Aspartame, a sweetener in Diet Coke and other low-calorie foods and drinks, is reportedly about to be named a “possible carcinogen” by the World Health Organization. That sounds bad, right? But it doesn’t mean that Diet Coke is likely to actually give you cancer. Let me explain.
The word “possible” is doing a lot of work here
When we hear it is possible that something might cause cancer, we stay away. It sounds like, well, that thing could give you cancer. But the International Agency for Research on Cancer uses those words differently.
When IARC, the WHO’s committee on assessing cancer risks, considers the evidence on whether something might cause cancer, they categorize it in one of the following groups:
Group 1: carcinogenic (this includes cigarettes, the HPV viruses that cause cervical cancer, and ionizing radiation)Group 2A: probably carcinogenic (this includes red meat, hot beverages, and working as a hairdresser)Group 2B: possibly carcinogenic (this is the group aspartame reportedly may end up in)Group 3: not classifiableGroup 4: probably not carcinogenic (this list contains zero items; a chemical called caprolactam was previously on it, but was moved to group 3)These are not designations of cancer risk, but of the chance that there is a detectable link of some kind. The “possible” or “probable” doesn’t refer to your chances of getting cancer, but to the chances of scientists eventually being able to find a definite link between that item and cancer. In other words, a “possible” (or even “probable”) carcinogen is one where we don’t know yet whether it causes cancer.
Should I stop drinking Diet Coke?
I was drinking a Diet Coke when I heard this news, and I’m drinking a Diet Coke now as I write this. I’m not saying I make the best personal choices, but maybe that will give you a sense of how I view this research.
If you look at the other things in Group 2B, you’ll see why the designation is pretty much meaningless to folks like you and me. (For scientists, it may help direct future research.) Group 2B also includes:
Pickled vegetablesAloe veraBeing a firefighterExhaust from gasoline enginesLeadNickel (the metal)ChloroformDDT (the pesticide)As you can see, it’s a pretty diverse list! Some of these things you would want to limit your exposure to. Lead, for example, is bad for us even if it turns out not to cause cancer. Pickled vegetables, on the other hand, are probably good for our gut bacteria and are generally regarded as a healthy food that we should be eating more of. You can’t meaningfully use the 2B list to decide how to live your life.
So it doesn’t really mean much that aspartame (or anything else) is on IARC’s “possible carcinogen” list. The World Health Organization has a different committee that rules on the safety of food additives, and it’s expected to deliver a verdict on aspartame on July 14, Reuters reports. This group will consider dosage and other real-world aspects of risk, so that will be the one to pay attention to if you’re concerned about new findings on potential health risks of aspartame.
