For as long as artificial sweeteners have existed, people have been warned about their supposed health risks such as cancer and multiple sclerosis. But while these claims are routinely debunked as nothing more than junk science, some research—including a new study presented this week at the annual Experimental Biology conference—is beginning to indicate that sweeteners could actually contribute to health problems like type 2 diabetes.
Researchers at the Medical College of Wisconsin and Marquette University used rats vulnerable to developing diabetes for their experiments. For three weeks, different groups were fed high doses of two sugars, glucose and fructose, and two common artificial sweeteners, aspartame and acesulfame potassium. They then studied the rats’ blood using a large-scale technique that tracks minute metabolic changes, known as metabolomics.
“Just after three weeks of giving these sweeteners and sugars to our diabetes-susceptible rats, we saw biochemical changes in the blood that could potentially lead to alterations in fat and energy metabolism,” lead author Brian Hoffman, a biomedical engineer at both institutions, told Gizmodo.
Diabetes is what happens when our bodies become unable to maintain proper glucose levels in the body—a process that’s largely regulated by the hormone insulin. This breakdown causes people to either stop responding to insulin as easily as they once did, or to stop producing insulin altogether. Excessive sugar in our diets is thought to help cause diabetes by overtaxing the body’s insulin-producing machinery, since it’s used to bring high blood glucose levels back to normal.
Because of that, artificial sweeteners have long been advertised as a way for people to eat treats and soft drinks safely and lose weight, without raising the risk of diabetes. But rates of diabetes and obesity have continued to skyrocket regardless, even as sweetener-rich foods and drinks became widely available starting in the 1950s. (There are currently six FDA-approved artificial sweeteners.)
As a result, Hoffman and his team have not only tried to understand how sugar sparks the chain of events that leads to diabetes, but also tried to suss out whether sweeteners could do the same.
If sweeteners can raise our risk of diabetes, Hoffman says, they probably do it differently than sugar. Rather than overwhelming the body’s machinery, his and others’ research suggests, fake sugar wears it out. “Sweeteners kinda trick the body. And then when your body’s not getting the energy it needs—because it does need some sugar to function properly—it potentially finds that source elsewhere,” Hoffman said.
In the rats’ blood, his team found evidence of protein breakdown, likely meaning their bodies turned to burning away muscle as a source of energy. They also found higher levels of lipids and other fats, which over time could contribute to obesity and diabetes. Other research has suggested sweeteners alter the community of bacteria that call our guts home—the microbiome—in a way that could lead to harmful metabolic changes. And still more research has shown that diets high in artificial sweeteners are associated with a greater risk of diabetes and obesity.
Hoffman is well aware of past efforts to tie sweeteners to dire health risks, but he says things are different in this case.
“Most of these sweeteners were approved well before we had the technology to perform studies like my lab is doing. So they weren’t able to look as in-depth at some of the potential effects being caused,” he said. “By knowing what biochemical changes these are causing through these large-scale studies, we can take a unbiased approach and see what’s changing to give us a better direction.”
Hoffman’s team plans to submit their current findings for consideration in several peer-reviewed journals, but they’re already in the middle of studying their sweetener-fed rats for longer periods of time. Future studies are likely to involve taking a peek at the rats’ microbiomes too. Ultimately, he believes their study method could be relatively easy to use with people, since all that would be needed is a blood sample to study small metabolic changes.
In the meantime, though, he doesn’t necessarily want to scare anyone away from their diet drink habit.
“What I like to tell people is that most things in moderation are going to be fine. So if you enjoy your diet soda here and there, than have your diet soda here and there. If you like your normal soda here and there, have it here and there,” he said. “It’s when people start to chronically consume these—say, a person drinks two, three, four of [these drinks] everyday, that we should start to be concerned. Because you’re starting to introduce these biochemical changes and the body has no time to recover.”
Update: The American Beverage Association, a trade group that represents the non-alcoholic beverage industry, reached out to Gizmodo after this article was published, and offered this response to the study’s findings:
“Low-calorie sweeteners have been proven safe by worldwide government safety authorities as well as hundreds of scientific studies and there is nothing in this research that counters this well-established fact.”