Carrageenans or carrageenins are a family of linear sulfated polysaccharides that are extracted from red edible seaweeds. Though they have no nutritional value, they are widely used in the organic food industry for their gelling, thickening, and stabilizing properties.
Research has shown that exposure to undegraded carrageenan causes inflammation and has been linked with malignancies and other stomach problems.
Carageenan has been used by drug researchers to cause inflammation in tissues in order to test the anti-inflammatory properties of new drugs. When laboratory mice are exposed to low concentrations of carrageenan for 18 days, they develop “profound” glucose intolerance and impaired insulin action, both of which can lead to diabetes. Observed effects in rats include epithelial cell loss, increased intestinal permeability, and diarrhea. In guinea pigs, carrageenan at a 5% concentration in the diet caused ulcers in the colon. In pigs, concentrations of carrageenan resulted in abnormalities in the intestinal lining, but no ulcerations or tumors.