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Safety of carrageenan in foods.

Environmental Health Perspectives
Environmental Health Perspectives
Publication Date
  • Letter
  • Biology
  • Medicine
  • Pharmacology


110(4) FrontPages Safety of Carrageenan in Foods A recent review of the toxicology of car- rageenan by Tobacman (1) raised questions about the safety of carageenan-containing foods. Intact carageenan is a high molecular weight hydrocolloid (molecular weight 1.5–20 × 106). One concern has focused on the potential for degraded (low molecu- lar weight) carageenan to be formed by acid hydrolysis in the stomach and the possibili- ty that this material could promote cancer of the colon (1). Rats fed degraded car- rageenan have been shown to develop col- orectal tumors (2). Studies involving initia- tion with the genotoxic carcinogen azoxymethane, followed by quantitation of the number of aberrant intestinal crypts formed in response to subsequent car- rageenan exposure, have also suggested that degraded carageenan has the potential to promote colon cancer in rats (3). These findings have led to degraded carrageenan being classified by the International Agency for Research on Cancer (IARC) as 2B, a possible human carcinogen, based on animal study data. Native carrageenan has been classified by IARC as 3, unclassifiable with respect to carcinogenicity in humans. In a recent paper, Taché et al (4) used a well-established and highly sensitive aberrant crypt assay to examined the potential for carrageenan to promote azoxymethane-induced colonic cancer; they found no promoting effect when a humanized gut flora was used. Because the carrageenan was administered in the drink- ing water, it was available for degradation in the acidic environment of the stomach. The use of normal rodent microbiologic flora produced a promoting effect of car- rageenan in this model system (4), con- firming positive results of previous studies, in contrast with the negative effect that occurred using humanized intestinal flora in the rat. Thus, the conclusion must be that this colon cancer-promoting effect is a rodent-specific phenomenon, requiring a rodent intestinal microbiologic flora, and that carrageenan would not p

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