Rating: Caution

Thickening, gelling, and stabilizing agent: Dairy and non-dairy products, including ice cream, sorbet, frozen desserts, chocolate milk, soy milk, almond milk, yogurt, cottage cheese, whipping cream; jelly, infant formula, salad dressings, deli meat, frozen dinners.

Carrageenan is a family of indigestible large molecules obtained from certain seaweeds. It is used as a thickening or texturing agent in a wide variety of foods and beverages.

Large amounts of carrageenan have harmed test animals' colons. The amounts in food are too small to be a concern for most people, but an independent committee of the World Health Organization (WHO) concluded that it is unclear whether people with episodes of gastrointestinal disease might absorb some carrageenan, which presumably could cause gastrointestinal or immune system problems. Some people have reported that eliminating carrageenan from their diet diminished or eliminated their gastrointestinal discomfort.

Carrageenan—at least in its natural, undegraded form—does not cause cancer in animals. In animal studies, high doses of carrageenan increase the potency of chemicals that cause cancer, and there has been controversy over whether it could do so at the low levels that people consume. The FDA and the WHO committee have concluded that food-grade carrageenan does not pose either a direct or an indirect cancer risk.

Food-grade carrageenan contains small amounts of “degraded” carrageenan, and a bit more probably forms in the acidic conditions of the stomach. The International Agency for Research on Cancer, another unit of the WHO, considers degraded carrageenan to be “possibly carcinogenic in humans.” While any possible cancer risk would be quite small, some people may wish to err on the side of caution and avoid carrageenan.

Some experts have been concerned about the safety of carrageenan for infants, given that the GI tract of the infant is still developing. In 2014, however, the WHO committee reviewed new animal studies and concluded that infant formula made with carrageenan is safe.