inFact with Brian Dunning inFact with Brian Dunning


The Truth about Aspartame

Is the popular artificial sweetener aspartame truly as poisonous as nearly every foodie website and movie makes it out to be, or is that just more shock-doc nonsense?

Share Tweet

Aspartame is an artificial sweetener. It's 200 times as sweet as sugar, so we only need to use a tiny amount of if in foods. Even though it has calories like sugar, we need so little of that it's considered zero calories.

But all kinds of urban legends surround it; if you listened to them all you'd think aspartame was the worst product ever. Let's take a look at some of these:

It Causes Methanol Toxicity!

When you digest it, aspartame does release a bit of methanol. But so do a lot of foods, like fruit, for example. When you drink tomato juice, it releases four times as much methanol as does the aspartame from a diet soda. I wouldn't worry about it too much.

It Turns into Formaldehyde in Your Body!

This is true, since formaldehyde is one of the byproducts of digestion. This happens when you eat almost anything. Although the word "formaldehyde" sounds scary and shocking, it's a perfectly natural compound found in our bodies, and has been for as long as people have been eating fruits and vegetables.

It Causes Multiple Sclerosis!

Only according to anti-aspartame activists. This goes back to a 1995 anonymous hoax email that's been circulating ever since, which claimed the Multiple Sclerosis Foundation was suing the Food & Drug Administration. Finally the Foundation had to put a notice on their website debunking this: "The MSF neither condemns nor endorses aspartame, and has never filed suit against the FDA".

Donald Rumsfeld Was the CEO When It Was Approved!

Therefore it's poisonous! He was indeed the CEO of Searle, the company that invented it. But this is 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?" So far, no tests have ever shown aspartame to be harmful.

Except to one small group of people: Those who have phenylketonuria. About 1 in 15,000 people have a rare genetic disorder and can't metabolize phenylalanine, an amino acid found in aspartame and a lot of other foods, including milk, so they have to avoid all of them.

Of course no product can be proven to be 100% safe, but decades of testing and re-testing of aspartame have failed to produce any evidence of health risk from aspartame. So drink up.

— Brian Dunning

Share Tweet


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.


Let us email you
about new and upcoming episodes:

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.