|
Sweetner Assessment Attracts Further Review
Aspartame has been a controversial substance and subject with some food activists critical of the
artificial sweetener, but its actual affect on human health can’t be determined by a bunch of sick rats, or at least that’s what a European Union Commission has decided.
Consumers have embraced artificial sweeteners, and their role is likely increase as Western populations age and diabetes becomes a bigger factor in public health. That being said, continued attacks on artificial sweeteners by groups who question either their safety or necessity, or both, are a factor in keeping consumers worried about sugar substitutes.
In a recently released study, Mintel International Group (website ) noted that 2005 sales of sugar-free foods and beverages reached a sweet total of $5.9 billion in the United States. Yet, although sales continue to grow, consumers are wary. Mintel reports that 60% of American adults say they are concerned about the safety of artificial sweeteners. "While the sugar-free market is expanding, there is concern and confusion among some medical professionals and consumers as to the safety of these products," said Mintel senior analyst Marcia Mogelonsky. "The public is confronted with an array of facts and statistics that elevate health concerns and raise the issue of whether sugar-free is worth the potential risk."
Flair ups in the controversy surrounding artificial sweeteners tend to occur when dramatic claims emerge from the research community and are conveyed with little scrutiny or skepticism by the press. So, when the European Ramazzini Foundation of Oncology and Environmental Sciences ( website ) published some fairly frightening conclusions from a study it conducted, and sought publicity for its findings, the European Food Safety Authority ( website ) had to re-enter the aspartame debate even though it already had determined the sweetener was safe.
When the study results began to make the rounds last year, EFSA reviewed the effort and published a summary of its opinion about the Ramazzini research that demonstrates why European authorities became concerned.
The European Food Safety Authority considered that the results of [the Ramazzini] study indicate that aspartame is a ‘multipotential carcinogenic agent,’ based on increases in malignant tumor-bearing animals, lymphomas/leukemias (primarily in female rats), transitional cell carcinomas of the renal pelvis and ureter, also in female rats, and malignant schwannomas of peripheral nerves. EFSA asked its Scientific Panel on Food Additives, Flavorings, Processing Aids and Materials in Contact with Food to review the study as a matter of high priority.
To reach its conclusions, Ramazzini methodology introduces a study vector into a large population of rodents lets them live out their life spans and looks at what diseases they have suffered. In this case, the test rodents were fed aspartame and left to live out their life spans, with Ramazzini conducting post mortems.
The Ramazzini methodology is designed to take a broad approach to studying cancer, one it maintains is more realistic than narrow studies conduced over a fixed period of time. The argument, basically, is that human beings consume suspected carcinogens over a lifespan.
Therefore, study protocols should take into consideration time, aging, cross-exposures to natural
and artificial substances, among other inputs, in assessing the cancer risk from substances such as aspartame.
Ramazzini is championing this approach as an important new tool to assess issues such as aspartame’s potential role in cancer. The foundation at least wants studies using its methodology to be considered alongside traditional approaches that concentrate more narrowly on test substances delivered to study animals over a fixed period of time. On the surface, it might seem as if it might be a sensible approach, yet, an EFSA spokeswoman said significant problems arise when you take the longer view. “There are pros and cons for both fixed duration two-year studies and for lifetime studies in rats,” said Dr. Carola Sondermann, EFSA senior press officer. She noted that, although most cancers develop later in life in humans, “lifetime exposure studies can miss carcinogens that are picked up by fixed duration, two-year studies and the majority of cancer bioassay scientists think it is best to end studies at two years.”
In other words, two-year studies – or bioassays – are the standard acknowledged by most experts in the field.
Lifetime exposure creates certain specific problems, Sondermann added. If researchers kill the test animals at an earlier and fixed time, a bigger difference between treated and control groups occurs. Conversely, if the animals die naturally, “you can miss this accelerated time-to-tumor. Also, more controls will have tumors at the same sites, so you can no longer distinguish, for commonly affected sites, between tumors that may have been induced by the chemical and
tumors induced simply by old age because repair mechanisms cope less well as age progresses,” she said.
The problems continue even after the test animal dies because biological reactions that occur when an animals dies may contaminate results, particularly when the technicians are not present to quickly preserve the creature.
In the face of the EFSA opinion, Ramazzini defended its work on the merits, but with just a hint of
outsider pique: Scientific Director of the European Ramazzini Foundation and primary author of the aspartame study, Dr. Morando Soffritti, M.D., underlined the importance of EFSA’s interest in the European Ramazzini Foundation’s aspartame study saying, “as the Director of an independent, non-profit institution, I consider it an important recognition to have our data carefully considered by EFSA…Prior long-term carcinogenesis studies on aspartame (4 total) were conducted over 20 years ago by the producers of the artificial sweetener using a small number of animals per sex per group. The results of these studies provided the basis for the current opinion regarding the non-carcinogenicity of aspartame.”
Although the Ramazzini statement suggests industrial sources are suspect, foundation spokeswoman Kathryn Knowles said that the critical point is to embrace the opinion of independent researchers, who we are led to assume have no axes to grind. She didn’t mention that independent researchers often have their own agendas.
“We don’t dispute industry findings per se. We do feel they should be examined with the same level of scrutiny as independent studies, if not more. For example, EFSA requested to view our pathology slides but did not make the same request of the industry-sponsored studies showing that aspartame is safe,” she said.
Sondermann said, however, that problems were detected with the few slides Ramazzini provided. “Whilst the authors have stated that care was taken to limit post mortem modifications, the occurrence of autolytic changes in tissues was noted by scientists from the U.S. National Toxicology Program who reviewed some of the slides from the aspartame study,” she said,
adding, “EFSA's scientific AFC Panel that reviewed the Ramazzini study on aspartame was composed of 19 independent scientific experts with a broad spectrum of experience and knowledge in the area within the remit of the panel.”
The Ramazzini defense addressed a problem EFSA noted in its methodology, the fact that many of its test animals were sick, saying that its method reflects the natural human life in which people may be exposed to agents in the industrial and general environments from birth until death.
“Since 80% of cancer is diagnosed in humans over the age of 55, it is of paramount importance to observe how an agent affects laboratory animals in the last third of their lives”, notes Soffritti, who further stated that “occurrence of chronic pulmonary inflammation is common in the natural dying process. Moreover, inflammation was observed in both animals that were treated with aspartame as well as in the control group.”
Sondermann asserted, however, “The AFV panel went through each critical tumor site that was considered by the Ramazzini Institute to show an effect. The panel did not consider the findings to show evidence of aspartame-induced cancer. These included lack of any convincing dose-response despite a 1,000-fold difference between the lowest and the highest doses; for lymphomas and leukemias, underlying respiratory disease in a high proportion of the animals, which by itself can lead to lymphomas, and for changes in the urinary tract, the fact that such changes are widely considered to be rat-specific.”
Essentially, too many rats in the test group were sick and too many cancers didn’t exhibit a biology that suggested a human risk. “On the basis of all the evidence currently available the panel saw no reason to revise the previously established Acceptable Daily Intake (ADI) of 40 mg per kg body weight. It should be mentioned that dietary exposure to intense sweeteners in the population has been assessed in a number of European countries and as regards aspartame intakes are up to 10 mg per kg body weight per day, which is well below the ADI,” Sondermann said.
Ramazzini’s look at the cancer risk of aspartame isn’t without merit. After all, looking at long-term
exposure to carcinogens may produce new insights. However, long-term studies also invite any number of outside influences that may, over time, produce outsized affects. The famous Brazilian butterfly, the one whose beating wings spawn a tornado in Texas, was first remarked upon to illustrate how small factors can become big ones given the right conditions.
So, ultimately, despite the controversy, it is still the overwhelming scientific consensus that aspartame is safe. Moreover, it is also safe to say that groups still will take aim at the sweetener and that their pot shots will command the attention of some reporters and consumers. Those pot shots, though, haven’t convinced the majority of scientists looking into cancer risk to change their minds or methodologies, or their conclusions.
By Mike Duff
return to editorial page
|
