Rat Study Shows Cancer, Aspartame Link
But Critics Charge That Research Is Flawed
Nov. 18, 2005 - A study in rats links the popular artificial sweetener aspartame to a wide range of cancers, but industry officials charge that the research is badly flawed.
Aspartame is found in the low-calorie sweetener Equal and in many other sugar-free products under the brand name NutraSweet. It is the second best-selling nonsugar sweetener in the world.
Researchers in Italy concluded that rats exposed to varying doses of aspartame throughout their lives developed leukemias, lymphomas, and several other cancers in a dose-dependent manner.
They report that the product is a potential cancer-causing agent to humans even at levels that are less than half of what is considered safe by the U.S. government.
The study appears in the Nov. 17 issue of the journal Environmental Health Perspectives, which is published by the National Institute of Environmental Health Sciences (NIEHS) of the U.S. Department of Health and Human Services.
But critics charged that the investigators did not follow the guidelines for scientific study outlined by the NIEHS' own research group, the National Toxicology Program. They further noted that the NTP's own animal studies involving similar levels of aspartame exposure showed no link between the sweetener and an increase in cancers.
And an NIEHS spokesperson said Friday that the agency had "no role in the design, performance, or interpretation" of the newly published study.
'Findings Speak for Themselves'
The study was conducted by researchers from the European Ramazzini Foundation, an independent group located in Bologna, Italy.
One hundred male rats and 100 female rats were followed from 8 weeks of age until their deaths from natural causes. The rats were fed aspartame at doses approximating a wide range of human consumption levels, from very low levels to very high.
Each rat was autopsied following its spontaneous death, and exposed animals were found to have a higher rate of leukemias, lymphomas, kidney and pelvic cancers and a brain cancer.
Researcher Morando Soffritti, MD, and colleagues called for an "urgent re-evaluation" of the current guidelines for the use of aspartame.
"The findings speak for themselves," he tells WebMD. "They show the potential carcinogenicity of aspartame in animals."