Don’t Panic: A new warning from the World Health Organization (WHO) regarding the potential of artificial sweeteners to cause cancer has caused some concern. However, it’s important to look at the science and context behind the decision. Aspartame was discovered in 1968 and has been used in many diet sodas and other foods and beverages since 1981. The Food and Drug Administration (FDA) continues to believe that it is safe. However, research has continued and studies published in 2006 argued against its use. study that suggests a correlation between aspartame and liver cancer but it’s not a solid link so the World Health Organization is still trying to figure out what to do
This pair of papers from the same research team found that rats given daily doses of aspartame had drastically increased rates of cancers of the blood and the nervous system. However, when these studies were published, other researchers argued that the researchers misdiagnosed what was wrong with the rats, as they had conducted neck Cropsies only after the rats had died of natural causes. This is not the typical way that animal research is done, as animals are usually raised under experimental conditions for a set amount of time and then euthanized to study them. Letting them die of natural causes introduces the possibility that the health issues discovered in the necropsy might have nothing to do with the experiment. Furthermore, other groups argued that what the team identified as tumors were actually inflammation or signs of bacterial infection in the rats, not cancer.
Even if it was cancer that killed these rats, there was another huge issue with this study: the amount of aspartame these rats were dosed with. Food Regulatory Agencies like the FDA calculate what a safe daily intake of a given substance might be. The assumption is that the dose makes the poison; even things that could theoretically be dangerous are usually fine in really small doses. So they define those really small doses and set limits on how much of that thing can be in any food product. For aspartame, the FDA’s safety limit is 50 milligrams per kilogram of body weight. So for someone weighing about 6.68 kilograms, they’d need to consume over 3,400 milligrams of aspartame to exceed that limit. Since a can of Diet Coke contains a little under 200 milligrams of aspartame, that means you’d need to drink almost 18 cans per day to exceed that threshold. However, some of the rats in this study were given doses of aspartame equivalent to a human consuming 5,000 milligrams per kilogram of body weight, which is astronomically high. It’s literally the equivalent of those rats drinking over 26 sodas a day (not rat-size sodas- regular 12-ounce ones). In the entire experiment, only two doses of aspartame that these rats were exposed to are below the FDA’s acceptable limit.
Another study by that same team looked at aspartame’s effects on mice and found that daily aspartame intake was correlated with increased rates of liver and lung cancers, but only in male mice. Aside from that, it’s important to remember that humans are not rodents, so the next step in figuring out whether aspartame might be related to health risks in humans is to follow a bunch of humans who consume it and just see what happens. This is what’s called a longitudinal study, where researchers take a large cohort of people, get their baseline data, and follow them over the course of several years to see what changes occur in their overall health.
In response to that rat study in 2006, a team of researchers at the American Association of Cancer Research published the results of their longitudinal study. It looked at adults who consume varying amounts of aspartame and the rates at which they developed blood and nervous system cancers. The result was no correlation between the use of aspartame and cancer. It’s important to remember that the study was looking at people who consumed aspartame in a range of quantities.
In 2022, another study was published that found that consumption of aspartame was correlated with higher risks of breast cancer and cancers related to body weight. This more recent study also found that there was an increased risk of cancers with consumption of artificial sweeteners, which is both interesting and extremely vague. The World Health Organization is still trying to figure out what to do, as the new warning is for liver cancer, and there is only one study that suggests a correlation between aspartame and liver cancer, but it’s not a solid link.