Edible seaweed

Edible seaweed, or sea vegetables, are seaweeds that can be eaten and used for culinary purposes.^[1] They typically contain high amounts of fiber.^[2][3] They may belong to one of several groups of multicellular algae: the red algae, green algae, and brown algae.^[2] Seaweeds are also harvested or cultivated for the extraction of polysaccharides^[4] such as alginate, agar and carrageenan, gelatinous substances collectively known as hydrocolloids or phycocolloids. Hydrocolloids have attained commercial significance, especially in food production as food additives.^[5] The food industry exploits the gelling, water-retention, emulsifying and other physical properties of these hydrocolloids.^[6]

Most edible seaweeds are marine algae whereas most freshwater algae are toxic. Some marine algae contain acids that irritate the digestion canal, while others can have a laxative and electrolyte-balancing effect.^[7] Most marine macroalgae are nontoxic in normal quantities, but members of the genus Lyngbya are potentially lethal.^[8] Typically, poisoning is caused by eating fish which have fed on Lyngbya or on other fish which have done so;^[8] this is called ciguatera poisoning.^[8] Handling Lyngbya majuscula can also cause seaweed dermatitis.^[9] Some species of Desmarestia are highly acidic, with vacuoles of sulfuric acid that can cause severe gastrointestinal disorders.^[8]