The quest for guilt-free, “healthier” sugar options has had a serious, unintended consequence — the proliferation of two highly virulent superbugs, a study published in the journal Nature claims.

The seemingly innocuous, naturally occurring sugar trehalose, a popular sweetener in nutritional drinks and energy products, could have allowed certain strains of the Clostridium difficile bacteria to become much more virulent than they were before, according to the study, which was published Wednesday.

The bacteria — which cause colitis and can lead to severe diarrhea and death — has had a resurgence in hospitals across the country, baffling doctors and scientists alike who can’t understand what has driven the uptick, the Los Angeles Times reported.

Nearly half a million Americans suffered from the infection in 2011, according to the Centers for Disease Control and Prevention. About 29,000 of those patients died within 30 days of the diagnosis and about 15,000 of those deaths were directly linked to the bug.

So what does a Stevia-esque sweetener have anything to do with it?

Scientists from Baylor College of Medicine in Texas decided to examine two particularly successful strains of C. difficile, RT027 and RT078, to try to understand the resurgence.

They examined the strains’ carbon-rich food sources and discovered both types were very good at using low concentrations of trehalose as their only carbon source, which they feasted on. The bacteria improved its ability to metabolize the sugar and scientists believe that improvement led to more C. difficile toxins, which is what made the bacteria more virulent.

There’s another reason scientists think trehalose is fueling the superbugs—timing. Both trehalose and C. difficile-related illnesses started to proliferate around the same time.

“Although considered an ideal sugar for use in the food industry, the use of trehalose in the United States and Europe was limited before 2000 owing to the high cost of production (approximately U.S. $700 per kilogram),” the authors in the study pointed out, according to the LA Times.

“The innovation of a novel enzymatic method for low-cost production from starch made it commercially viable as a food supplement (approximately U.S. $3 per kilogram).”

While the study is not 100 percent conclusive, the findings have been called “compelling.”

“Despite these concerns, the correlative findings of Collins and colleagues’ study are compelling,” Jimmy D. Ballard from the University of Oklahoma Health Sciences Center, who was not part of the study, wrote in a commentary.

“It is impossible to know all the details of events surrounding the recent C. difficile epidemics, but the circumstantial and experimental evidence points to trehalose as an unexpected culprit.”