Carrageenan is extracted from the red algae seaweed Irish Moss (Chondrus crispus) pictured here...
The molecular formula of Carrageenan is (C12H18O9)n. The question of health and safety of Carrageenan is in the variable quantity 'n' at the end...
The issue with Carrageenan is that it promotes inflammation when it is broken down into low molecular weight components.
Degraded, low molecular weight Carrageenan has been used in research to trigger an inflammatory response. At a molecular weight of 10,000 to 20,000 Daltons, it is called Poligeenan. Safety concerns have been raised about Carrageenan with a molecular weight below 50,000 Daltons.
If Carrageenan is intact with a molecular weight of over 200,000 Daltons, it is fine for use in supplements and foods.
Since molecular weight of Carrageenan is not always specified on labels, you may need to contact the manufacturer to find out the molecular weight of the ingredient used.
We use Carrageenan as an ingredient in our vegetarian gel capsules for NeurOmega. We specify that the molecular weight is over 200,000 Daltons.
We prefer to use Carrageenan over Gelatin because of concerns that Gelatin may carry a risk of contamination with Glyphosate. Some doctors and researchers think that Glyphosate may substitute for Glycine in proteins.