A new study from the University of Colorado Boulder has raised concerns about erythritol, a popular low-calorie sweetener often found in sugar-free foods and drinks.
The research suggests that erythritol may harm the tiny blood vessels in the brain, possibly increasing the risk of stroke or other serious brain-related problems.
Erythritol is a sugar alcohol used in many “sugar-free” or “keto-friendly” products like protein bars, soft drinks, and baked goods.
It tastes sweet—about 60 to 80 percent as sweet as regular sugar—but contains almost no calories and does not raise blood sugar levels, making it especially popular among people with diabetes or those trying to lose weight.
Interestingly, our bodies can also make erythritol naturally during the breakdown of sugar.
Despite its popularity, erythritol has come under closer scrutiny recently.
Large population studies in the United States and Europe have found that people with higher levels of erythritol in their blood also tend to have a greater chance of having heart attacks and strokes.
These connections remained even when researchers accounted for other common health risks like high blood pressure or diabetes. However, scientists had not been able to fully explain how erythritol might cause these health issues—until now.
To investigate this further, the Colorado research team conducted a lab-based study to see how erythritol affects cells that line the tiny blood vessels in the brain.
These blood vessels, called microvascular endothelial cells, play a crucial role in keeping the brain healthy. They control blood flow, protect against damage, and help prevent dangerous blood clots.
The scientists took human brain endothelial cells and exposed them to an amount of erythritol similar to what someone might consume from a single diet drink. They ran several tests to see how the cells responded to this exposure.
The results were concerning. The cells showed about 75% more oxidative stress—this means there were more harmful molecules called free radicals that can damage cells and tissues. To fight this stress, the cells increased the production of certain protective proteins, but this was not enough to undo the damage.
The researchers also found that erythritol affected how well the cells produced nitric oxide, a molecule that helps blood vessels relax and widen. Although the total amount of the enzyme that makes nitric oxide stayed the same, its activity dropped. This is important because if blood vessels can’t relax properly, it can raise the risk of high blood pressure and poor blood flow.
In another part of the study, the scientists looked at the cells’ ability to dissolve clots. They found that erythritol-treated cells released less of a clot-dissolving substance when needed, which could mean a higher chance of harmful clots forming in the brain.
The researchers concluded that erythritol can interfere with several important functions in brain blood vessels—raising oxidative stress, lowering nitric oxide, and reducing the ability to break down clots. All of these problems could, over time, make strokes or other brain-related conditions more likely.
It’s important to note that this study was done in a lab using isolated human cells, not in living people. The exposure was short-term, and we don’t yet know what might happen with long-term use or in the human body. Still, the results match previous findings that linked erythritol to higher stroke risk in people.
Because of these findings, the authors suggest more research is urgently needed. Future studies should test the effects of erythritol in animals and in people over longer periods of time. They also call for clinical studies to explore whether eating or drinking erythritol regularly could have lasting effects on brain and heart health.
In summary, while erythritol may seem like a safer, lower-calorie option to sugar, this new study suggests it may not be as harmless as once thought—especially for brain blood vessels. Until more is known, people who are at risk of stroke or heart disease may want to be cautious with foods and drinks containing this sweetener.
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The research findings can be found in Journal of Applied Physiology.
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