Aspartame Safety Study Stirs Emotions

June 26, 2007 -- Researchers and a scientific watchdog group are calling on regulators to take a new look at the safety of aspartame following a new study concluding that the popular sweetener promotes cancer in rats.

The study, published in a U.S. government journal, found increased rates of malignancies in animals fed aspartame throughout their lifespan. The product, which is the key ingredient in sweeteners including NutraSweet and Equal, is also used to sweeten thousands of food products and is widely used in diet soft drinks.

Aspartame first gained U.S. approval in 1981. Ever since, manufacturers have vigorously defended its safety. On Tuesday, an industry group blasted the study as flawed and warned it would needlessly alarm consumers.

But the Italy-based research team said their study shows that lifetime exposure of rats to aspartame -- beginning in the womb -- increased the incidence of having cancerous tumors by the time they died.

"We believe that a review of the current regulations governing the use of aspartame cannot be delayed," wrote researchers from the European Ramazzini Foundation of Oncology and Environmental Sciences in Bologna.  The study was published online in the journal Environmental Health Perspectives, published by the National Institute of Environmental Health Sciences.

The consumer group Center for Science in the Public Interest followed the study with a call on the FDA to revisit its original approval of aspartame.

"Because aspartame is so widely consumed, it is urgent that the FDA evaluate whether aspartame still poses a 'reasonable certainty of no harm,' the standard used for gauging the safety of food additives," Michael Jacobson, the group's executive director, said in a statement.

"But consumers, particularly parents, shouldn't wait for the FDA to act. People shouldn't panic, but they should stop buying beverages and foods containing aspartame," he said.

Previous Study 'Reassuring'

A study published last year by the National Cancer Institute found no correlation between aspartame consumption and cancer growth in nearly 475,000 people. While the study was not designed to find a causal link between aspartame and cancer, Jacobson's group at the time said they were reassured that aspartame is safe for humans at typical amounts most people consume.

On Tuesday, Jacobson said that sense of reassurance was gone thanks to the latest Italian animal study.

"The previous study was reassuring but certainly not definitive," Jacobson tells WebMD. "I think the FDA needs to take a new look at this, and then we'll go from there."

Beth Hubrich, a spokeswoman for the industry group Calorie Control Council, criticizes the study's methods.

"This goes against the overwhelming scientific literature that aspartame is safe," she tells WebMD.

That was echoed by the FDA. Spokesman Michael Herndon says the agency was interested in reviewing the Italian study. But he says the results are "not consistent" with results from a large number of other studies evaluated by the agency.

"Therefore, at this time, FDA finds no reason to alter its previous conclusion that aspartame is safe as a general purpose sweetener in food," the statement says.

Jacobson argues that most of those studies left "question marks" because they were industry funded.