Fucoidan is a sulfated polysaccharide (MW: average 20,000) found mainly in various species of brown seaweed such as kombu, wakame, mozuku, and hijiki (variant forms of fucoidan have also been found in animal species, including the sea cucumber). Substantial pharmaceutical research has been done on fucoidan, focusing primarily on two distinct forms: F-fucoidan, which is >95% composed of sulfated esters of fucose, and U-fucoidan, which is approximately 20% glucuronic acid. As a consequence of this research, U-fucoidan is now being marketed as a nutraceutical, a "miracle drug", and a food supplement .