Seaweed
Scientific Name(s): Ascophyllum, Chlorophceae (green algae), Chondrus crispus (Irish moss; red algae), Chondrus, Ecklonia, Fucus, Gelidium, Gracilaria, Hijikia fusiformis (hijiki; brown algae), Laminaria japonica (makonbu; brown algae), Laminaria (kombu; brown algae), Palmaria palmate (dulse; red algae), Phaeophyceae (red algae), Porphyra (nori, red algae), Pterocladia, Rhodophyceae (red algae), Saccharina (kombu; brown algae), Ulva fasciata (limu palahalaha; green algae), Undaria pinnatifida (wakame; brown algae)
Common Name(s): Algae, Brown algae, Brown seaweed, Dulse/dillisk, Egg wrack, Green algae, Hijiki, Irish moss/carrageenin, Kelp, Kombu/konbu, Makonbu, Nori, Red algae, Red seaweed, Sea grass, Sea lettuce, Sea spaghetti, Seaweed, Wakame
Medically reviewed by Drugs.com. Last updated on Aug 23, 2021.
Clinical Overview
Use
Clinical trials are generally lacking to support definitive therapeutic recommendations for seaweeds. However, seaweeds are an important nutritional source of minerals and elements and many are low in sodium. Applications may exist for use in cardiovascular conditions due to potential cholesterol reduction and appetite suppression. Alginates extracted from seaweed have been used in wound dressings.
Dosing
Clinical trials have used an oral dosage range of 4 to 12 g seaweed daily for up to 2 months.
Contraindications
Contraindications have not been identified.
Pregnancy/Lactation
Information regarding safety and efficacy in pregnancy and lactation is lacking.
Interactions
Patients taking warfarin and consuming a large quantity of food containing seaweed may experience a change in international normalized ratio (INR) because of seaweed's high vitamin K content.
Adverse Reactions
Contact dermatitis, goiter, and, occasionally, GI effects may occur.
Toxicology
Excessive intake of dried seaweed may result in increased serum thyroid-stimulating hormone (TSH). There have been case reports of carotenodermia (yellowing of the skin) with excessive seaweed consumption.
Botany
Seaweeds are marine algae, saltwater-dwelling, simple plants, including red (rhodophyta), brown (phaeophyta), and green (chlorophyta) algae. Most algae have root-like structures called holdfasts that anchor the plant to rocks and other substrates.1 While blue-green species of algae or aquatic plants, such as spirulina (cyanophyta), are actually photosynthetic bacteria. For information on Spirulina, see the individual monograph.
The Japanese term and common name for seaweed, kombu/konbu, should not be confused with kombucha. See Kombucha monograph.
History
For centuries, seaweed has inspired botanical, industrial, and pharmaceutical interest. Because of the high nutrient content, seaweed has been used as food throughout Asia.
Traditional Chinese medicine used hot water extracts of several types of seaweed in the treatment of cancer. Additionally, the Japanese and Chinese cultures used seaweed to treat goiter and other glandular problems as long ago as 300 BC.
The Romans used seaweed in the treatment of wounds, burns, and rashes.2 The Celts noted that seaweed contracted as it dried and then expanded with moisture. In Scotland during the 18th century, physicians used dried seaweed stem to successfully drain abdominal wall abscesses. They also inserted seaweed into the cervix in an attempt to treat dysmenorrhea. Many reports outline the use of seaweed to induce abortion. Seaweed was employed intravaginally for vaginal atresia and was used urethrally and rectally for strictures.2, 3,
