Seaweed, Kelp, Bladderwrack : Safety

by MedlinePlus

(Page 2 of 2)

Allergies

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. There are reports of increased thyroid activity (hyperthyroidism) and decreased thyroid activity (hypothyroidism) from ingestion of seaweed/kelp products. 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. One case report of 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.

Based on animal study, 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.

Based on laboratory study, 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

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.

Based on animal study, 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.

Based on laboratory study, 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.

Interactions with Herbs and Dietary Supplements

Based on animal study, 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. Possible examples include: Aloe vera, American ginseng, bilberry, bitter melon, burdock,fenugreek, fish oil, gymnema, horse chestnut seed extract (HCSE), marshmallow, milk thistle, Panax ginseng, rosemary, Siberian ginseng, stinging nettle and white horehound. In theory, the high iodine content of bladderwrack may interfere with the function of herbs or supplements that act on the thyroid. Other endocrine hormones, estrogen and progesterone levels may be affected and therefore bladderwrack may interacted with hormonal herbs and supplements.

Based on laboratory study, 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. Some examples include: alfalfa, American ginseng, angelica, anise, Arnica montana , asafetida, aspen bark, bilberry, birch, black cohosh, bogbean, boldo, borage seed oil, bromelain, capsicum, cat's claw, celery, chamomile, chaparral, clove, coleus, cordyceps, danshen, devil's claw, dong quai, evening primrose, fenugreek, feverfew, flaxseed/flax powder (not a concern with flaxseed oil), ginger, grapefruit juice, grapeseed, green tea, guggul, gymnestra, horse chestnut, horseradish, licorice root, lovage root, male fern, meadowsweet, nordihydroguairetic acid (NDGA), onion, papain, Panax ginseng, parsley, passionflower, poplar, prickly Ash, propolis, quassia, red clover, reishi, Siberian ginseng, sweet clover, rue, sweet birch, sweet clover, turmeric , vitamin E, white willow, wild carrot, wild lettuce, willow, wintergreen, and yucca.

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. Possible Laxative herbs include alder buckthorn, aloe dried leaf sap, black root, blue flag rhizome, butternut bark, dong quai, European buckthorn, eyebright, cascara bark, castor oil, chasteberry, colocynth fruit pulp, dandelion, gamboges bark, horsetail, jalap root, manna bark, plantain leaf, podophyllum root, psyllium, rhubarb, senna, wild cucumber fruit, and yellow dock root.

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.

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