Do some searching on the web or just listen to your well-meaning friends next time you reach for a diet drink. It happened to me again yesterday. I opened the fridge and took out a Coke Zero and my friend immediately said "Don't drink that - it's got that poisonous aspartame stuff in it!" Regardless of my answer, I was unable to change his conviction that he was saving me from a terrible fate.
If you are a type 2 diabetic and that hasn't happened to you yet, rest assured, it will. The sweetener police are a Special Squad of the Diet Police, always out to save us from ourselves.
Let me put it politely and succinctly. It is ALL utter nonsense.
We can thank a few individuals for this myth. The truth is lost in the mists of time. This anti-aspartame web-page claims that a certain Betty Martini was the originator, but this equally anti-aspartame page is dedicated to Nancy Markle (original link is gone by 2016, I have linked to the Wayback Machine archive) who is more often accredited with the "discovery." Some believe they were the same person. There are several disciples on the web these days, busily spreading the gospel according to Nancy Markle (note added 11th March 2011. That Nancy Markle page has disappeared and the various Betty Martini web-pages now claim Markle never existed).
If you do some searching on the web you will find that the followers of these kooks are very web-savvy and have ensured they will be on the first page of your search results. If you have the time, read some of them. You will find a web of inter-woven "supporting" research papers, some real, some not, most quoting each other, rarely peer-reviewed by any reputable journal and most performed using unlikely levels of aspartame on unrepresentative rodents.
On the other hand, if you go to more reputable sites such as the US National Cancer Institute, a division of the US national Institutes of Health, you will find some more credible references. Their summary (the emphasis is mine) is as follows:
"A study of about half a million people, published in 2006, compared people who drank aspartame-containing beverages with those who did not. Results of the study showed that increasing levels of consumption were not associated with any risk of lymphomas, leukemias, or brain cancers in men or women.
Researchers examined the relationship between aspartame intake and 1,888 lymphomas or leukemias and 315 malignant brain cancers among the participants of the NIH-AARP Diet and Health Study from 1995 until 2000. Development of these cancers was not associated with estimated aspartame consumption, refuting a recent animal study with positive findings for lymphomas and leukemias and also contradicting claims regarding brain cancer risk."
As a person with leukemia, those conclusions were of direct interest to me. I should note that I rarely consumed aspartame in any form before my double-diagnosis in 2002; I have consumed it daily since. Both conditions have improved; I don't credit that to aspartame, I am just making the point that neither got worse.
2016 note: that report is no longer available on the web. This is the orginal study underlying the assessment (pdf): Consumption of Aspartame-Containing Beverages and Incidence of Hematopoietic and Brain Malignancies
Results: During over 5 years of follow-up (1995-2000), 1,888 hematopoietic cancers and 315 malignant gliomas were ascertained. Higher levels of aspartame intake were not associated with the risk of overall hematopoietic cancer (RR for z600 mg/d, 0.98; 95% CI, 0.76-1.27), glioma (RR for z400 mg/d, 0.73; 95% CI, 0.46-1.15; P for inverse linear trend = 0.05), or their subtypes in men and women.
Conclusions: Our findings do not support the hypothesis that aspartame increases hematopoietic or brain cancer risk. (Cancer Epidemiol Biomarkers Prev 2006;15(9):1654 – 9)
Similarly, another organisation that gives credible support using reputable studies for their conclusions about aspartame is Green Facts. You can read their reports here: Scientific Facts on Aspartame.
For further reading, start with Snopes: Kiss my Aspartame
No matter what food substance you test someone, somewhere will have problems with it. Of course some people will have problems with aspartame. Some people have deadly problems with peanuts, or fish, or gluten or even lactose. But that does not mean that any of those substances necessarily have any dangers, if ingested in moderation, for the rest of us.
I have also consumed almost all of the other artificial sweeteners available to us these days, including Splenda, saccharine, and several others. None have harmed me in any way.
I repeat, I never drank diet sodas until AFTER my cancer and diabetes diagnoses and the only effect it has had on me has been to let me enjoy soft drinks without harming my blood glucose levels.
You must make your own judgement and test for yourself.
Everything in Moderation - Except Laughter
PS. Comments from the kooks will not be published, so don't waste the effort of typing.