Anti-aspartame web sites only provide data that supports their pre-determined point of view. They don't present all the data available. Previously this page only presented data found on anti-aspartame sites (which I continue to include below, for completeness). I still believe the original cancer research should be redone, despite the results of the Gurney study. This issue needs to be cleared up once and for all.

Further research of the aspartame link to cancer led me to a 1997 study conducted by Gurney JG, et al. This study, funded by the National Institute of Health, tested if aspartame consumption was correlated with increased brain tumor risk in children as hypothesized by Olney (1996). The Gurney study found no evidence "to support the hypothesis that consumption of aspartame is related to pediatric brain tumor incidence." See Dr. Dean Edell Good News about Aspartame and Environmental Toxicology Newsletter (about 1/5 down the page, search for the word 'aspartame').

The Olney paper looked at increases in brain tumors and made the hypothesis that these increases occurred at a time when aspartame consumption was on the rise and could therefore be due to aspartame. No other proof was provided other than this correlation. He did not look at individual cases of brain tumors. His goal was to stimulate further research--which it did, in the form of Gurney's study.

The aspartame critics have cited Olney's paper over and over as "proof" that aspartame is linked to cancer. For a small sample, see:
Study Links Brain Tumors to Aspartame
Brain Tumors and Aspartame
Brain Tumors Linked to Aspartame

Yet they fail to mention anything about the Gurney study, which has far more convincing data, since it looks at specific cases where brain tumors occurred, rather than making statistical generalizations.

This is a classic example of how the anti-aspartame sites give biased coverage of the available scientific research. And a closer look at the Gurney study shows that it meets almost all of the criteria for "good" research according to Mark Gold, the anti-aspartame research expert (see his web page Minimum Requirements For High Quality Research). Specifically:

1) This was research done on humans, not animals. The response to aspartame between humans and other mammals differs greatly, and there is much debate on "equivelant dosages". Good research should always use humans. Mark Gold states: "Therefore, aspartame tests in animals, especially those which tested for the effects of methanol and phenylalanine in rodents, or methanol and aspartic acid effects in monkeys should be ignored..." (bottom of page).

2) This research used "real-world" products in a real-world setting, not aspartame in capsule form. The hypothesis is that aspartame breaks down in these products and that these breakdown products may be the cause of aspartame reactions.

3) This research was conducted by a grant from the National Institute of Health, the only organization that is entrusted with doing aspartame research by Mark Gold's criteria.

4) This research used young children as subjects, the most susceptible population. See middle of page in What You Don't Know Can Hurt You. Chemical toxicity is measured in the dose per body weight. With such low body weight, children need to consume far less aspartame to approach the FDA "acceptable daily limit". This study examines aspartame usage in children, and Olney believes children should not be allowed to consume aspartame at all, ie, they are at the highest risk of developing brain tumors due to aspartame.

Despite meeting all these criteria, this study is not mentioned anywhere on any anti-aspartame site. Can you guess why? Could it be that it supports the safety of aspartame? The anti-aspartame web sites continue to circulate information regarding the original cancer trials as proof in itself that aspartame causes cancer in humans, despite other evidence, such as this study by Gurney. But these early studies use laboratory mice, and the anti-aspartame activists agree that the best research is on humans. The above study, which uses humans, has found no link between aspartame and brain tumors.

Below is my examination of anti-aspartame content that links aspartame to cancer, specifically brain tumors. This evidence must be taken together with the evidence above. Decide for yourself.

The scare sites claim that the original cancer research conducted by Searle (Nutrasweet is manufactured by Searle) was seriously flawed. After reading the Bressler report and the letter by Dr. Adrian Gross, as well as reading the abstract of "the Japanese study" (Ishii, 1981) that shows aspartame does not effect tumor growth, I would have to agree.

From the FDA statement:

"A Public Board of Inquiry (PBOI) was convened in 1980 by the Agency to review the scientific data presented by G.D. Searle and Company relating to the safety of aspartame. These independent scientific advisors to the Agency concluded that aspartame did not cause brain damage. At the same time, they said that there was not sufficient scientific evidence presented to the PBOI that aspartame did not cause brain tumors in rats. Therefore, the PBOI recommended against approval of aspartame at that time and concluded that further study was needed."
     "In 1981 after extensive review of the record by FDA scientists, then Commissioner Arthur Hull Hayes approved aspartame as a food additive."

The statement goes on to say that the PBOI later gave aspartame their "unqualified approval"--yet does not specify what evidence changed their minds. If the study by Ishii was the only evidence that changed their opinion, their judgement is debatable.

The 1981 study by Ishii uses over twice the sample size of the original experiment and it is done on a different breed of laboratory rat. Otherwise, it seems to be a duplication of the original research as mentioned in the Bressler report and in the letter by Dr. Adrian Gross: a two years study where rats were fed either 1000, 2000 or 4000 mg/kg of aspartame.

The Ishii results do show that the group of rats fed aspartame did in fact have more tumors than the control group, but this difference did not reach statistical significance. Thus, the researchers concluded that they found no statistically significant differences in the incidence of tumors between the control or the aspartame-fed groups.

But the results of the Ishii study are debatable because one of the rats in the control group had a tumor, and this statistically negated the impact of the tumors in the aspartame-fed group. It's very suspicious that a control group rat had a tumor simply because the spontaneous incidence of tumors in this breed of rat is much, much lower than that which occurred in this experiment. See Mark Gold's web page (about halfway down, quoting Dr. Olney regarding statistical manipulation).

Furthermore, there is a statistically significant difference in the results of the two studies--yet they are basically the same experiment. Both studies have questionable results. Although this is a far cry from saying that there is clear evidence that aspartame causes cancer, it's easy to see how political pressure may have bent the FDA to approve aspartame despite these findings, as opposed to doing more research.

The Bressler report shows that the original research may have been flawed, but it was flawed in that it under-reported abnormalities. There is no evidence of flaws that would have caused the aspartame-fed group to get tumors. If there was some extraneous cause of cancer in the original experiment, both the control and the experimental groups would have had similar problems (thus, the reason you run control groups). But this is not what they observed: the aspartame-fed group had significantly more tumors and abnormalities than the control group (as reported by Dr. Gross). There was also an increase in tumors with the increase in aspartame dosages, and this is further evidence that the tumors were not due to extraneous factors.

Both these studies were conducted in the laboratories of aspartame manufacturers, not by independent researchers. Together with the Bressler report, which provides evidence that the manufacturers of aspartame cannot be trusted to conduct experiments on their own products, I have good reason to agree with the analysis by the Center for Science in the Public Interest (CSPI): This research should be duplicated with larger numbers at an independent laboratory.

If we trust the data from the first experiment, what are the chances of getting brain tumors due to aspartame? This is the statistical analysis by Dr. Gross on the original experiment results:

My understanding of this data is that it shows that if one thousand people consume 50mg/kg of aspartame (the current acceptable limit set by the FDA), that one person will probably get a brain tumor due to aspartame. More importantly, it shows that if ten thousand people consume 10mg/kg/day of aspartame (approximately three diet soft drinks) one person out of this sample will probably get a brain tumor due to aspartame. This is a completely unacceptable risk, in my opinion.

An open question is what risk would you calculate if you pooled the data of both these experiments together. We can only hope that the FDA did this type of analysis and that is the basis of their approval of aspartame... but this isn't exactly reassuring, is it?