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Seaweed, kelp, bladderwrack (Fucus vesiculosus)

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Also listed as: Seaweed, Kelp, Bladderwrack, Fucus vesiculosus
Related terms
Background
Evidencetable
Tradition
Dosing
Safety
Attribution

Related Terms
  • Acinetosporaceae (family), Acrochaetiaceae (family), agar, Akkesiphycaceae (family), alanine, Alariaceae (family), algas marinas (Spanish), algin, alginates, alginic acid, Aquamin®, arginine, Arthrocladiaceae (family), Ascophyllum nodosum, Ascoseriaceae (family), Asparagopsis armata (Harv.), aspartic acid, astaxanthin, beta-carotene, beta-glucans, Bifurcariopsidaceae (family), black-tang, bladder, bladder fucus, bladderwrack, Blasen-tang (German), Bonnemasoniaceae (family), brown algae, brown seaweed, brown seaweed extract, brown tropical seaweed, calcium, carrageenans, Carraguard®, Caulacanthaceae (family), Caulerpa lentillifera, Caulerpaceae (family), Cermiaceae (family), Champiaceae (family), chlorophyta, Chordaceae (family), Chordariaceae (family), Chordariopsidaceae (family), Choristocarpaceae (family), cobalamin, Codiaceae (family), Colaconemataceae (family), common seawrack, Corallinaceae (family), Costariaceae (family), Cruoriaceae (family), cut weed, Cutleriaceae (family), Cystocloniaceae (family), Cystophyllum fusiforme, Cystoseiraceae (family), Dasyaceae (family), Delesseriaceae (family), Delisea pulchra (Greville) Montagne, Desmarestiaceae (family), Dictyotaceae (family), dried nori, Dumontiaceae (family), Durvilleaeceae, Dyers fucus, (E)-9-oxooctadec-10-enoic acid (S6C), (E)-10-oxooctadec-8-enoic acid (S5C), Ecklonia cava, Ecklonia cava Kjellman, Ecklonia kurome, Ecklonia stolinifera, Ectocarpaceae (family), edible seaweed, Eisenia arborea, Eisenia bicyclis, Eucheuma cottonii, fatty acids, fermented tangle weed, fiber, Fucaceae (family), fucaxanthin, fuco negro (Spanish), fucoidans, fucophorethols, fucose, fucoxanthin, Fucus, Fucus distichus, Fucus evanescens, Fucus Plus®, Fucus vesiculosus, furanones, Furcellariaceae (family), galactose, Galaxauraceae (family), Gelidiaceae (family), GFS, Gigartinaceae (family), glucose, gluatmic acid, Gracilaria verrucosa, Gracilariaceae (family), green algae, green seaweed, glycine, Hai-ts'ao, Halymeniaceae (family), Heterochordariaceae (family), heterofucans, Himanthaliaceae (family), Hormosiraceae (family), iodine, iron, Ishigeaceae (family), Japanese kelp, Kappaphycus alvarezii, kelp, kelpware, knotted wrack, kombu, Laminaria cloustoni, Laminaria digitata, Laminaria japonica, Laminaria longicruris, Laminaria saccharina, Laminariaceae (family), lectins, Lessoniaceae (family), Liagoraceae (family), Lomentariaceae (family), Macrocystis pyrifera, magnesium, marine algae, marine brown algae, marine carotenoids, marine green algae, marine macroalgae, marine red algae, mekabu fucoidan, Meereiche (German), minerals, mucopolysaccharides, Nemastomataceae (family), Neoralfsiaceae (family), nori, ogonori, omega-3 fatty acids, omega-6 fatty acids, Padina gymnospora, Palmaria palmata, Palmariaceae (family), Petalonia bingamiae, Peyssonneliaceae (family), Phaeophyceae, phaeophyta, phenolics, phloroglucinol, phlorotannins, phosphonyl glycosyl ester diglycerides, phosphorus, Phyllophoraceae (family), Plocamiaceae (family), polyphenols, polysaccharides, popping wrack, Porphyra yezoensis, potassium, proline, protein, Pseudochordaceae (family), Pylaiellaceae (family), Quercus marina, Ralfsiaceae (family), raw nori, red alga, red algae, red fucus, red marine seaweed, red seaweed, Rhodomelaceae (family), Rhodophysemataceae (family), rhodophyta, Rhodymeniaceae (family), rockrack, rockweed, Sarcomeniaceae (family), Sargassaceae (family), Sargassum polycystum, Schweintang (German), Scytosiphonaceae (family), Scytothamnaceae (family), sea alga, sea algae, sea cabbage, sea kelp, sea lettuce, sea oak, sea wrack, seaware, seaweed, seaweed extract, seaweed soup, seeds of tangles, Seetang (German), sodium alginate, Solieriaceae (family), Spatoglossum schröederi, Sphacelariaceae (family), Sphaerococcaceae (family), Splachnidiaceae (family), Sporochnacaeae, Stylonemataceae (family), Stypocaulaceae (family), sulfate, sulfated polysaccharides, sulfonyl ester diglycerides, sulfuryl ester diglycerides, swine tang, tang, tangle weed, tannins, Tasmanian tororokombu, trace metals, tropical marine algae, Ulva lactuca, ulvans, Undaria pinnatifida, uronic acids, varech vésiculeux (French), ventol, vitamin B1, vitamin B2, vitamin B12, vitamin C, vitamin E, vraic, wakaame, wrack, xylose.
  • Select combination products: Xanthigen®-600 (300 milligrams of brown seaweed extract containing 2.4 milligrams of fucoxanthin and 300 milligrams of pomegranate seed oil).
  • Note: Overall, there is some disagreement over what is thought to be a seaweed over other types of algae. This bottom line focuses on the most common types of seaweed and does not include blue-green algae (Cyanobacteria), agar, or discussion of laminaria tents.

Background
  • Seaweeds are brown or green algae that live on or near the sea floor. Fucusvesiculosus, also called bladderwrack, is a brown seaweed that belongs to the Fucaceae family. The name sometimes refers to Ascophyllum nodosum, another brown seaweed. These species often make up kelp mixtures, along with other types of seaweed.
  • Bladderwrack has been used to treat thyroid gland problems and has been used in weight loss formulas. Some studies have shown that bladderwrack may thin the blood and lower blood sugar levels.
  • Information on the active ingredients of bladderwrack is lacking. Most of the effects of bladderwrack are shared by brown seaweed species as a whole. Overall, there is not enough evidence on the safety and effectiveness of seaweed in humans.

Evidence Table

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. GRADE *


Early research suggests that a product containing seaweed compounds and zinc may help improve mild acne. More research is needed.

C


A study found that a Chinese herbal formula containing seaweed lacked effects on HIV symptoms. More research on seaweed alone is needed.

C


Early studies suggest that seaweed may block the growth of bacteria and fungi. However, results are conflicting. There is a lack of human evidence.

C


Early research suggests that compounds of bladderwrack may have antioxidant effects. Antioxidant effects were found in some extracts of brown seaweed species such as Fucus vesiculosus and Ascophyllum nodosum, and Laminaria japonica. More research on seaweed is needed.

C


Although it has not been well studied in humans, early research suggests that brown seaweeds may have blood-thinning effects. Human evidence is limited. The effects of seaweed itself are not clear, and more research is needed.

C


A drug made with compounds from brown sea algae, omega-3 fatty acids, iodine, and chlorophyll may reduce symptoms of breast pain, premenstrual syndrome, and painful menstrual periods in people who have benign breast tumors. More research is needed.

C


The use of dressings containing algae has been studied for burns. However, the effects of seaweed on burns are still unclear. More research is needed.

C


Although it has not been well studied in humans, some research suggests that brown algae may block the growth of cancer cells. Human evidence is lacking, although one study in women after menopause found that eating seaweed raised the risk of thyroid cancer. More research is needed.

C


Although it has not been well studied in humans, some research suggests that seaweed extract may lower blood sugar levels. Human evidence is limited, though some studies found that eating a seaweed compound may lower blood sugar levels after meals. However, the results are conflicting, as other studies reported that bread enriched with seaweed lacked effects on blood sugar.

C


Bladderwrack contains iodine and has been used to treat goiter (enlarged thyroid). However, the effects of bladderwrack on this condition are not yet well understood. Bladderwrack may be a good source of iodine for people who do not have enough in their diets. Information on dosing, safety, and effectiveness are not available. There is not enough evidence to strongly support the use of bladderwrack.

C


Early research suggests that a mouthwash containing seaweed extract may help reduce bacteria and symptoms of gum disease. However, the effect of seaweed alone is unclear. More research is needed.

C


Eating jam that contains seaweed may help people who have heart disease in which there is a low supply of blood to the heart. More research is needed before conclusions can be made.

C


Early studies suggest that seaweed extract may block herpes viruses and that it may also promote healing and prevent symptoms in infected people. More research is needed.

C


Evidence on the effects of seaweed on blood pressure is lacking. More research is needed before conclusions can be made.

C


Early research found that seaweed may help people who have human T-lymphotropic virus, which is associated with leukemia. However, the effect of seaweed is still unclear, and more research is needed before conclusions can be made.

C


Diet therapy using a seaweed compound has been studied for use in people with kidney disease. However, further data are lacking, and more research is needed.

C


Seaweed has been studied as a potential treatment for some types of leg ulcers. However, information is limited, and more research is needed.

C


Early research found that brown seaweed may reduce the size of the waist in people who have metabolic syndrome. More research is needed before conclusions can be made.

C


Limited research suggests that a natural mineral supplement made from seaweed (AquaminT) may help people who have osteoarthritis (stiff and painful joints). However, the effects of seaweed alone are still unclear.

C


Early studies found that a seaweed compound may help improve endurance in college students. More research on seaweed alone is needed before conclusions can be made.

C


Limited research suggests that a seaweed-based gel (Carraguard®) may lack benefits for preventing sexually transmitted disease. More research is needed before conclusions can be made.

C


Some studies report that seaweed-based dressings and better blood sugar control may speed the healing of some skin diseases. The effects of different dressings and agents applied to the skin have been studied in people with skin grafts, and algae-based dressings have been studied for pressure ulcers. Further information is lacking, and the effect of seaweed alone is unclear.

C


Early research found that a fabric containing seaweed may help people who have atopic dermatitis (scaly and itchy rashes). However, the effect of seaweed alone is unclear, and more research is needed.

C


Bladderwrack and other seaweed products have been marketed for weight loss. Seaweed has been studied for this use in reviews and studies on fat burners and weight loss products. Further human research is needed to determine the safety and effectiveness of seaweed or seaweed extract alone.

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 for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)


Tradition / Theory

The below uses are based on tradition, scientific theories, or limited research. 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. There may be other proposed uses that are not listed below.

  • Allergies, antiviral, asthma, bladder inflammation, breast cancer, elimination of toxins, enlarged glands, exophthalmos (bulging eyeball), fatigue, flavoring, hair loss, heartburn, high cholesterol, immune function, indigestion, inflammation, iodine deficiency, laxative, malnutrition, menstrual disorders, myxedema (low thyroid hormone), neonatal jaundice, nerve disorders, nutritional deficiencies, orchitis (swollen or painful testes), parasites, Parkinson's disease, prostate enlargement, psoriasis, radiation side effects, rheumatism, sore throat, stool softener, swelling, tuberculosis, urinary tract tonic.

Dosing

Adults (18 years and older)

  • Information on the safety and effectiveness of any dose of seaweed is limited. Because bladderwrack may be contaminated with heavy metals, taking it may be potentially unsafe.
  • Seaweed has been taken by mouth in the whole dried plant form, or dried in capsules or tablets, or as an alcoholic liquid extract.
  • As an antioxidant, six capsules containing 250 milligrams of fermented sea tangle has been taken by mouth once daily, 30 minutes after a meal, for four weeks.
  • To treat metabolic syndrome, 4-6 grams of seaweed has been taken by mouth daily for up to eight weeks in two divided doses.
  • To improve thyroid function, 10 capsules containing five grams of seaweed (Alaria esculenta) and 475 micrograms of iodine have been taken by mouth daily for seven weeks.
  • Bladderwrack and seaweed patches made to be applied to the skin are sold commercially as weight loss products. However, information on accepted or tested doses is lacking.

Children (under 18 years old)

  • There is no proven safe or effective dose for bladderwrack 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.

Allergies

  • Avoid if allergic or sensitive to any seaweed, seaweed family, or any of their parts. Severe allergic reaction to Laminaria has been reported, with symptoms such as coughing, hives, shortness of breath, and swelling. Allergic skin reaction to Sargassum species and its content iodine has been reported. Skin blisters have also been reported.

Side Effects and Warnings

  • Bladderwrack is possibly safe when eaten at levels commonly found in the diet as part of an otherwise healthy diet by adults who are healthy, not allergic, and not pregnant or breastfeeding. Applying Carraguard® gel to the vaginal area or penis during sexual intercourse is possibly safe when used for up to 14 days, with some mild side effects possible, such as abdominal pain, bladder fullness, genital discomfort or warmth, and yellow vaginal discharge.
  • Seaweed may contain heavy metals such as arsenic, cadmium, and lead, which may increase the risk of heavy metal poisoning. Most side effects of seaweed appear to be related to high iodine content or heavy metal contamination, rather than to the seaweed itself. High doses of iodine may cause symptoms such as brassy taste, increased saliva, skin lesions, and stomach irritation.
  • Seaweed may also cause side effects such as broken blood vessels, changes in cholesterol levels, changes in skin coloring (due to high carotene levels in the blood), eye problems, fatigue, increased levels of some vitamins and minerals (such as calcium, magnesium potassium, and sodium), memory problems, nausea, nerve problems, stomach fullness, and vomiting.
  • Use cautiously in all people (children or adults) when using levels above those commonly found in the diet, due to the risk of iodine-related toxic effects, hemorrhage, cancer, mitochondrial toxicity, and vitamin A toxicity.
  • Use cautiously in all people (children or adults) when using raw seaweed, due to the risk of contamination with cholera.
  • Use cautiously in people who have or are at risk of having liver disease, due to the risk of liver swelling and inflammation.
  • Use cautiously in people who have heart disease or are taking drugs for heart disease, due to the risk of abnormal heart rhythm.
  • Use cautiously in people who have or are at risk of having skin disorders, due to the risk of high doses of iodine causing skin lesions or rash and severe acne.
  • Use cautiously in people who have iron deficiency, due to the risk of reduced iron absorption after long-term use.
  • Bladderwrack may lower blood sugar levels. Caution is advised in people with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Blood glucose levels may need to be monitored by a qualified healthcare professional, including a pharmacist, and medication adjustments may be necessary.
  • Bladderwrack may increase the risk of bleeding. Caution is advised in people with bleeding disorders or taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.
  • Use cautiously in people who have diarrhea, due to the potential laxative effects of seaweed as well as the risk of soft and increased feces.
  • Use cautiously in people who are underweight or are taking drugs for weight loss or stimulants, as seaweed may cause weight loss.
  • Use cautiously in people who have hormonal disorders or are taking hormonal agents, as bladderwrack may affect levels of some hormones.
  • Bladderwrack may cause low blood pressure. Caution is advised in people with low blood pressure or who are taking drugs or herbs and supplements that lower blood pressure.
  • Use cautiously in people using agents that may be toxic to the kidneys, due to the risk of kidney toxicity.
  • Use cautiously when kombu seaweed (Laminaria japonica) is taken by mouth at levels of 15 grams or more daily by healthy people who are not allergic, due to the risk of changes in levels of thyroid hormone.
  • Avoid if allergic or sensitive to any seaweed, seaweed family, or any of their parts. Severe allergic reaction to Laminaria has been reported, with symptoms such as coughing, hives, shortness of breath, and swelling. Allergic skin reaction to Sargassum species and its content iodine has been reported. Skin blisters have also been reported.
  • Avoid use of seaweed that has been stored for longer than 2-3 weeks or at high temperatures, due to the risk of organic toxic dust syndrome, a severe flu-like illness.
  • Avoid in people who have thyroid diseases (including hyperthyroidism, hypothyroidism, goiter, myxedema, or autoimmune thyroid disease) or in those who are taking thyroid hormones, due to potentially high iodine levels in seaweed.
  • Avoid in people who are taking lithium carbonate or amiodarone, due to potential hyperthyroidism.
  • Avoid in people who have heart failure or kidney failure, or people who are taking agents that increase urination, due to the potentially high sodium content of seaweed.
  • Avoid using nonsterilized seaweed as a dressing, due to the risk of wound infection.
  • Avoid in pregnant and breastfeeding women, due to potentially high iodine concentrations and contamination with heavy metals. There have been reports of increased iodine in the breast milk of women who ate seaweed, which may lead to thyroid problems in their infants.
  • Avoid using before radioiodine treatment, due to the need to reduce iodine intake before this treatment.
  • Avoid using seaweed or seaweed supplements from areas with known heavy metal or arsenic contamination, radiation exposure, or parasites (liver fluke, Fasciola hepatica), due to the risk of toxic side effects.
  • Avoid using seaweed supplements from untrustworthy sources, due to the risk of toxic ingredients.

Pregnancy and Breastfeeding

  • Bladderwrack is not recommended during pregnancy and breastfeeding, due to potentially high iodine concentrations and heavy metal contamination.
  • There have been reports of increased iodine in the breast milk of women who ate seaweed, which may lead to thyroid problems in their infants.

Attribution
  • This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Copyright © 2011 Natural Standard (www.naturalstandard.com)


The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.

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