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The Truth about Aspartame

The artificial sweetener aspartame is falsely accused of being the cause of nearly every disease.  

by Brian Dunning

Filed under Conspiracies, Urban Legends

Skeptoid Podcast #127
November 11, 2008
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Also available in Chinese | Russian


As a kid I remember hearing that the artificial sweetener aspartame would neutralize your digestive enzymes, and anything else you ate that day would turn to fat. Although this makes no sense biochemically at any level, it sounded scientific enough to me and I was satisfied with it — at least enough to justify my dislike for its awful flavor. It turns out that my fat-producing claim was about the mildest of many arguments made by a growing anti-aspartame movement, and biochemically-nonsensical as it was, it was among the sanest of the arguments. Take a look at websites such as,, and, and you'll see that a whole new breed of aspartame opponents has taken activism to a whole new level. Here are a few quotes from those web sites:

Thank you Montel Williams for having the fortitude to say: "Multiple Sclerosis is often misdiagnosed, and that it could be aspartame poisoning"

NutraSweet® killed my mother and has killed and/or wounded millions of innocent people in the US and abroad.

Aspartame converts to formaldehyde in vivo in the bodies of laboratory rats.


Did O J Simpson Have a Reaction to Aspartame that led to the deaths of Nicole Simpson and Ron Goldman?


After more than twenty years of aspartame use, the number of its victims is rapidly piling up, and people are figuring out for themselves that aspartame is at the root of their health problems. Patients are teaching their doctors about this nutritional peril, and they are healing themselves with little to no support from traditional medicine.

Donald Rumsfeld disregarded safety issues and used his political muscle to get Aspartame approved.

The Nazi Scientist's Poison Projects: Poison adults with Aspartame

Because of your and/or your forbearers [sic] exposure to toxics like Aspartame, a summation of immune, mitochondrial, DNA, and MtDNA (genetic) damage has occurred in your body that has made your body unable to deal with chemical insults.

The doctor that was in charge of the lab to study Aspartame, reported that the substance was too toxic and he mysteriously dissappeared [sic] and all the paper work somehow was destroyed.

The Nazis actually won the war. They just pretended to lose so that we wouldn't notice them take over our government.

Well, that's enough for now. And if you haven't heard those, you've almost certainly received one of several hoax emails that people have been forwarding around since 1995, according to, giving an equally long list of untrue claims about aspartame being the cause of nearly every illness. One is even falsely attributed to Dr. Dean Edell. Suffice it to say that every possible kind of attack is made against aspartame: Pseudoscientific attacks where they throw out whole dictionaries of scientific sounding nonsense; guilt by association attacks where they mention aspartame alongside Adolf Hitler and Donald Rumsfeld; non-sequiturs like pointing out the evils of the corporate structure of pharmaceutical companies as if that is support for how and why an "aspartame detoxification" program will "heal" you of all disease; and even Bible quotations attacking aspartame. The anti-aspartame lobby appears to include everyone from alternative treatment vendors trying to sell their products, to fully delusional conspiracy theorists. Dr. Russell Blaylock, a retired surgeon turned anti-pharmaceutical author and activist, believes aspartame is part of a massive government mind-control plot:

We're developing a society because of all these different toxins known to affect brain function. We're seeing a society that not only has a lot more people of lower IQ, but a lot fewer people of higher IQ. In other words a dumbing down, a chemical dumbing down, of society. ...That leaves them dependent on government because they can't excel. ...So, you know, you can kind of piece it together as to why they are so insistent on spending so many hundreds of millions of dollars of propaganda money to dumb down society.

Discovered in 1965 at Searle (now Pfizer), aspartame is an artificial sweetener, aspartyl-phenylalanine-1-methyl ester. Chemistry types call it a methyl ester of the dipeptide of the amino acids aspartic acid and phenylalanine. It is 180 times as sweet as sugar, which is why it's such an effective low-calorie sweetener: It's needed in only miniscule amounts. Partly in response to all the anti-aspartame craziness out there, a group of scientists from the NutraSweet company published a 2002 review of dozens of studies and clinical trials performed worldwide in the journal Regulatory Toxicology and Pharmacology, which made the following conclusions:

Over 20 years have elapsed since aspartame was approved by regulatory agencies as a sweetener and flavor enhancer. The safety of aspartame and its metabolic constituents was established through extensive toxicology studies in laboratory animals, using much greater doses than people could possibly consume. ...Several scientific issues continued to be raised after approval, largely as a concern for theoretical toxicity from its metabolic components — the amino acids, aspartate and phenylalanine, and methanol — even though dietary exposure to these components is much greater than from aspartame. Nonetheless, additional research, including evaluations of possible associations between aspartame and headaches, seizures, behavior, cognition, and mood as well as allergic-type reactions and use by potentially sensitive subpopulations, has continued after approval. ...The safety testing of aspartame has gone well beyond that required to evaluate the safety of a food additive. When all the research on aspartame is examined as a whole, it is clear that aspartame is safe, and there are no unresolved questions regarding its safety under conditions of intended use.

And yet the claims persist unabated. Here are a few more, addressed point-by-point:

  • Claims that aspartame causes Multiple Sclerosis are entirely made up and have no evidence or plausible foundation. Search the Multiple Sclerosis Foundation's web site for "aspartame" to find more than enough information refuting this harmfully misleading claim.

  • The idea that aspartame causes "methanol toxicity" is based on the fact that when digested, aspartame does release a tiny amount of methanol. It's less than the amount you get from eating a piece of most any fruit. Tomato juice, for example, gives you four times the methanol of a can of diet soda. It's a common, naturally occuring environmental compound that is found in many foods. Nancy Markle, one of the most vocal aspartame conspiracy theorists, charges that the autoimmune disease lupus is actually misdiagnosed methanol toxicity caused by drinking 3-4 cans of diet soft drinks per day. If she's right, everyone who drinks a glass of tomato juice each day (or the equivalent in other fruits) is gravely ill with lupus. Time Magazine once devoted an entire article to debunking Nancy Markle's baseless claims about aspartame.

  • Much has been made of the claim that aspartame turns into formaldehyde in your system. This is true, because formaldehyde is a natural byproduct of digestion of methanol, and it happens whenever you eat almost anything. Formaldehyde is carcinogenic and is considered very dangerous in cases of occupational exposure, for example, when you get a dosage many orders of magnitude greater than the trace amounts produced during natural digestion. Again, aspartame does this in much smaller amounts than many common foods, so this has been a normal, healthy component of digestion for as long as humans have been eating fruits and vegetables.

  • Gulf War Syndrome is a weakly evidenced correlation between service in the Gulf War and incidences of chronic fatigue, chronic pain, and a range of vague neurological conditions. Anti-aspartame advocates blame aspartame for this, but there is no correlation between increased aspartame consumption and Gulf War service. In addition, aspartame is among the hypothesized causes that have been eliminated by the Research Advisory Committee on Gulf War Veterans' Illnesses.

  • What about Donald Rumsfeld's involvement with aspartame? He was the CEO of Searle at the time aspartame was approved as a sweetener. The reason he was hired was as a financial turnaround wizard, which he accomplished; he wasn't the guy in the lab designing artificial sweeteners. Even if you accept the conspiracy charges that he leveraged his cronies to force approval of a potentially dangerous product, that still says nothing about aspartame. It's a giant non-sequitur. To assess the safety of a product, we don't ask "Who was the CEO and who were his cronies?" we ask "What are the test results?" and so far, all of the test results show no association between aspartame and any of the diseases it is claimed to cause.

  • Some of the claims about aspartame breaking down into unwanted compounds are true at extreme levels of alkalinity or acidity, levels which would be fatal to a human being anyway. This is the case with many foods, by no means is this unique to aspartame. So if your body chemistry is such that aspartame would be a danger to you, you'd have to already be dead from some unrelated cause.

  • There is actually one known health risk associated with aspartame, but it only applies to people with a rare genetic disorder on chromosome 12 called phenylketonuria or PKU, which affects about 1 in 15,000 people. They can't metabolize phenylalanine, so they need to minimize not only aspartame but all phenylalanine products. Phenylalanine is an amino acid that's found in many, many foods, including breast milk; so it hardly makes sense to single out aspartame as the problem product.

  • It is true that you can't cook with aspartame, but not for any safety reasons. At cooking temperatures it breaks down and loses its flavor, like some other foods. For this reason aspartame is starting to lose ground in the market to Sucralose, another artificial sweetener that does retain its flavor when cooked.

When you hear claims that are supported only by a fringe minority that's in opposition to the scientific consensus, you have good reason to be skeptical right off the bat, but it doesn't mean it's not worth looking into. Aspartame has been looked into ad nauseum even after its approval, and found safe at every try; so at some point you have to depart from rationality to continue supporting the claims made against it. Enjoy your diet Dr. Pepper, it's not going to hurt you; if it was, I'd have been dead decades ago.

By Brian Dunning

Please contact us with any corrections or feedback.


Cite this article:
Dunning, B. "The Truth about Aspartame." Skeptoid Podcast. Skeptoid Media, 11 Nov 2008. Web. 30 Nov 2015. <>


References & Further Reading

Aaronovitch, D. Voodoo History: The Role of the Conspiracy Theory in Modern History. New York: Riverhead, 2010.

Butchko, H., Stargel, W., Comer, C., Mayhew, D., Benninger, C., Blackburn, G., de Sonneville, L., Geha, R., Hertelendy, Z., Koestner, A., Leon, A., Liepa, G., McMartin, K., Mendenhall, C., Munro, I., Novotny, E., Renwick, A., Schiffman, S., Schomer, D. "Aspartame: review of safety." Regulatory Toxicology and Pharmacology. 1 Apr. 2002, Volume 35, Number 2 Pt 2: S1-93.

Health Canada. "Aspartame." Food & Nutrition. Health Canada, 14 Oct. 2005. Web. 7 Oct. 2013. <>

Magnuson, B.A., Burdock, G.A., Doull, J., Kroes, R.M., Marsh, G.M., Pariza, M.W., Spencer, P.S., Waddell, W.J.,, R., Williams, G.M. "Aspartame: a safety evaluation based on current use levels, regulations, and toxicological and epidemiological studies." Critical Reviews in Toxicology. 1 Jan. 2007, Volume 37, Number 8: 629-727.

Novella, S. "Aspartame – Truth vs Fiction." Science-Based Medicine. Science-Based Medicine, 15 Sep. 2010. Web. 20 Feb. 2012. <>

Rulis, A.M., Levitt, J.A. "FDA's food ingredient approval process: Safety assurance based on scientific assessment." Regulatory Toxicology and Pharmacology. 1 Feb. 2009, Volume 53, Number 1: 20-31.

Stegink, L.D. "The aspartame story: a model for the clinical testing of a food additive." The American Journal of Clinical Nutrition. 1 Jul. 1987, Volume 46, Number 1: 204-215.


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