A seven-year study of aspartame (NutraSweet) comes down on the side of cancer risk. Unlike prior aspartame studies, Dr Morando Soffritti’s group from Bologna used dosage ranges in rats which, mg. per kg. were in the range of what a heavy diet soda drinker might consume… and these resulted in increased rates of leukemias, lymphomas and other tumors, although the New York Times piece does not say how much the relative risk was increased. Predictably, the Calorie Control Council — an artificial-sweetener industry trade group with the manufacturers’ interests, not those of consumers of low-calorie foods, at heart — objects. One of their points is that the rats exposed to the aspartame had been allowed to live until their natural deaths, longer than the two-year standard established by the United States government’s National Toxicology Program, so the cancers could have been from causes other than the aspartame. Pretty absurd objection, first, because I am confident that the methodology compared cancer rates with known background rates in rats. And many studies which are investigating subtly-developing delayed effects will appear to have negative findings if the duration of the study is arbitrarily limited.

The Soffritti study was motivated by inadequacies in the original pharmaceutical industry studies of the ’70’s used to establish the safety of the additive. Incidentally, for a decade encompassing much of the approval process for aspartame, Searle was headed by none other than Donald Rumsfeld. The FDA had found that the Searle studies had been so poorly conceived and executed that it had asked the Justice Dept. to open a grand jury investigation into whether they were fraudulent. Lo and behold, Samuel Skinner, the U.S. attorney handling the investigation, was hired by a law firm which had a plum contract with Searle and later appointed George W. Bush’s transportation secretary. The deputy who handled the investigation after Skinner left was also hired by the same law firm. A grand jury has never been convened. An independent panel reviewing Searle’s own data concluded that one of the studies had shown an increased incidence of brain tumors in rats fed aspartame and suggested that approval of the additive be withheld pending further studies. They were overruled by an FDA commissioner who granted approval to aspartame a short while after his appointment. Shortly after, he left and joined the public relations firm which represented Searle. But the Calorie Control Council says it is absurd to think that Searle was trying to influence government regulation with lucrative job offers. Looking at one five-year period of aspartame studies in medical journals, one critic found that, while 74 of 74 industry-funded studies found that the additive is safe, 84 of 92 independently funded articles identified health concerns.

In my own field of psychiatry, many practitoners feel that aspartame exacerbates mood and anxiety disorder symptoms and that treatment is easier if it is eliminated from the patient’s diet. Aspartame is made up of the two amino acids phenylalanine and aspartic acid, the former of which is speculated to upset neurotransmitter balance. The carcinogenicity studies speculate that the morbidity and mortality may be accounted for by the metabolism of aspartame to methanol and thence to the known carcinogen formaldehyde.

The abstract and full text of the Soffritti study are available here, from Environmental Health Perspectives.