What is Carrageenan ?

Carrageenan

Found in: Dairy products, non-dairy alternatives (coconut milk, rice milk, soy milk, etc.), processed lunch meats, and some supplements
What does it do? It’s a thickener, and especially used to replace fat.
Is it safe? Probably not.
Just from rat studies, you might think there’s nothing to worry about. The WHO has established an Acceptable Daily Intake of carrageenan as 0-75 mg/kg bw. Average daily intake is approximately 250mg/person/day, which falls well toward the low end of the “safe” spectrum.  In order to show any risk to humans, the studies supposedly showing a high risk would have to approximate this level. The animal studies linking carrageenan to intestinal inflammation and leaky gut don’t pass this sniff test. For example, in rats, an administration of either 9,690 mg/kg bw or 3876 mg/kg bw made colon tumors worse: no kidding! This paper  gives a useful overview of the problems with the rodent studies. But that doesn’t mean the stuff is good for you.
In human studies, some evidence shows that carrageenan increases intestinal permeability.  A study on isolated human intestinal cells found that carrageenan was inflammatory, and suggested it as a factor in the development of inflammatory bowel disease. In another study on isolated intestinal tissue, researchers found that carrageenan had a significant effect on the cells, although they didn’t link it to any specific disease.
Studies in real live humans would be better, but since these are obviously out for reasons of medical ethics, isolated human tissue is a lot more convincing as an experimental subject than rats. It’s probably safest to avoid carrageenan, at least until we have more research.