Once again the safety of sugar substitutes is being questioned.
Researchers led by the Cleveland Clinic linked xylitol, a low-calorie sugar substitute, with an increased risk of heart attack, stroke or deaths related to cardiovascular disease, according to a study published today in the European Heart Journal.
Xylitol is a sugar alcohol found in small amounts in fruits and vegetables, and is also produced by the human body. As an additive, it looks and tastes like sugar but has 40% fewer calories. It is used, in concentrations much higher than those found in nature, in chewing gum, candy, toothpaste, and sugar-free baked goods. It can also be found in products labeled “keto-friendly,” particularly in Europe.
The same research team found a similar association last year with the popular sugar substitute erythritol. The use of sugar substitutes has increased significantly over the past decade as concerns grow about rising obesity rates.
“We're adding these things to our food pyramid, and the people who are most likely to consume them are the ones who are most at risk” of heart attack and stroke, such as people with diabetes, the leader said. author, Dr. Stanely Hazen, chair of cardiovascular and metabolic sciences at the Lerner Research Institute at the Cleveland Clinic.
Many heart attacks and strokes occur in people who have no known risk factors, such as diabetes, high blood pressure, or high cholesterol levels. The research team began studying sugar alcohols naturally found in the human body to see if the compounds could predict cardiovascular risk in these people.
In the study, researchers measured the level of natural xylitol in the blood of more than 3,000 participants after an overnight fast. They found that people whose xylitol levels placed them in the top 25% of the study group had about twice the risk of having a heart attack, stroke or death in the next three years compared to people in the bottom quarter.
The researchers also wanted to understand the mechanism at work, so they fed xylitol to mice, added it to blood and plasma in a laboratory, and gave a drink containing xylitol to 10 healthy volunteers. In all of these cases, xylitol appeared to activate platelets, which are the blood component that controls clotting, Hazen said. Blood clots are the leading cause of heart attacks and strokes.
“All it takes is for the xylitol to only interact with the platelets for a very short period of time, a matter of minutes, and the platelets become overloaded and much more likely to clot,” Hazen said.
The next question is what causes natural xylitol to be elevated in some people and how to reduce it, said Dr. Sadiya Khan, a cardiologist at Northwestern Medicine's Bluhm Cardiovascular Institute and professor of cardiovascular epidemiology at Northwestern Feinberg School of Medicine, who was not involved. in the new study.
Much more research needs to be done, Hazen said. In the meantime, he tells patients to avoid eating xylitol and other sugar alcohols, spellings of which end in “itol.” Instead, she recommends using modest amounts of sugar, honey, or fruit to sweeten foods, adding that toothpaste and a stick of gum probably aren't a problem because very little xylitol is ingested.
The report had key limitations.
First, the study of natural xylitol in people's blood was observational and can only show an association between sugar and alcohol and heart risk. It does not show that xylitol caused a higher incidence of heart attack, stroke, or death.
However, given the totality of the evidence presented in the article, “it is probably reasonable to limit your intake of artificial sweeteners,” Khan said. “Perhaps the answer is not to replace sugar with artificial sweeteners, but to think about higher-quality dietary components, such as vegetables and fruits, as natural sugars.”
Artificial sweeteners shouldn't be difficult to avoid, said Joanne Slavin, PhD, RDN, professor of food science and nutrition at the University of Minnesota-Twin Cities. They are listed in the ingredients list of packaged products.
“Would I say never eat xylitol?” asked Slavin, who had no connection to the study. For some people struggling to reduce sugar in their diet, sugar substitutes are a tool and it all comes down to personal choice, he said.
While Slavin found the study interesting and cause for some concern, he noted that sugar alcohols are expensive and are typically used in very small amounts in sugar-free gum and candy.
Another limitation of the study is that participants whose blood xylitol levels were measured were at high risk for or had documented heart disease, so the results may not apply to healthy people.
Still, many people in the general public share the characteristics of the study participants, Hazen said.
“In middle-aged and older Americans, it's common to have obesity and diabetes or high cholesterol or high blood pressure,” he said.
