What is The Sugar Substitute in Your Protein Bar Might Be Causing Strokes — Here's What the New Research Shows?
You're probably eating erythritol right now without knowing it.
It's in Quest bars, Halo Top ice cream, Built protein bars, most "keto-friendly" packaged foods, and an expanding range of diet sodas. Erythritol is a sugar alcohol — technically a carbohydrate that the body largely doesn't absorb, producing near-zero calories. It tastes remarkably like sugar, doesn't spike blood glucose, and until recently was considered one of the safest sugar substitutes on the market.
Here's why recent research suggests that story is more complicated than the packaging implies.
## What the New Study Found
New data published in early 2026 shows erythritol disrupts brain blood vessel cells — specifically, their ability to dilate properly. The study examined the effect of erythritol on cerebrovascular endothelial cells (the cells lining blood vessels in the brain), finding that at concentrations consistent with regular dietary consumption, erythritol reduced vasodilation capacity.
Why does vasodilation matter? Brain blood vessels need to dilate in response to changing demands — exercise, cognitive load, changes in blood pressure. Impaired vasodilation is a known risk factor for stroke and is associated with conditions like cerebral small vessel disease, which causes approximately 25% of strokes.
This isn't the first erythritol warning. In 2023, a study in Nature Medicine found that higher blood erythritol levels were associated with increased cardiovascular event risk — specifically, platelet aggregation (clotting) in a way that could contribute to heart attacks and strokes. That study was observational (it couldn't prove causation), but it was large: nearly 3,000 patients over three years.
The new 2026 research adds a mechanistic explanation — a potential "how" to accompany the "what."
## The Steelman: What Industry and Some Researchers Say
Before concluding that your protein bar is a stroke risk, the skeptical case deserves serious consideration. Several researchers have pushed back on the 2023 study and its successors.
First, the observational study critique: people who consume a lot of erythritol in the real world may be doing so because they have conditions (obesity, diabetes, metabolic syndrome) that independently elevate cardiovascular risk. The correlation might not be erythritol causing the risk — it might be that high-risk people consume more erythritol-sweetened "healthy" foods.
Second, the dosage question: the 2023 Nature Medicine study used erythritol at concentrations that some researchers argue are higher than typical dietary exposure. The 2026 vasodilation study similarly faces scrutiny on whether the cell concentrations tested reflect what actually reaches brain vasculature after oral consumption and gut absorption.
Third, the comparison point: erythritol is likely safer than sugar (which definitively causes metabolic disease at scale) and may be safer than some alternative sweeteners. The risk comparison is relative, not absolute.
## What This Means in Practice
The honest answer is: we don't have enough evidence to say "erythritol causes strokes" with confidence, but we have enough emerging evidence to say "the assumption that erythritol is completely safe may have been premature."
If you're consuming large amounts of erythritol regularly (multiple servings per day of keto products), the research suggests this warrants attention — particularly if you have existing cardiovascular risk factors. If you have the occasional Quest bar a few times a week, the risk profile is much less clear.
The broader lesson is about the pattern of how food science works. An ingredient gets adopted at scale based on early safety data and a plausible mechanism ("the body doesn't absorb it, so it's inert"). Then as consumption scales up and research depth increases, more nuanced findings emerge. This happened with trans fats (adopted widely, then found to be cardiovascular risks), with several artificial sweeteners, and now potentially with erythritol.
The related science story of the week: a gene therapy research team announced a proof-of-concept for targeting pain signaling at the neural level without opioid mechanisms — a potential future alternative to opioid pain management. It's early-stage research, but it represents a fundamentally different approach to pain than anything currently approved.
Also trending in health science: brief intense exercise (getting genuinely out of breath for a few minutes daily, even just 1-2 minutes) dramatically cuts risk of heart disease, dementia, and diabetes in a study of nearly 100,000 people. The implication is that exercise intensity matters as much as duration — relevant for people who say they "don't have time to exercise."
## Reading Food Labels in 2026
Erythritol appears on ingredient labels as "erythritol" or under the term "sugar alcohol." It's often blended with other sweeteners (monk fruit, stevia, xylitol). Common erythritol-containing products: most keto-certified snack bars, some protein powders, Halo Top and similar low-calorie ice creams, Truvia (the tabletop sweetener), and an expanding range of diet beverages.
The research doesn't warrant panic. It does warrant reading labels with more information than you had before.
Three years from now, erythritol's safety profile will be significantly better understood. Until then, the precautionary approach is to treat it like any food additive where the long-term safety data is still accumulating — moderate consumption rather than unlimited consumption.
Origin
The 2026 erythritol vasodilation study circulated in preprint form in early March and was picked up by ScienceDaily and health media outlets in late March. It builds on the 2023 Nature Medicine study by Stanley Hazen's team at the Cleveland Clinic, which generated significant attention at the time and has been followed closely by cardiovascular researchers.
Timeline
Why Is This Trending Now?
Erythritol is in an enormous number of "healthy" products marketed specifically to health-conscious consumers. The trend hit because it creates a specific, personal concern for millions of people who actively chose erythritol-containing products as healthier alternatives. The 2023 Nature Medicine study planted the seed of concern; the 2026 vasodilation findings gave it a mechanistic explanation that made it more credible and more alarming.
