Study reignites debate on sweetener's safety

Researchers have strengthened a link between aspartame - a common sweetener in diet sodas, medicines and sugar-free candies - and cancer in rats.
The chemical is sold under the brand name NutraSweet.

The study, conducted by a team of Italian scientists, demonstrates that aspartame is particularly potent when animals are exposed in utero and during development. The rats were exposed to the sweetener at levels above and below the recommended daily maximums for people.

The research was published online this month in Environmental Health Perspectives, a U.S. government sponsored, peer-reviewed journal.

This study raises "serious questions about the safety of the artificial sweetener aspartame," said Mike Jacobson, executive director for the Center for Science in the Public Interest, a public health watchdog group based in Washington, D.C.

He is hoping the Food and Drug Administration will take notice and re-evaluate the artificial sweetener.

But the Calorie Control Council, an industry group, disagrees. Beth Hubrich, a registered dietitian for the council, said the methodology was faulty, and she expressed concern that the study would unnecessarily alarm people.

"It is difficult to understand why the National Institute of Environmental Health Safety would publish such studies in Environmental Health Perspectives when the design and execution did not follow guidelines set up by the National Toxicology Program," Ms. Hubrich wrote in an e-mail.

The study, from the European Ramazzini Foundation of Oncology and Environmental Sciences - an independent, non-profit foundation based in Bologna, Italy - indicated that cancers, including lymphomas, leukemias and breast cancer, were more common in rats exposed to the sweetener than in animals that were not exposed. And there was dose-related response.

"On the basis of our scientific data, we believe that aspartame should be avoided as much as possible, especially by pregnant women and children," Morando Soffritti, the lead researcher on the study, wrote in an e-mail.

The acceptable daily intake of aspartame is 50 milligrams per kilogram of body weight in the United States, and 40 milligrams per kilogram of body weight in the European Union.

That's a lot of aspartame. For a 150-pound U.S. adult, that's about 18 cans of diet soda each day. For a 50-pound child, it's closer to six cans a day.

But aspartame isn't just in diet sodas. It is also in yogurts, sugar-free desserts, gums and medicines. Therefore, it is likely that one's daily aspartame consumption is often underestimated, according to Mr. Soffritti.

To investigate the effects of the sweetener on rats, Mr. Soffritti and his team separated pregnant females into three groups. One group was given feed with a high dose of aspartame (100 mg/kg body weight), another group was fed a lower dose (20 mg/kg body weight) and the third group had no sweetener.

Feeding was initiated on the 12th day of pregnancy.

The mother rats were killed after weaning their pups, and their offspring were allowed to live until they died of natural causes. The offspring got the same feed as their mothers.

In all, 400 rats were examined in this study.

When the offspring died, they were examined for cancer and disease. The researchers looked at their skin, fat, mammary glands, brains, pituitary glands and salivary glands.

The Italian team discovered a statistically significant dose-related increase of malignant tumors in rats who were fed the artificial sweetener. The high-dose group showed statistically significant increases in tumors - as much as 15 percentage points higher in males - while the low-dose group showed non-significant increases in lymphomas and leukemias in both sexes, and breast cancers in females.

The results, Mr. Soffritti said, "call for urgent reconsideration of regulations governing the use of aspartame as an artificial sweetener."

"This is not just an opinion," he said, "but in the United States, it is also the law."

The Delaney Clause of the Food Additives Amendment of 1958 mandates that any food additive shown to cause cancer in people or in laboratory animals - as demonstrated in rigorous safety tests - should be considered unsafe by the Food and Drug Administration.