Carrageenan is a common food additive that comes from red seaweed also known as Irish Moss or Chondrus Crispus. Carrageen has long been used as a thickener and emulsifier in ice cream, yogurt, cottage cheese and other processed food products, including soy milk.

Concerns about carrageenan have centered on the “degraded” type which is distinguished from the “undegraded” type by its lower molecular weight. Most of the studies linking carrageenan to cancer and other gastrointestinal disorders have focused on degraded carrageenan. But Dr. Tobacman thinks that undegraded carrageenan – the kind most widely used as a food additive – might also be associated with malignancies and other stomach problems. She suggests that such factors as bacterial action, stomach acid and food preparation may transform undegraded carrageenan into the more dangerous degraded type. Dr. Tobacman’s findings were published in the October 2001 issue of Environmental Health Perspectives, a publication of the National Institute for Environmental Health Sciences (NIEHS), a branch of the National Institutes of Health. So far, no government action has been taken as a result of Dr. Tobacman’s findings. She is currently looking into the possibility of an association between carrageenan and breast cancer risk.