relativelyquantum - carageenan is an extract taken from red seaweed. That's where it comes from. I just read an article the other day saying carageenan is completely harmless and completely natural...I can't find it though. It was talking about
a study that showed degraded carrageenan (poligeenan) may cause ulcers in the GI tract. That is different than the carageenan in food, which they found to be not harmful. After testing samples of foods containing carageenan, the researchers found no poligeenan. I'm not up-to-date with other possible studies on it though.
As I sit here and eat my carrageenan-filled yogurt, I found another study (from 2001) that says carrageenan may be a possible cause of IBD. It's a very long read... http://www.encyclopedia.com/doc/1G1-81760722.html