A new study on the artificial sweetener aspartame may make diet soda lovers breathe a little easier.
A large federally financed study done by government researchers at the National Cancer Institute found no link between the consumption of aspartame and elevated risks of brain cancer and blood-related cancers like leukemia.
Aspartame is sold under the brand names NutraSweet and Equal and is found in drinks like Diet Coke, Diet Pepsi, Diet Snapple and Sugar Free Kool-Aid.
Fears about aspartame and cancer have plagued the artificial sweetener since it was first approved by the Federal Drug Administration in 1981 and were inflamed by an Italian study last summer done on rats. That study caused alarm because it showed an increased incidence of lymphoma and other cancers in rats that consumed the equivalent of four to five 20-ounce bottles of diet soda a day for a 150-pound person.
In contrast, the National Cancer Institute study, which looked at aspartame consumption among about 567,000 people from the ages of 50 to 69 and was presented at a research conference on Tuesday, showed no cause for concern, even among heavy users of aspartame.
The Calorie Control Council and the American Beverage Association, both of which represent beverage companies, hailed the study as further evidence that aspartame is a safe food additive.
But some scientists and consumer advocates have criticized the National Cancer Institute study as having weak methodology. To get information on people who consume aspartame, the study culled from broad-based food consumption surveys that were mailed out to the study participants. The 16-page surveys, which asked people to remember what they ate and drank for one year, were mailed out only once over several months, beginning in 1995.
Morando Soffritti, scientific director of the European Ramazzini Foundation and author of the Italian study on rats, said the National Cancer Institute researchers appeared to have collected no data on people's prior consumption, whether they were regular consumers of beverages with aspartame or whether they recently began consuming them.
The duration of exposure to aspartame is inadequate in the study, said Mr. Soffritti. "We know nothing about how long they've been consuming aspartame. One year is practically nothing."
Walter Willett, chairman of the department of nutrition at the Harvard School of Public Health, calls the lack of past data a "limitation. " He said that because of the size of the study it is likely that a strong correlation between brain and blood-related cancers and aspartame would still have probably shown up, but that a more subtle connection would not.
The study's authors may have been simply assuming that people do not change their dietary habits very often. The authors said they could not comment on their assumptions because the study has not yet been published in a medical journal.
Michael F. Jacobson, executive director of the Center for Science in the Public Interest, a nutrition advocacy group that is often critical of the food industry, said that because the study evaluated people aged 50 to 69 and then followed up for five years to check on the incidence of cancer, it may have failed to address the occurrence of cancer for people in their 70's and 80's.
Despite that, the findings do take much air out of the idea that aspartame causes cancer. Dr. Arthur Schatzkin, the principal investigator for the study, said he looked at people who consumed the equivalent of as many as six 20-ounce bottles of aspartame-containin g beverages a day and found no elevated incidence of lymphoma, leukemia or brain cancers.
Mr. Jacobson, despite his criticisms of the design of the study, called the findings "reassuring. "
"The Italian study says the risk is enormous and at such low doses, so if it was that bad you think you'd see something in this new study," he said.
After the Italian study, the Center for Science in the Public Interest called for the government to review aspartame's safety. "This is still something the government needs to review," Mr. Jacobson said.