Bladderwrack (Fucus vesiculosus) has a long history of use dating back at least to the early 1300s. King Denis of Portugal, known as the Farmer King, regulated the harvest of cast ashore seaweeds, including bladderwrack.
This seaweed is found on the coasts of the North Sea, the western Baltic Sea, and the Atlantic and Pacific Oceans. Bladderwrack was the original source of iodine, discovered in 1811, and was extensively used to treat goiter—a swelling of the thyroid gland related to iodine deficiency.
Its fronds grow up to 150 cm long, with prominent midribs and spherical air bladders. Today, it remains a valuable herbal remedy.
