Not so sweet: cancers in rats that consumed aspartame.
A large, new test in rats suggests that the artificial sweetener aspartame aspartame: see sweetener, artificial.
Synthetic organic compound (a dipeptide) of phenylalanine and aspartic acid. It is 150–200 times as sweet as cane sugar and is used as a nonnutritive tabletop sweetener and in low-calorie may be a carcinogen carcinogen: see cancer.
Agent that can cause cancer. Exposure to one or more carcinogens, including certain chemicals, radiation, and certain viruses, can initiate cancer under conditions not completely understood. . But scientists not affiliated with the research express doubts about the study's validity and point to earlier trials that produced the opposite result.
Aspartame, sold under the brand names Equal and NutraSweet, is used in thousands of products, including diet soft drinks and sugarfree gum. The acceptable daily intake acceptable daily intake
the amount of a drug or chemical residue to which an animal can be exposed daily for a lifetime without suffering a deleterious or injurious effect, on the basis of all of the facts known at the time. set by the Food and Drug Administration is 50 milligrams per kilogram body weight (mg/kg) per day, the equivalent of about 20 cans of diet soda.
Eight past studies looked at whether the sweetener causes cancer in lab animals, says veterinary pathologist James Swenberg of the University of North Carolina at Chapel Hill The University of North Carolina at Chapel Hill is a public, coeducational, research university located in Chapel Hill, North Carolina, United States. Also known as The University of North Carolina, Carolina, North Carolina, or simply UNC . "There's one equivocal study, and the rest are clearly negative for this endpoint [cancer]," he says.
But medical oncologist Morando Soffritti says that the earlier trials were small, funded by aspartame's manufacturer, or never published in detail in the scientific literature. Soffritti led the new study, which appears in the March Environmental-Health Perspectives. He works at a nonprofit organization, the European Ramazzini Foundation of Oncology and Environmental Sciences in Bologna, Italy.
Soffritti and his colleagues examined 1,800 rats, making their study larger than the past aspartame-carcinogenicity tests. The researchers divided the animals into seven groups and gave each group drinking water with either no aspartame or a daily dose of aspartame between 4 mg/kg and 5,000 mg/kg.
The experiment continued until the animals died, which took an average of 2 years. Pathologists dissected each animal to detect any cancers.
The researchers found more cancers, particularly more lymphomas and leukemias, in animals exposed to aspartame than in unexposed animals. The number of cancers detected increased in proportion to the amount of the sweetener that the animal had ingested, the team reports.
That dose-response relationship is a strong sign that aspartame causes cancer, Soffritti says. "We have shown that aspartame is a carcinogenic agent," he concludes.
Because the study is so large and includes a wide range of doses, it has "a fair amount of power," says toxicologist John Bucher of the National Toxicology Program National Toxicology Program Environment A program that conducts toxicologic tests on substances frequently found at the EPA's National Priorities List sites, which have the greatest potential for human exposure in Research Triangle Park Research Triangle Park, research, business, medical, and educational complex situated in central North Carolina. It has an area of 6,900 acres (2,795 hectares) and is 8 × 2 mi (13 × 3 km) in size. Named for the triangle formed by Duke Univ. , N.C. The study might detect a subtle carcinogenic effect that had been invisible in previous, smaller studies, he says.
However, the relationship between aspartame dose and cancer incidence reported by the Ramazzini researchers was "not overly strong," Bucher adds. "It's not like [what] one would get with a frank, strong carcinogen."
Lois Swirsky Gold, who directs the Carcinogenic Potency Database at the University of California, Berkeley The University of California, Berkeley is a public research university located in Berkeley, California, United States. Commonly referred to as UC Berkeley, Berkeley and Cal , says that she isn't convinced that the data reflect an increase in tumors with dose.
Furthermore, says Swenberg, the Ramazzini researchers bucked the convention that laboratory animals be sacrificed at a predetermined pre·de·ter·mine
v. pre·de·ter·mined, pre·de·ter·min·ing, pre·de·ter·mines
1. To determine, decide, or establish in advance: point to ensure that their tissues get preserved immediately upon death. The team presumably pre·sum·a·ble
That can be presumed or taken for granted; reasonable as a supposition: presumable causes of the disaster. ended up with less-than-well-preserved tissues, in which identification of cancers would be difficult, he says.
He and Gold both recommend that an independent group of pathologists reevaluate the tissues identified as tumors.
The FDA FDA
Food and Drug Administration
n.pr See Food and Drug Administration.
n.pr the abbreviation for the Food and Drug Administration. says that it has requested that the Ramazzini researchers share all their raw data.
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