Aspartame, sold under the brand names NutraSweet and Equal and found in popular products like Diet Coke, Diet Pepsi, Diet Snapple and Sugar Free Kool-Aid, has been under pressure for the past two years from evidence that it might cause leukemia, lymphoma and breast cancer in rats. Reuters reports today that the FDA is “unmoved” by this evidence, which comes from Italy.

FDA spokesman Michael Herndon said the agency had not yet reviewed the study. This is a bit of a quibble, for the FDA posted a press release this April stating that they had considered the findings but, feeling a lack of due access to the study’s data, they reached no final conclusion, except so far as they believe aspartame is safe.

Dr. Morando Soffritti is the Scientific Director of the European Foundation for Oncology and Environmental Sciences. He and colleagues at the Ramazzini Foundation in Bologna, Italy conducted a seven-year study testing aspartame by feeding it to rats from 6-8 weeks of age until they died naturally. The scientists suspect that studies of 30 years ago, which led the FDA and other health watchdogs to declare aspartame to be safe, focused on animals younger than those in which cancer would likely be seen. The older studies killed and autopsied the animals about two-thirds through a normal rat’s life span, so could have missed any increase in age-related disease. In humans, they point out, “approximately 80% of cancer diagnoses are made in the last third of life, after age 55.”

In 2006, the Ramazzini Foundation announced that their study of more than 4,000 rats showed that a lifetime of eating doses of the sweetener raised the likelihood of several types of cancer. A follow-up study was designed to find out whether aspartame in maternal diet may kick-start adverse effects in offspring.

In an editorial accompanying the 2006 publication of the first study, M. Nathaniel Mead said:

The carcinogenic effects were evident at daily doses as low as 400 parts per million, equivalent to an assumed daily human intake of 20 milligrams per kilogram body weight (mg/kg). This dosage is much less than the acceptable daily intake for humans, with current limits set at 50 mg/kg in the United States and 40 mg/kg in Europe.

The cancer-causing doses in rats were higher than most people consumed a decade ago, when the product was relatively new. “Surveys of aspartame intake in the United States and Europe from 1984 to 1992 showed that consumers typically consumed 2–3 mg/kg daily,” Mead writes, “with small children and women of child-bearing age consuming slightly more, at 2–5 mg/kg daily.”

But 20 mg/kg is within the range of moderately heavy consumers of diet sodas and other artificially sweetened foods. “A 140-pound woman would need to drink just three cans of diet soda a day,” according to WebMD/CBS. “A 180-pound man would need to drink four cans of diet soda a day.”

And diet soda isn’t the only source of aspartame. The sweetener is in thousands of products, ranging from yogurt to over-the-counter medicines.

The average person consumes about 2 or 3 mg/kg aspartame each day. However, that figure goes way up for children and young women.

This past April, 2007 FDA issued a statement about its findings so far:

FDA could not conduct a complete and definitive review of the study because ERF did not provide the full study data. Based on the available data, however, we have identified significant shortcomings in the design, conduct, reporting, and interpretation of this study. FDA finds that the reliability and interpretation of the study outcome is compromised by these shortcomings and uncontrolled variables, such as the presence of infection in the test animals.

Additionally, the data that were provided to FDA do not appear to support the aspartame-related findings reported by ERF. Based on our review, pathological changes were incidental and appeared spontaneously in the study animals, and none of the histopathological changes reported appear to be related to treatment with aspartame. FDA believes that additional insight on the study findings could be provided by an internationally-sponsored pathology working group examination of appropriate tissue slides from the study.

Considering results from the large number of studies on aspartame’s safety, including five previously conducted negative chronic carcinogenicity studies, a recently reported large epidemiology study with negative associations between the use of aspartame and the occurrence of tumors, and negative findings from a series of three transgenic mouse assays, FDA finds no reason to alter its previous conclusion that aspartame is safe as a general purpose sweetener in food.

This week, Monday June 25, The Calorie Control Council, a trade group for the artificial sweetener and the low-calorie and reduced-fat food and beverage industries, threw its support behind the FDA and took aim not only at Dr. Soffritti’s studies but also at US toxicologists and medical science journals that have aired his findings.

The Council questions why scientists at federally-supported US science and health institutions and publications are breaking step on the aspartame issue. Calorie Council president Lyn Nabors said in a press-release: “It is unfortunate that some scientists associated with [The National Toxicology Program] NTP are lending credibility to the Ramazzini Institute and questioning the safety of aspartame, when government institutions such as the NTP, the National Cancer Institute, the FDA and others have found no relationship between aspartame and cancer.”

Further, Nabors said, “it is difficult to understand why Environmental Health Perspectives (EHP), a publication of the National Institute of Institutes of Environmental and Health Sciences (NIEHS) published the Ramazzini study, “when the design and execution did not follow guidelines set up by the NTP (the U.S. government toxicology initiative administered by NIEHS).”

Environmental Health Perspectives is an open-access journal, so the public is free to see what the fuss is about. Dr. Soffritti’s team wrote last year:

“On the basis of the present findings, we believe that a review of the current regulations governing the use of aspartame cannot be delayed,” Soffritti’s team wrote last year in the journal Environmental Health Perspectives, published by the U.S. National Institute of Environmental Health Sciences. “The mega-experiment performed in our laboratory on APM . . . has shown for the first time the multipotential carcinogenic effects of this compound.”

“The increase in lymphomas/leukemias in APM-treated females could be related to its metabolite methanol, which is in turn metabolized to formaldehyde in both humans and rats.”

“This review.” Dr. Soffriitti says, “is particularly urgent with regard to aspartame-containing beverages, heavily consumed by children.”

Michael Jacobson, executive director of Center for Science in the Public Interest, told Reuters reporter Maggie Fox in a telephone interview: “This is the second study by the same lab showing that aspartame causes cancer in rats.” “People can easily avoid products using Nutrasweet or Equal and keep these products away from kids,” Jacobson said.

Actually, when it comes to sweeteners quite a few people today may feel between a rock and hard place. With obesity and type 2 diabetes at near epidemic levels while massively powerful market trends keep pumping cravings for sweets (as well as for salt and fats), low calorie products have gone from fads to virtual “health foods” The need for diet foods with additives like aspartame will not abate without profound changes in eating habits. Worldwide, about 200 million people, according to the Calorie Control Council, consume aspartame.

References

First Experimental Demonstration of the Multipotential Carcinogenic Effects of Aspartame Administered in the Feed to Sprague-Dawley Rats
Environmental Health. Perspectives Volume 114, Number 3, March 2006, Morando Soffritti and team.

Also published in full text, free, at PubMed Central.

Lifespan Exposure to Low Doses of Aspartame Beginning During Prenatal Life Increases Cancer Effects in Rats