FRIDAY, Oct. 26, 2001 (HealthDayNews) -- Here's something else to add to that growing list of things to avoid -- carrageenan.
It's a common food additive, and one researcher says it may play a role in the development of colon cancer and inflammatory bowel diseases, like ulcerative colitis. Other experts, however, are not convinced that there is enough evidence to say that the substance poses a health risk to humans.
"Carrageenan is a wolf in sheep's clothing," says Dr. Joanne Tobacman, an assistant professor of clinical internal medicine at the University of Iowa in Iowa City. "It looks innocent, like a simple molecule, but it's really not metabolizable."
Carrageenan is a gum that comes from red seaweed plants. Used to thicken and improve the texture of foods, it can be found in many of them, including ice cream, yogurt, cottage cheese, condensed milk, pudding, jams, soy products and bakery products. It has been used in foods in the United States since the 1930s.
Tobacman reviewed 45 past experiments on animals and carrageenan for a study that appears in the current issue of Environmental Health Perspectives. She found that carrageenan caused intestinal problems in many animals, such as rabbits, rats, mice and guinea pigs. "I think we have very good evidence in many animal studies that [carrageenan] is clearly a cause of intestinal malignancies and ulcerations in animal models," says Tobacman. And, she believes it may pose a similar risk to humans.
A spokesman for the U.S. Food and Drug Administration (FDA) says there are two kinds of carrageenan -- undegraded and degraded. Undegraded carrageenan is what has been approved by the FDA for use in food. Degraded carrageenan has changed into a different substance and really isn't carrageenan anymore, says the spokesperson, and that is often what's been used in research studies.
According to the FDA, carrageenan is considered safe when manufactured according to FDA guidelines.
Tobacman, however, says that virtually all carrageenan changes into degraded carrageenan. She says even when manufacturers use undegraded carrageenan, food preparation and the acid in our stomachs inevitably break some of the substance down into degraded carrageenan.
Because of this, she believes the FDA should more strictly regulate the use of carrageenan, especially since other thickening agents, like locust bean, guar and xanthan, are available for food manufacturers to use.
While agreeing it would probably be a good idea for the FDA to review these studies, Ruth Kava, director of nutrition for the American Council on Science and Health, says the question of whether carrageenan could be harmful to humans is very much up in the air.
"An awful lot of these experiments didn't give the carrageenan in a way analogous to humans," says Kava. Researchers often gave the animals undegraded carrageenan in drinks and sometimes even infused the substance directly into the animals' intestines, she says. And, she adds, the results varied from species to species.
"In most animal models, carrageen has not been found to be a problem, except in guinea pigs," she adds. Carrageenan is a carcinogen for guinea pigs, according to the study.
Kava says this situation may be similar to the saccharin studies done many years ago. That food additive was banned when studies on rats found that high doses of saccharin caused cancer in rats. Later studies exonerated the sweetener.
But, she adds, this study dose raise some interesting questions that should probably be studied further.
What To Do
Tobacman says she tries to avoid carrageenan whenever she can. But it's not always listed on food labels. For example, condensed milk almost always contains carrageenan, so if a product label lists condensed milk as an ingredient, it probably contains carrageenan as well even if it isn't separately listed.
To learn more about how carrageenan works, go to HowStuffWorks.com.
For more information on food additives and how they're regulated, see this article from the U.S. Food and Drug Administration.
