chromium, or lead, may increase the risk of kidney toxicity if taken with herbs or supplements that can cause kidney damage.

In theory, bladderwrack may decrease iron absorption, especially if ingested for a prolonged period of time. Bladderwrack preparations contain variable levels of calcium, magnesium, potassium, sodium, vitamins, and minerals and may therefore increase blood levels. Bladderwrack may interact with diuretics.