For decades, scientists have had a tough time figuring out what artificial sweeteners are really doing to our bodies.

To date, researchers have conducted over 210,000 different studies on the sugar substitutes.

But despite all the research, we still know remarkably little about the health effects of the powdery substances, which are often used to sweeten up drinks without piling on the extra calories of sugar.

The only thing we can say with any certainty is that consuming moderate amounts of artificial sweeteners probably won't cause cancer in humans.

But cancer risks aside, the jury is still very much out on whether sugar substitutes are any better for your body than regular sugar, and some scientists are growing increasingly worried.

"My recommendation is to not use artificial sweeteners," Ariel Kushmaro, a professor of microbial biotechnology at Ben-Gurion University, told Business Insider.

Artificial sweeteners might be bad for your gut

Kushmaro's latest research on artificial sweeteners was published in the journal Molecules last week.

According to his study, a collaboration between researchers at Ben-Gurion University of the Negev in Israel and Nanyang Technological University in Singapore, some of the most common artificial sweeteners we use may interfere with the way essential gut bacteria does its job.

For this study, Kushmaro and his team exposed a special kind of bioluminescent E. coli to common artificial sweeteners.

The researchers tried out all six sweeteners that the US Food and Drug Administration (FDA) has deemed safe, including aspartame (Equal, NutraSweet), sucralose (Splenda), saccharine (Sweet'n Low), and others. They even tried out athlete-targeted protein powders and flavoring packets that have those sweeteners as key ingredients.

After dosing the E. coli bacteria with artificial sweeteners "hundreds of times", Kushmaro concluded the sweeteners had a toxic, stressing effect, making it difficult for gut microbes to grow and reproduce.

The researchers think that a couple of artificially sweetened sodas or coffees a day could be enough to have an influence on gut health -and could even make it tougher for the body to process regular sugar and other carbohydrates.

That said, the researchers aren't certain, since they only tested the effects on E. coli and not in people.

"We are not claiming that it's toxic to human beings," Kushmaro said, "we're claiming that it might be toxic to the gut bacteria, and by that, will influence us."

Artificial sweeteners won't reduce appetite, or satisfy sugar cravings

His team is not the first to raise alarm. Another recent study of artificial sweeteners in rats suggested that artificial sweeteners can change the way their bodies process fat and energy. In the rats, this also led to muscle breakdown.

In humans, previous research has suggested that consuming artificial sweeteners is linked to higher rates of obesity, diabetes, high blood pressure, and strokes. Other studies have concluded that zero-calorie sweeteners can help people lose weight, but even that research points out that reduced calorie beverages won't dampen appetites.

There's even some limited evidence that artificial sweeteners might be tricking the brain into thinking we're not as satisfied as we are when consuming regular sugar, which could lead us to eat and drink more.

Kushmaro is planning to run more tests of gut bacteria in the hopes of zeroing in on the mechanisms at work in an artificial sweetener-altered human gut.

"In the last few years, we're getting to appreciate how important these microbial communities are," he said.

Consumers are already starting to shy away from these kinds of sugar replacers, opting for stevia leaf-based sweeteners instead. Sales of stevia grew nearly 12 percent in the US last year, while aspartame slid 8 percent and sucralose and saccharin were both down around 6 percent, according to Food Navigator.

Researchers are still cautious about all artificial sweeteners, including stevia, because research studies to date have painted a confusing picture of their potential health benefits and harms.

Stevia leaf is still not FDA-approved in the US, and there are some concerns about its effect on kidneys, reproductive health, blood sugar control, and the cardiovascular system.

In short, if you want to be good to your belly, it's probably best to limit your intake of sweets of all kinds, both the sugary and the sugar-free.

This article was originally published by Business Insider.

More from Business Insider: