Carrageenan is made up of sodium, potassium, magnesium and calcium sulfate esters of galactose and 3,6-anhydrogalactose units. It is a wholly natural ingredient obtained from certain species of the red seaweed, class Rhodophyceae. Popular sources for carrageenan are the Chondrus crispus, Eucheuma cottonii and Eucheuma spinosum species.