Printer Friendly

Townsend's New York Observer: Carrageenan: pervasive food a that causes cancer, wipes out macrophages, and suppresses interferon.

If you're not the sort of person who scrutinizes the label of everything you buy, especially foods, then "quite likely you have swallowed carrageenan in more than one product over the past day." (I'm quoting from my column, Townsend Letter, June 2011.) Patented in the US in the 1930s for use as a food additive, carrageenan is label-listed as an ingredient in a multitude of products currently available on the shelves of American grocery and drug stores.


To cite a major example: carrageenan is used at low concentrations to prevent fractionation of milk components. Chocolate milk (carrageenan maintains chocolate in suspension), soy milk, other flavored milks, and nutritional supplement drinks (such as Ensure or Slim-Fast) include carrageenan for uniform consistency. Not all such products, of course, contain carrageenan. Some brands substitute other substances to maintain consistency. But carrageenan is usually cheaper than substitutes, which leads profit-hungry manufacturers to go with it.

Principally a food additive, carrageenan is often combined with other gums, such as locust bean gum, to improve the texture of foods. Well beyond foods, it is used in cosmetics, pharmaceuticals, pesticides, room deodorizers, and toothpaste. It is used, too, as an emulsifier in mineral oil laxatives, liquid petroleum, and cod liver oil. And even to treat ulcers!

Carrageenan's ability to substitute for fat and its ability to combine with milk proteins to increase solubility and texture partly explain its utilization in an extensive variety of food. (Toss in comparative cheapness as another important part of the explanation.) Hence, the addition of carrageenan in cottage cheese, ice cream, infant formula, low-calorie formulations of dietetic beverages, processed low-fat meats, whipped cream, and yogurt. (Great Britain and a few other European countries keep infant formula carrageenan free. The US allows it.) Again, not all manufacturers of these products add carrageenan for these reasons, but many do.

Based on data obtained from a 1977 survey of industry on the use of food additives, it was estimated that daily carrageenan intake for individuals older than 2 years was 100 mg. A 1971 survey of industry indicated that formula-fed infants in the first 5 months of life had an intake of 108 mg/daily.


Carrageenan has long been extracted from Chondrus crispus (commonly named "Irish moss"), a species of red algae abundant along the rocky parts of the Atlantic coasts of Europe and North America. In fresh condition, the plant is cartilaginous and soft, varying in color from greenish-yellow, through red, to dark purple or purplish-brown. The chief constituent of Irish moss (about 55%) is a mucilaginous body, a polysaccharide. The dried plant also consists of nearly 10% protein, about 15% mineral matter, and is high in iodine and sulfur.

Actually, Irish moss contains many vitamins and trace minerals, including beta-carotene, bromine, calcium, iron, magnesium, manganese, phosphorus, potassium, selenium and zinc; it contains pectin, B vitamins, and vitamin C as well.

The name carrageen for this species was introduced around 1829, possibly after a town with a similar name in Ireland. For over 200 years, it has been an ingredient in Irish home cooking, particularly as a thickener in puddings and desserts.

Because it has demulcent properties, Irish moss has been used as a home remedy, especially for respiratory ailments; a popular health periodical dated 1831 described it as such. Today, the website avows that traditionally, "the primary role of the herb was in speeding recuperation from debilitating illness, especially T.B. and pneumonia."

Antiviral and antibacterial properties found in Irish moss may make extracts of it beneficial during recuperation. A search on the Internet provided a smattering of articles in peer-reviewed journals that tend to support claims about New York Observer carrageenan's antiviral and antimicrobial activity. (The Internet provides a larger number of studies showing that when carrageenan is given to animals, it attacks macrophages and thereby undermines the body's immune system. Significant increases in viral and bacterial infections, with high death rates, result in these animals. For a fuller explanation of this deleterious activity, see "Findings of Harmful Effects," below.)

It is believed that Irish migrants escaping from the potato famines of the 18th and 19th centuries spread the use of carrageenan to New England in the US, where a modest processing industry later developed. This industry expanded enormously during World War II, mainly to replace agar, a gelatinous substance derived from the cell walls of certain red algae, which is used as a vegetarian substitute for gelatin. (Japan had been the chief supplier of agar from Pacific Ocean regions.) After World War II, carrageenan grew into a predominant additive in the food industry worldwide. Today, it is the foremost seaweed extract in the world's markets. The main producers of refined carrageenan are the US, France, Denmark, and the Philippines. Presently, the major source of "raw" carrageenan is tropical seaweeds of the genera Kappaphycus and Eucheuma.

Circumstances Accounting for Extensive Use In Humans

The US Food and Drug Administration gave GRAS status (Generally Regarded as Safe) to carrageenan in 1959. (GRAS substances may be incorporated into food products as long as good manufacturing processes are observed.)

The FDA proposed an amendment to the Code of Federal Regulations for carrageenan in 1972 to lessen public exposure to degraded carrageenan (which has low molecular weight fractions and causes harm). But the actual regulation was not amended, although several publications indicated that it had been modified. It was anticipated that a new rule-making proposal, which would comprehensively address all food safety aspects of carrageenan and its salts, would be made by the FDA in a year or two.

In 1982, the International Agency for Research on Cancer (IARC) stated that there was sufficient evidence for the carcinogenicity of carrageenan in animals to infer that "in the absence of adequate data on humans, it is reasonable, for practical purposes, to regard chemicals for which there is sufficient evidence of carcinogenicity in animals as if they presented a carcinogenic risk to humans." The US National Research Council (NRC) echoed IARC's designation for degraded carrageenan in a NRC monograph in 1996.

American and European researchers, institutionally funded rather than by the food industry, have expressed concerns about the use of undegraded carrageenan in food products over almost 40 years of separate investigations, yet no regulation limiting incorporation of carrageenan with low molecular weight fractions into food has been enacted in the US to date. The FDA undertook studies some two decades ago but has not substantively reviewed carrageenan since - despite increased evidence of the cancer-promoting activity of undegraded carrageenan and additional confirmation of its carcinogenic potential.

The Joint Expert Committee on Food Additives (JECFA), empanelled by the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) - both agencies of the United Nations - reevaluated the safety of carrageenan in 2007. JECFA noted that, "the previous dietary exposure estimate for carrageenan ... may be outdated. The Committee therefore recommended that a new dietary exposure evaluation, employing specific food type and use level information, be undertaken, ensuring that new uses are adequately taken into consideration." At this meeting, held in Geneva, Switzerland, JECFA chose not to specify an Acceptable Daily Intake (ADI) for carrageenan consumption in adults. The committee did make an exception for infant formula; in this case, "the Committee was of the view that based on the information available, it is inadvisable to use carrageenan or processed eucheuma seaweed in infant formulas." (See the "Conclusion" here for reasons.)

Findings of Harmful Effects

Joanne K. Tobacman, MD, published a definitive article about the harmful effects of carrageenan in 2001. (1) At the time, Dr. Tobacman was in the Department of Internal Medicine at the University of Iowa. That paper reviewed more than 40 studies that found intestinal ulcers and cancer in animals given carrageenan.

Dr. Tobacman, who has investigated the dangers of carrageenan consumption for well over a decade, characterizes carrageenan as a "wolf in sheep's clothing." She has published dozens of articles about it, has called for the food industry to avoid using it in their products, and urged consumers to avoid ingesting it.

In 2006, with three of her colleagues, Dr. Tobacman published results showing "that exposure of human intestinal epithelial cells to carrageenan triggers a distinct inflammatory pathway." She and her coinvestigators also observed that "exposure to undegraded as well as to degraded carrageenan was associated with the occurrence of intestinal ulcerations and neoplasms. (2) Further, Dr. Tobacman believes that carrageenan should be evaluated as a possible trigger in the development of breast cancer.

By providing evidence of carrageenan-induced damage to human intestinal epithelial cells, Dr. Tobacman's team may bring keener attention to carrageenan as a health hazard. (Inflammatory bowel disease is a recognized risk factor for colon cancer).

While Dr. Tobacman has concentrated mostly on the gastrointestinal effects of carrageenan in animals, other researchers have advanced previous investigations of carrageenan's effects on immunity. (3) Their findings have confirmed a generally known dark side of carrageenan; that it is cytotoxic to macrophages. (Immune cells found all over the body, macrophages act as scavengers that digest invading infectious bacteria and viruses, engulf and eat dead and malfunctioning body cells, and ingest other foreign particles and debris.)

Back in 1986, researchers found that carrageenan suppresses the production of interferon gamma. (4) Gamma interferon, also known as type II interferon, is a cytokine crucial for innate and adaptive immunity against viral and intracellular bacterial infections and for tumor control. Abnormal gamma interferon expression is associated with a number of autoinflammatory and autoimmune diseases. The importance of gamma interferon in the immune system is due in part to its ability to inhibit viral replication directly, and most importantly from its stimulatory and modulating effects in the body's immune defense.


In an article published in Medical Hypotheses in 2001, Dr. Tobacman and her coauthors hypothesized that "low molecular weight carrageenan may contaminate food-grade carrageenan, and acid-hydrolysis leads to shortening of the carrageenan polymer to the degraded form, poligeenan. It is not unreasonable to speculate that normal gastric acid and acid contained in foods co-ingested with carrageenan may act upon ingested carrageenan and convert some of what is ingested to the lower molecular weight poligeenan during the actual process of digestion."

That article also hypothesized that "some intestinal bacteria possess the enzyme carrageenase that degrades carrageenan. Hence, it is possible that humans, either by endogenous acid secretion, by co-consumption of acid foods, or by the action of intestinal flora, may degrade carrageenan into the lower molecular weight poligeenan."

Regarding poligeenan, it is necessary to understand that "poligeenan is produced from carrageenan subjected to high temperatures and acidity. The average carrageenan molecule weighs over 100,000 Da [daltons] while poligeenans have a molecular weight of less than 50,000 Da. A scientific committee working on behalf of a European commission has recommended that the amount of degraded carrageenan be limited to a maximum of 5% (which is the limit of detection) of total carrageenan mass. (5)

Keep in mind as well that there are two types of carrageenan, undegraded (food-grade) and degraded (hydrolyzed with acid). Undegraded carrageenan has been added to foods in massive amounts around the world since the 1930s. In the US, the FDA has assured its safety. Chemically treated, degraded carrageenan is a known carcinogen and is not permitted in food. (It is frequently used to induce intestinal inflammation in animals experimentally.)

Mounting evidence of adverse effects, several unanswered questions, and unaddressed concerns hang over the safety of carrageenan. I'd shun foods and nonfood products that add it, where that's possible. Many, perhaps most, Americans (myself included frequently) don't diligently, fastidiously check the ingredients listed on all the foods and other products that they buy. This is why the first sentence of this column reads in part: "quite likely you have swallowed carrageenan in more than one product over the past day."

I promised a rationale for excluding carrageenan from infant formula. Best I could come up with: carrageenan has no nutritional value, and studies have demonstrated that it poses health risks. For instance, it cannot be excluded that carrageenan might be absorbed by the immature gastrointestinal tract and that the absorbed material might affect the immune system of an infant.

Additionally, it's reasonable to presume that infant formula should only include ingredients in amounts that have nutritional or other benefits. Unnecessary ingredients, or unnecessary amounts of them, may burden metabolic and other physiologic functions of an infant.


(1.) Tobacman JK et al. Review of harmful gastrointestinal effects of carrageenan in animal studies. Environmental Health Perspectives. October 2001;109(10).

(2.) Tobacman JK et al. Carrageenan induces interleukin-8 production through distinct Bc110 pathway in normal human colonic epithelial cells. Am J Physiol. November 9, 2006;292:G829.

(3.) See, for example, Thomson AW et al. Immunopharmacology of the macrophage-toxic agent carrageenan. Int J Immuno Pharmac. 1979;1:247-261; and Tomioka H et al. Comparative roles of macrophages and NK cells in the host resistance of mice to mycobacterium fortuitum infection. J Infect. 2004;48:74-80. In the 2004 study, the investigators observed that three out of four infected mice given carrageenan died of the infection.

(4.) Suzuki F et al. Suppression of interferon gamma production in mice treated with carrageenan. Eur J Immunol. 1986 Apri1;16(4):375-380.

(5.) Carrageenan [Web article]. Wikipedia. wikipedia/en/wiki/Carrageenan.

by Marcus A. Cohen

Marcus A. Cohen's "baptism" in the whirlpools of medical politics dates to 1984, when he served as government and media liaison for patients under alternative cancer therapy. Subsequently, he has advocated broadening plausible treatment options for patients unresponsive to conventional care. A Townsend Letter columnist since 2004, he has reported and commented on a wide range of health-care topics; he is also the author of a paperback, Lyme Disease Update, published by the Lyme Disease Association in 2004.
COPYRIGHT 2011 The Townsend Letter Group
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2011 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Author:Cohen, Marcus A.
Publication:Townsend Letter
Article Type:Report
Geographic Code:1USA
Date:Jul 1, 2011
Previous Article:Nutrition Textbook Offers Deep Insight.
Next Article:Integrative Medicine perspective by Dr. Julie: are you spending money putting toxins in your body?

Terms of use | Privacy policy | Copyright © 2018 Farlex, Inc. | Feedback | For webmasters