A popular zero-calorie sweetener is being linked to an increased risk of heart attack and stroke. Known as erythritol, the sugar substitute occurs naturally at low levels in some plants, like grapes and mushrooms, but is also produced industrially and added to food at higher concentrations. In particular, it’s often used to sweeten low-calorie, low-carbohydrate and ‘keto’ products, which are typically high-fat and low-carbohydrate.

Researchers from the Cleveland Clinic in Ohio evaluated more than 4,000 Americans and Europeans who were undergoing cardiac evaluation and found that those with the highest blood concentration of the artificial sweetener were at an increased risk of experiencing a heart attack or stroke in the following three years. Notably, the majority of the participants already had some form of cardiovascular disease or exhibited risk factors for developing cardiac issues in the future, such as diabetes or high blood pressure. “People are trying to do something healthy for themselves, but inadvertently may be doing harm,” Dr Stanley Hazen, a cardiologist at the Cleveland Clinic, said.

In laboratory experiments, erythritol boosted the activity of platelets – a type of blood cell that sticks together to form clots – causing clots to form at a faster rate. Similarly, in mice injected with erythritol, clots formed more quickly after injury than they did in mice injected with saline. The team also took blood samples from humans who’d had an erythritol-sweetened drink, finding that their blood levels of the sweetener peaked within hours and remained high for two days – high enough that it could potentially affect their blood clotting.

Increased clotting has the potential to cause a heart attack or stroke because blood flow becomes constricted as clots form. “Every way we looked at it, it kept showing the same signal,” Hazen said. However, it’s worth noting that there were some limitations to the study, particularly that many participants were more than 60 years old and already had heart disease, meaning they were already at some risk of heart attacks and stroke. While the study showed some connection between clot formation and erythritol, it did not show the compound actually caused strokes and heart attacks in humans.

“[This study is] extremely important, and it will likely trigger immediate changes in what we consume,” Greg Neely, a professor of functional genomics at the University of Sydney who was not involved in the study, said. “We don’t fully understand what the health consequences of industrialised food have been, and just because something is sold as ‘natural’ doesn’t mean it is safe or good for us to consume at an industrial scale.” The study authors concluded that “studies assessing the long-term safety of erythritol are warranted.” ■