Methods of purification process of fucoidan from seaweed extracts

A method of purifying fucoidan a heterogeneous mixture, the method comprising: (a) providing a source of fucoidan; (B) removing heavy metal ions from said source treating with a chelating agent to produce a first mixture of fucoidan; (C) selectively precipitating this fucoidan in said fucoidan first mixture to remove contaminants; (D) resuspending the precipitate containing fucoidan in aqueous solution to produce a second mixture of fucoidan; (E) repeating steps (c) and (d) one or more times; and (f) filtering the aqueous solution comprising fucoidan to remove bacterial contaminants and endotoxin purified to give fucoidan.