Present in many everyday foods, the sugar substitute known as xylitol is now under scientific scrutiny for its potentially harmful effects on health. Recent research from the US suggests that this natural sweetener, sometimes called birch sugar, may promote the formation of blood clots and, by extension,the risk of strokes and heart attacks.

“This study again shows the immediate need for investigating sugar alcohols and artificial sweeteners, especially as they continue to be recommended in combating conditions like obesity or diabetes,” said Dr Stanley Hazen, chair of cardiovascular and metabolic sciences at Cleveland Clinic’s Lerner Research Institute.

Hazen, who led the research, and his colleagues evaluated the effects of xylitol, a sugar substitute frequently used in certain confectionery products, chewing gums and toothpastes. The research involved a large-scale patient analysis, preclinical research models and a clinical intervention study.

Involving more than 3,000 American and European patients, the research – published in the European Heart Journal – identifies an association between xylitol and an increased risk of cardiovascular events, such as stroke and heart attack.

The researchers note that one-third of patients with the highest levels of xylitol in their plasma were more likely to suffer a cardiovascular event. They also report that, in preclinical testing, xylitol was associated with platelet coagulation and an increased risk of thrombosis.

This is not the first time the research team in question has shed light on the harmful effects of a sweetener on health. Last year, a similar association was made between cardiovascular risk and erythritol, which is also found in certain foods and beverages.

“Xylitol is not as prevalent as erythritol in keto or sugar-free food products in the US but is common in other countries,” the researchers explained. However, the scientists’ conclusions state that it is “high levels” of xylitol that increase the risk of cardiovascular events.

This is an important detail, especially since the research demonstrates an association, not a direct cause-and-effect link.

“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,” Hazen noted.

This finding leads the scientists to state that further research is needed to assess the cardiovascular impact of this sweetener. In the meantime, they advise talking to your doctor or dietician “to learn more about healthy food choices and for personalized recommendations”.