This Extremely Popular Artificial Sweetener Is Linked to Blood Clots, Study Shows

Low-calorie sweeteners are having a rough go as of late. Last July, the World Health Organization warned of aspartame’s possible cancer-causing properties in humans. (Our analysis of that here.) Now, researchers have found a link between consuming large amounts of the low-calorie sweetener xylitol and an increased risk of heart attack, stroke, and death. Xylitol is a sugar alcohol that sweetens many reduced-sugar foods, baked goods, chewing gums, and toothpastes. The team, led by researchers at the Cleveland Clinic, published their findings today in the European Heart Journal.

“We gave healthy volunteers a typical drink with xylitol to see how high the levels would get and they went up 1,000-fold,” senior study author Stanley Hazen, director of the Center for Cardiovascular Diagnostics and Prevention at the Cleveland Clinic, told CNN.

Crucially, this study found an association, not a causation between xylitol and poor health outcomes. Crucially, this means they didn’t find a direct mechanism that showed xylitol directly caused these poor health outcomes. The team acknowledges that further research into the compound’s effects on long-term cardiovascular health is necessary.

Hazen and his team investigated health risks associated with xylitol in over 3,300 adults in the U.S. and Europe. First, the team checked overnight fasting blood samples from participants to measure their xylitol levels. Then, over three years, the researchers found that one-third of participants with the highest levels of xylitol in their blood were more likely to suffer a cardiovascular event.

The researchers also looked at xylitol’s effects in the laboratory. Specifically, they looked at effects on cells called platelets, which clot together to prevent bleeding during injury. However, they can also clot inside vessels, affecting blood flow to essential organs, which raises the risk of stroke and heart attack. Mice who had received xylitol injections displayed significantly faster clot formation, and human platelets incubated with xylitol were prone to clotting.

The team also looked at platelet activity in 10 people. Participants drank xylitol-sweetened water and, after 30 minutes, showed a 1000-fold increase in xylitol levels in their blood. Platelets also appeared prone to clotting, most of all in those with the highest levels of xylitol.

Hazen cautions against alarm, mentioning this is an opportunity for consumption awareness. “It does not mean throw out your toothpaste if it has xylitol in it, but we should be aware that consumption of a product containing high levels could increase the risk of blood clot related events,” he said in a press release.