Bladderwrack

Effects and Benefits

Core Identification

Common Names:
- Bladderwrack
- Kelp (loosely applied, though technically refers to larger seaweeds)
- Rockweed
- Sea oak
- Black tang
- Cutweed
- Bladder fucus
- Sea wrack
- Kelp-ware
- Quercus marina
- Dyer's fucus
- Hai-ts'ao (Chinese)
- Blasentang (German)
- Seetang (German)

Latin Name: Fucus vesiculosus

Category: Herb (Sea Vegetable)

Uses

Traditional Uses

• Thyroid support and goiter treatment - European herbal medicine, 1812 onwards (following iodine discovery)
• Weight loss support - Western herbal medicine, 1860s onwards; Dr. Duchesne-Duparc documented personal weight loss of 5¼ pounds in one week using bladderwrack pills
• Rheumatic conditions - European folk medicine (as liniment for external use)
• Arthritis inflammation - Traditional use as poultice
• Remineralization tonic - European herbal tradition; used to replenish mineral stores
• Nutritive food source - Historical use in coastal communities; cattle in Hebrides Islands fed on seaweed during winter
• Prostate health - Traditional use for enlarged prostate, swollen testes
• Breast cancer prevention - Traditional use in Japan

Modern Uses

• Hypothyroidism (iodine deficiency type) - Thyroid stimulation and hormone support | Research quality: Moderate
• Key findings: Bladderwrack provides significant iodine, essential for thyroid hormone production. It also supplies di-iodotyrosine (DIT), a direct precursor to thyroid hormones T3 and T4. Most effective when hypothyroidism results from iodine deficiency rather than autoimmune causes. Experimental studies from 1910 demonstrated stimulatory activity on the thyroid gland beyond iodine's effects alone. May quickly help reverse symptoms of mild thyroid underactivity including low vitality, depressed mood, weight gain, and cold sensitivity. Positive results have been obtained in both hypothyroidism and Graves' hyperthyroidism cases.

• Source citations: Western Materia Medica II; Bone - Clinical Guide to Blending Liquid Herbs; DK Herbal Remedies; Gladstar - Planting the Future; Hoffman - Holistic Herbal

• Weight management support - Metabolic support through thyroid stimulation | Research quality: Preliminary to Moderate

• Key findings: Traditional use for weight loss where thyroid underactivity contributes to metabolic slowdown. The alginates provide bulking action, and thyroid stimulation may increase metabolic rate. Most effective in cases linked to iodine deficiency. Eclectic texts noted benefit only when diet was deficient in iodine. In a controlled clinical trial, obese volunteers taking bladderwrack extract in addition to a controlled diet achieved significantly greater average weight loss than those on diet alone. Works best in "cold, torpid individuals with cold, clammy skin, loose and flabby rolls of fat, with relaxed pendulous abdomen."

• Source citations: Bone - Clinical Guide to Blending Liquid Herbs; Breverton's Complete Herbal; Western Materia Medica II

• Prostate support - Normalizing enlarged prostate | Research quality: Traditional/Preliminary

• Key findings: Bladderwrack at 3-5 grams daily can normalize a swollen prostate, especially in early stages. Best results occur when small pieces of whole plant are eaten with food. Encapsulated powdered dried bladderwrack is second best. Alcohol and hot water extracts seem least effective.

• Source citations: Gladstar - Planting the Future; Western Materia Medica II

• Women's reproductive health - Hormonal and breast health support | Research quality: Preliminary

• Key findings: Bladderwrack can extend the menstrual cycle and has anti-estrogenic effects in premenopausal women. It may increase progesterone levels. Kelps help prevent, reduce, and eliminate fibrocystic breast tissue, ovarian cysts, uterine fibroids, menstrual cramps, and hot flashes. Used in Japan to prevent breast cancer and helps clear fibrocystic breast disease. The high mineral content helps prevent osteoporosis and promotes fertility.

• Source citations: Western Materia Medica II; Soule - The Woman's Handbook of Healing Herbs; McIntyre - Complete Herbal Tutor

• Rheumatic and arthritic conditions - Internal and topical use for joint pain | Research quality: Traditional/Preliminary

• Key findings: Used internally and topically for rheumatism and rheumatoid arthritis. Traditional Eclectic use for arthritic symptoms, particularly when linked to low thyroid function. An external poultice or soaking in bladderwrack baths (the hotter the better) can relieve sore joints and achy muscles; may also stimulate cartilage regrowth. European thalassotherapy spas and seaweed baths have been traditional methods for relieving muscle and joint pain.

• Source citations: Bone - Clinical Guide to Blending Liquid Herbs; McIntyre - Complete Herbal Tutor; Gladstar - Planting the Future; Hoffman - Holistic Herbal

• Antiviral activity (fucoidan) - Herpes, HIV, and other viruses | Research quality: Preliminary

• Key findings: Fucoidan, a sulfated polysaccharide in bladderwrack, is a potent antiviral that inhibits virus attachment to host cells, cell penetration, and viral intracellular replication. Shows strong activity against herpes simplex 1, HIV-1, hepatitis C, and human cytomegalovirus. The polysaccharide or glycoprotein is responsible for reducing both herpes zoster and genital herpes outbreaks.

• Source citations: Gladstar - Planting the Future; Western Materia Medica II; Bone - Clinical Guide to Blending Liquid Herbs

• Immune support - Antioxidant and immunostimulant | Research quality: Preliminary

• Key findings: Bladderwrack contains the highest antioxidant activity of edible seaweeds, possibly due to fucoxanthin. Its antioxidants remove free radicals and help reduce cellular damage. The polysaccharides are immunostimulant. Fucoidan shows strong antitumor activity by enhancement of inflammatory responses and upregulation of leukocytic phagocytosis. Has antibacterial and antifungal properties.

• Source citations: McIntyre - Complete Herbal Tutor; Chevallier - Encyclopedia of Herbal Medicine; Gladstar - Planting the Future

• Digestive support - Demulcent and mild laxative | Research quality: Traditional

• Key findings: Acts as demulcent to soothe the digestive tract. Used for heartburn, gastritis, peptic ulcers, and indigestion. The alginates have water-absorbing properties with acid-neutralizing, buffering action and hemostatic properties favored for ulcer treatment. Contains nondigestible fiber useful as mild laxative for constipation. Supports gut flora and has been used for Candida and intestinal worms.

• Source citations: McIntyre - Complete Herbal Tutor; Western Materia Medica II

• Cardiovascular support - Arterial health, cholesterol, and blood thinning | Research quality: Traditional/Preliminary

• Key findings: Traditionally supports elasticity and overall health of arteries. Reduces cholesterol levels through inhibiting bile acid absorption. The fucoidans have anticoagulant, fibrinolytic, and antiplatelet adhesion effects. Low molecular weight fucoidan fraction demonstrated potent anticoagulant and fibrinolytic properties in vitro. May help with hypotension, hypertension, and anemia.

• Source citations: DK Herbal Remedies; McIntyre - Complete Herbal Tutor; Bone - Clinical Guide to Blending Liquid Herbs; Western Materia Medica II

• Skin conditions and anti-aging - Internal and topical use | Research quality: Preliminary

• Key findings: By supporting toxin clearance, bladderwrack is used for chronic skin complaints including boils, eczema, psoriasis, and herpes. Clinical studies have shown that topical administration of bladderwrack extract can reduce skin thickness and other signs of aging. Bladderwrack extract promoted collagen gel contraction by increasing integrin molecules on fibroblasts in dermal tissue models.

• Source citations: McIntyre - Complete Herbal Tutor; Western Materia Medica II; Bone - Clinical Guide to Blending Liquid Herbs

• Wound healing - Fucoidan for tissue repair | Research quality: Preliminary

• Key findings: Fucoidan has been shown to stimulate transforming growth factor (TGF)-beta to increase fibroblast proliferation, suggesting usefulness for wound healing. Polysaccharides from bladderwrack demonstrated strong adhesion to epithelial tissue. Pretreatment with fucoidan significantly reduces postsurgical complications.

• Source citations: Western Materia Medica II; Gladstar - Planting the Future

• Urinary system support - Diuretic and anti-inflammatory | Research quality: Traditional

• Key findings: As a diuretic, aids toxin elimination. Used for edema, benign prostatic hypertrophy, cystitis, and urethritis. Eclectics noted it reduced renal congestion and bladder inflammation.

• Source citations: McIntyre - Complete Herbal Tutor; Bone - Clinical Guide to Blending Liquid Herbs

• Radiation protection - Binding radioactive elements | Research quality: Preliminary

• Key findings: Sodium alginate from bladderwrack reduces absorption of radioactive strontium and other radioactive divalent metals (barium, cadmium, manganese, zinc, mercury) from the gastrointestinal tract. Barium levels reduced to 3% of control value; cadmium and manganese reduced by about 50%. Loading the thyroid with healthy iodine-127 may help prevent uptake of radioactive iodine-131.

• Source citations: Western Materia Medica II; McIntyre - Complete Herbal Tutor; Soule - The Woman's Handbook of Healing Herbs

• Nutritional supplementation - Mineral and vitamin source | Research quality: Established

• Key findings: Concentrated source of minerals including iodine, potassium, magnesium, calcium, iron, zinc, copper, chromium, selenium, silica, manganese, and phosphorus. For vegans, supplies vital vitamin B12 otherwise found almost exclusively in animal products. Also contains vitamins A (as beta-carotene), B2, C, D, and E. Reported to be very beneficial to sensory nerves, membranes surrounding the brain, spinal cord, and brain tissue.
• Source citations: Breverton's Complete Herbal; McIntyre - Complete Herbal Tutor; Western Materia Medica II

Active Compounds

Primary Active Ingredients:
- Iodine (0.01-0.02%) - Essential trace mineral for thyroid hormone synthesis; bladderwrack provides both free and protein-bound iodide
- Di-iodotyrosine (DIT) - Direct precursor to thyroid hormones T4 (thyroxine) and T3 (triiodothyronine), making bladderwrack particularly effective for thyroid support
- Alginic acid - Hydrophilic polysaccharide with water-absorbing properties; used as bulking agent with acid-neutralizing and hemostatic properties
- Fucoidan/Fucoidin - Sulfated polysaccharide with anticoagulant (heparin-like), antiviral, antitumor, and wound-healing activity; all human cells have receptor sites for fucose (end-group sugar on fucoidan)
- Laminarin - Storage polysaccharide
- Mannitol - Sugar alcohol
- Polyphenols - Antioxidant compounds; bladderwrack has highest antioxidant activity of edible seaweeds
- Fucoxanthin - Carotenoid pigment with antioxidant properties
- Zeaxanthin - Carotenoid pigment
- Minerals - Calcium, chromium, germanium, iron, phosphorus, potassium, bromine, magnesium, manganese, selenium, silica, zinc
- Vitamins - Beta-carotene (pro-vitamin A), B2, B12, C, D, E

Dosage Information

Standard Dosage:
- Form: Capsule or tablet
- Amount: 1,000-2,000 mg per day
- Frequency: Twice daily

Infusion:
- Pour a cup of boiling water onto 2-3 teaspoonfuls of the dried herb
- Steep for 10 minutes
- Drink three times daily
- Source: Hoffman - Holistic Herbal

Therapeutic Dosage:
- Form: Dried seaweed (whole plant preferred)
- Amount: 3-5 g daily for prostate support; 5-10 g dried thallus three times daily for thyroid
- Purpose: Hypothyroidism, prostate health, or other therapeutic uses
- Duration: Use under professional guidance; monitor thyroid function
- Note: Best results from eating small pieces of whole plant with food; encapsulated powder second best; alcohol and hot water extracts least effective

Tincture:
- Dried seaweed (1:3, 45% alcohol): 1-3 mL up to 4 times daily
- Source: Easley - The Modern Herbal Dispensatory

Professional/Practitioner Dosage:
- Liquid Extract (1:1): 4.5-8.5 mL per day (30-60 mL per week)
- Source: British Herbal Pharmacopoeia 1983, British Herbal Compendium 1992; Bone - Clinical Guide to Blending Liquid Herbs

Fucoidan Extract (Dr. Ryan Drum method):
- Boil/simmer 1 quart water with 1 oz (about 1½ cups) dried brown seaweed for 20-40 minutes
- Drink daily for 1-2 weeks pre-surgically or after tissue wounding
- Source: Western Materia Medica II

Maximum Safe Dosage:
- Daily iodine maximum: Do not exceed 150 μg iodine per day from all sources without medical supervision
- Warning threshold: Excessive dosage may lead to hyperthyroidism, tremor, increased pulse rate, and elevated blood pressure
- Use only quality-tested products to avoid arsenic and other heavy metal contamination

Bioavailability Notes:
- Best taken in capsule or tablet form due to strong, unpleasant oceanic taste
- Whole plant eaten with food provides best results
- The minerals and iodine in bladderwrack are generally well-absorbed
- Alginates have better bulking effect in neutral/alkaline environment (do not swell well in acid)

How to Take It

Timing:
- Best time of day: Morning or with meals
- With food or on empty stomach? With food preferred for improved tolerance and absorption
- Specific timing notes: Take consistently at the same time each day for thyroid support; effects on thyroid function develop gradually over weeks

Form Recommendations:
- Whole plant pieces with food - Most effective method according to Dr. Ryan Drum
- Capsules/tablets - Most convenient and palatable; second most effective
- Infusion - Traditional preparation; moderate effectiveness
- Tincture/extract - Least effective for therapeutic purposes but useful for convenience

External Use:
- Poultice - Apply to arthritic joints for pain relief
- Bath - Add strong infusion to hot bath water for muscle/joint aches and cellulite
- Compress/oil - Apply to reduce inflammation in joints and bruises

Synergies - What It Works Well With

Complementary Supplements:
1. Selenium - Essential cofactor for thyroid hormone conversion (T4 to T3) | Combine for comprehensive thyroid support
2. Tyrosine - Amino acid precursor to thyroid hormones | Combine for enhanced thyroid hormone production
3. Ashwagandha - Adaptogen that may support thyroid function through different mechanisms | Combine for holistic thyroid and adrenal support
4. Zinc - Supports thyroid hormone synthesis and metabolism | Combine for mineral-balanced thyroid support
5. B-Vitamins - Support energy metabolism | Combine for overall metabolic support

Traditional Goiter Formulas (Bartram):

Hard Goiter Formula:
- Combine liquid extracts: Bladderwrack 2 parts; Fringe Tree 1 part; Poke root ½ part
- One 5 mL teaspoon in water three times daily

Soft Goiter Formula:
- Combine liquid extracts: Bladderwrack 2 parts; Blue Flag root ½ part; Horsetail 1 part
- One 5 mL teaspoon in water three times daily

Goiter with Severe Nervous Agitation:
- Combine liquid extracts: Bladderwrack 2 parts; Valerian 1 part; Passion flower 1 part
- 30-60 drops in water three times daily

Cyst on Thyroid Gland:
- Combine liquid extracts: Bladderwrack 2 parts; Clivers 2 parts; Fringe Tree 1 part
- One 5 mL teaspoon in water three times daily

Source: Bartram - Encyclopedia of Herbal Medicine

Avoidance - What NOT to Combine With

Supplement Interactions:
1. Other iodine-containing supplements - Risk of excessive iodine intake | May cause thyroid dysfunction
2. Strontium supplements - Bladderwrack's alginate content significantly reduces strontium absorption (up to 4-fold reduction) | Take several hours apart if using both
3. Anticoagulant/antiplatelet herbs (angelica, clove, danshen, fenugreek, feverfew, garlic, ginger, ginkgo, Panax ginseng, red clover, turmeric) - Bladderwrack has heparin-like anticoagulant effects | Increased bleeding risk

Drug Interactions:
1. Thyroid medications (Levothyroxine/Synthroid) - Bladderwrack may alter thyroid hormone levels | May require medication dose adjustment | Severity: Moderate to Severe
2. Antithyroid medications (Methimazole/Tapazole, potassium iodide) - Additive hypothyroid effects | Risk of excessive thyroid suppression | Severity: Moderate
3. Lithium - Lithium potentiates the hypothyroid action of iodine | Increased risk of hypothyroidism | Severity: Moderate
4. Anticoagulants/Blood thinners (Warfarin, Heparin, Aspirin, Plavix) - Bladderwrack has anticoagulant effects | Increased bleeding and bruising risk | Severity: Moderate to Severe
5. NSAIDs (Ibuprofen, Naproxen, Diclofenac) - Both affect platelet function | Increased bleeding risk | Severity: Mild to Moderate
6. Insulin and antidiabetic drugs - Bladderwrack may lower blood sugar | Monitor for hypoglycemia | Severity: Mild to Moderate

Food Interactions:
- No significant food interactions known beyond general iodine considerations

Safety Information

Contraindications:
- Hyperthyroidism/overactive thyroid - Iodine content will worsen condition
- Graves' disease - Contraindicated
- Pregnancy - Contraindicated; may affect fetal thyroid development
- Lactation/breastfeeding - Contraindicated; iodine passes into breast milk
- Cardiac problems associated with hyperthyroidism - Contraindicated
- Hashimoto's thyroiditis - Use cautiously; high iodine intake has caused or worsened this condition
- Surgery - Discontinue 2 weeks before due to anticoagulant effects
- Weak or deficient spleen/stomach (TCM) - Generally contraindicated
- Low-sodium diet - Consult practitioner before use (high salt content)

Side Effects (rare at normal doses):
- Transient hyperthyroidism (at iodine intakes of 2.8-4.2 mg/day)
- Elevated TSH levels
- Subclinical hypothyroidism (paradoxically, with excessive intake)
- Allergic reactions including edema (at high iodine doses)
- Prolonged use may cause acne (due to high iodine content)
- Excessive dosage: tremor, increased pulse rate, elevated blood pressure

Fertility Caution:
Fucoidan may have antifertility effects by preventing the binding of sperm to egg. Those trying to conceive should be aware of this potential effect.

Heavy Metal Contamination Warning:
Bladderwrack naturally accumulates arsenic and other heavy metals from seawater. Cases of kidney damage and blood disorders have been linked to contaminated kelp products. Use only products from reputable manufacturers with third-party testing. Do not collect kelp where levels of cadmium and/or mercury in water are known to be high.

Lab Test Interactions:
- Thyroid function tests (TSH, T4, radioactive iodine uptake) - May affect results
- aPTT (activated partial thromboplastin time) - May increase results due to heparin-like constituents
- Estradiol - May lower levels in premenopausal women
- Progesterone - May increase levels in premenopausal women

Long-Term Use:
- Safety of prolonged use: Limited data on long-term supplementation; not recommended for extended use without monitoring
- Monitoring recommendations: Thyroid function tests (TSH, T3, T4) every 3-6 months if using therapeutically
- Cycle recommendations: Some practitioners recommend periodic breaks; consult healthcare provider

Primary Uses At-a-Glance

Primary: Hypothyroidism (iodine-deficiency type), goiter, sluggish metabolism, weight management, iodine deficiency, mineral supplementation

Secondary: Enlarged prostate, fibrocystic breast, rheumatic conditions, digestive support, antiviral (herpes), skin conditions, radiation protection, women's hormonal health

Sources

Local Library:
- Bartram, Thomas - Bartrams Encyclopedia of Herbal Medicine: Goiter formula combinations (hard, soft, nervous, cyst), traditional indications
- Bone, Kerry - A Clinical Guide to Blending Liquid Herbs: Actions, contraindications, drug interactions, professional dosing, traditional Eclectic uses, pregnancy warnings, side effects, heavy metal concerns, clinical studies (weight loss trials, anti-HIV activity, collagen/fibroblast research)
- Breverton, Terry - Breverton's Complete Herbal: Historical iodine discovery, traditional uses, Dr. Duchesne-Duparc's weight loss experiments, B12 content for vegans
- Chevallier, Andrew - Encyclopedia of Herbal Medicine: Constituents, immunostimulant properties, metabolic effects, rheumatic uses
- Duke, James A. - Handbook of Medicinal Herbs: Actions list, dosages, Commission E status, safety classification
- Easley, Thomas - The Modern Herbal Dispensatory: Tincture and capsule dosing, warnings for Hashimoto's, energetics, fucoidan properties
- Gladstar, Rosemary - Planting the Future: Prostate support (Dr. Ryan Drum's recommendations), fucoidan antiviral research, form effectiveness hierarchy, thyroid disorders, postsurgical benefits
- Hoffman, David - Holistic Herbal: Actions, indications, infusion preparation and dosage
- Hopman, Ellen Evert - Secret Medicines From Your Garden: Contraindications (blood thinners, pregnancy, high blood pressure, lithium, surgery, hyperthyroidism)
- McIntyre, Anne - The Complete Herbal Tutor: Comprehensive constituents list, actions, digestive uses, skin conditions, urinary system, cardiovascular, radiation binding, immune support, women's reproductive uses, external applications
- Soule, Deb - The Woman's Handbook of Healing Herbs: Women's health uses (fibrocystic breast, ovarian cysts, uterine fibroids, menstrual cramps, hot flashes), radiation protection, mineral content for osteoporosis
- Western Materia Medica II (Wild Rose College): Constituents, medical research, history, thyroid physiology, Dr. Ryan Drum's DIT research, radiation protection, fucoidan research, menstrual/hormonal effects, wound healing, skin aging, energetics, contraindications
- Wood, Matthew - The Earthwise Herbal Vol. 1: Traditional indications, specific uses, torpid obesity, lymphatic and kidney cleansing
- DK - Herbal Remedies (2007): Safety ratings, traditional and research ratings, key actions, weight loss and thyroid applications
- Herb-Drug-Nutrient Interaction (Wild Rose College): Complete drug interaction profile, lab test effects, supplement interactions

General Knowledge:
- Core Identification framework, Description structure
- Commission E monograph status (thallus not approved for therapeutic use; permitted as laxative)
- AHP safety classification (Class 2b, 2c, 2d - not for long-term use, especially in hyperthyroids)