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Does Cyclamate Cause Cancer?

The idea that cyclamate may cause cancer rests on one study: When scientists fed 80 rats a cyclamate/saccharin mixture at a level equal to 5% of their diets, 12 of them developed bladder cancer within two years. Since then, there have been more than two dozen studies in which animals were fed similar levels of cyclamate for their entire lives; none has given any indication that the sweetener causes cancer.

As a result, the Cancer Assessment Committee of the FDA's Center for Food Safety and Applied Nutrition concluded in 1984 that, "the collective weight of the many experiments... indicates that cyclamate is not carcinogenic (not cancer causing)." The results of the 1969 study that led to banning of cyclamate, the committee says, "are... not repeatable and not explicable." The following year, the National Academy of Sciences added that, "the totality of the evidence from studies in animals does not indicate that cyclamate... is carcinogenic by itself." A joint committee of the World Health Organization (WHO) and the Food and Agriculture Organization (FAO) has similarly concluded that cyclamate is safe for human consumption. Unlike the two United States groups, the WHO/FAO panel addressed issues of genetic damage as well as cancer.

One of the most peculiar aspects of the entire regulatory situation is that, although the apparently incriminating study used a mixture of cyclamate and saccharin, only cyclamate was banned. We now know-although we did not in 1969—that saccharin itself produces occasional bladder cancers. So if the rats' diets did indeed cause their cancers (which some scientists doubt), most people today would assume that the saccharin was at fault.

Despite strong evidence for cyclamate's safety—the WHO/FAO committee commented, "one wonders how may common foodstuffs would be found on such testing to be as safe as that"—future United States use of the sweetener remains uncertain on both regulatory and economic grounds. Nevertheless, many people hope that the FDA will soon clear this 25-year-old case from its docket. Whether manufacture of cyclamate will then resume remains to be seen.



Klaassen, Curtis D. Casarett and Doull's Toxicology. 6th ed. Columbus: McGraw-Hill, Inc., 2001.


Lecos, Chris W. "Sweetness Minus Calories = Controversy." FDA Consumer (February 1985): 18.23.

W. A. Thomasson

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