Two research efforts, two years and two continents apart, arrived at almost the same number. In 2024, a Cleveland Clinic team published peer-reviewed evidence in the European Heart Journal that people with the highest blood levels of xylitol — a sugar alcohol used to sweeten sugar-free gum, candy, and baked goods — had 1.57 times the risk of a heart attack, stroke, or death within 3 years compared with people with the lowest levels (adjusted hazard ratio 1.57, 95% CI 1.12–2.21, P<.01). In August 2026, a separate team presented new data at the European Society of Cardiology's annual congress showing the same pattern, in a much larger sample, over much longer follow-up: 57% higher risk.
The 2024 study didn't stop at correlation. Researchers first flagged xylitol in a discovery cohort (n = 1157) of people undergoing heart evaluations, then confirmed the signal in an independent validation cohort (n = 2149) using a more precise blood test. To test whether xylitol could actually cause harm, not just track alongside it, they ran a small human experiment: 10 healthy volunteers drank a xylitol-sweetened beverage, and every single one showed increased platelet activity afterward — the blood-clotting response measured in the lab jumped in all 10 people. Separate lab and animal experiments showed xylitol made blood clot faster and more easily.
The 2026 congress data adds scale, not yet peer review. Presented by Dr. Marco Witkowski (now at Charité, Berlin — first author on the 2024 paper too), this new analysis pooled 17,710 people from two long-running cohorts: the Canadian Longitudinal Study on Aging and the UK's EPIC-Norfolk study. People with xylitol levels in the highest quarter had a 57% higher risk of a major cardiovascular event over 6 years of follow-up in the Canadian cohort, and an 18% higher risk over 30 years in the European cohort — both after adjusting for age, sex, smoking, cholesterol, diabetes, and blood pressure. The risk rose in step with xylitol levels across the full range, not just at the extremes. This work has been presented at a scientific congress but has not yet gone through peer review, which typically follows within a few months.
Who's behind this, and who's paying for it, matters. The 2026 presentation's funding came entirely from public research bodies — the Canada First Research Excellence Fund, a Quebec research fund, the Corona Foundation, and the Berlin Institute of Health — and Dr. Witkowski reports no conflicts of interest. The 2024 peer-reviewed paper is a more mixed picture: it was funded by NIH and German research grants, but its senior author, Dr. Stanley Hazen, discloses royalty payments and consulting income tied to cardiovascular diagnostic patents from Cleveland HeartLab (a Quest Diagnostics subsidiary) and Procter & Gamble, plus consulting and research funding from Zehna Therapeutics, Pfizer, and Roche. None of those ties are to a sweetener manufacturer, and they don't change the underlying lab data, but they're worth knowing.
What this doesn't prove. Both studies are observational at their core — they show that people with more xylitol in their blood have more cardiovascular events, not that xylitol is definitely the cause. The 2024 team addressed that gap with lab and animal experiments showing a believable mechanism (heightened platelet clotting), which strengthens the case, but it isn't the same as a large randomized trial telling people to avoid xylitol and tracking what happens.
Bottom line. Two independent research groups, using different populations and different follow-up periods, both found that people with the highest blood levels of xylitol had roughly 20–60% higher long-term cardiovascular risk than those with the lowest levels, and a small experiment showed xylitol directly increases blood clotting activity in humans. It's not proof that occasional sugar-free gum causes heart attacks, but it's a large enough, well-funded enough signal that regulators and shoppers alike are likely to hear more about it as the newer data works through peer review.
Medical note. This article is intended for general educational purposes and should not be considered personal medical advice.