Washington, August 28, 2008 - Coca-Cola and Pepsi are planning to introduce new drinks made with rebiana, an extract of stevia leaves that is 200 times sweeter than sugar. But according to a new 26-page report by toxicologists at the University of California, Los Angeles, several, though not all, laboratory tests show that the sweetener causes mutations and DNA damage, which raises the prospect that it causes cancer. In a letter to the Food and Drug Administration, the Center for Science in the Public Interest says the agency should require additional tests, including a key animal study, before accepting rebiana as Generally Regarded as Safe, or GRAS.
"A safe, natural, high-potency sweetener would be a welcome addition to the food supply," said CSPI executive director Michael F. Jacobson. "But the FDA needs to be as sure as possible that rebiana is safe before allowing it into foods that would be consumed by tens of millions of people. It would be tragic if the sweetener turned out to cause cancer or other problems."
One key animal study has not been conducted, according to the UCLA experts and CSPI. The FDA's guidelines advise testing prospective major new food additives on two rodent species, usually rats and mice. The new sweetener has only been tested on rats, but not mice. The toxicologists' report said that because several studies found mutations and DNA damage, a lifetime mouse study designed to evaluate the risk of carcinogenicity and other health problems was particularly important.
The new report was prepared for CSPI by Sarah Kobylewski, a graduate student in the Department of Molecular Toxicology, and Curtis D. Eckhert, Ph.D., a professor of Environmental Health Sciences and Molecular Toxicology, at UCLA. They were assisted by Professor Joseph R. Landolph, Jr., Ph.D., of the Department of Molecular Microbiology and Immunology, and Pathology, Keck School of Medicine, and the School of Pharmacy at the University of Southern California.
The UCLA toxicologists emphasized the need for more genotoxicity tests, because of the evidence that derivatives of stevia that are closely related to rebiana damage DNA and chromosomes. Their report noted that much of the recent research on rebiana was sponsored by Cargill and urged the FDA to obtain independently conducted tests to ensure that corporate biases don't influence the design, conduct, or results of the tests.
Rebiana is shorthand for rebaudioside A, a component of stevia. It is obtained from the leaves of a shrub native to Brazil and Paraguay. Coke, Pepsi, and other companies are excited about rebiana, because it supposedly tastes better than crude stevia, which is sold as a dietary supplement in health-food stores. After all the controversies pertaining to saccharin, aspartame, and other artificial sweeteners, the food industry expects many calorie-conscious consumers to eagerly opt for this natural sweetener.
Two companies—Cargill and Merisant—have told the FDA that rebiana should be considered GRAS, a category given less scrutiny by the FDA than ordinary food additives. A third company, Wisdom Natural Brands, has declared that its stevia-based sweetener is GRAS and will market it without giving evidence to, or even notifying, the FDA. That company gave CSPI only a heavily redacted report prepared by scientists it hired to declare its stevia derivative, which is of unknown purity, is safe.
Stevia is legal in foods in Japan and several other countries, but the United States, Canada, and the European Union bar stevia in foods because of older tests that suggested it might interfere with reproduction. New tests sponsored by Cargill did not find such problems.
"I am not saying that rebiana is harmful, but it should not be marketed until new studies establish that it is safe," Jacobson said.
Cargill's version of rebiana is called Truvia and would be used by Coca-Cola. Pepsi’s version is called PureVia and is produced by Merisant’s Whole Earth Sweetener division. Merisant is best known for marketing the Equal brand of aspartame.
CSPI has not questioned the safety of two artificial sweeteners, sucralose (Splenda) and neotame, but says that suggestive evidence indicates that saccharin, aspartame (Equal, NutraSweet), and acesulfame-K pose small risks of cancer.
"The whole issue of what gets GRAS status needs to be reviewed by Congress," Jacobson said. "It’s crazy that companies can just hire a few consultants to bless their new ingredients and rush them to market without any opportunity for the FDA and the public to review all the safety evidence."
Two of the most harmful ingredients in the food supply are considered GRAS: salt which raises blood pressure and causes thousands of unnecessary heart attacks and strokes every year, and partially hydrogenated oil, which is the source of artery-clogging artificial trans fat. CSPI has long campaigned to get partially hydrogenated oil out of the food supply and to reduce salt to safe levels.