Quick answer: Are sugar alcohols bad for you? Most cause gastrointestinal (GI) discomfort at moderate doses, and recent 2023 and 2024 research links the two most common ones — erythritol and xylitol — to elevated risk of blood clotting, heart attack, and stroke. They are not the harmless sugar swap they were marketed as, and the safest move is to read labels and limit them where possible.
The promise on the label is hard to argue with: zero calories, no spike in blood sugar, often listed as "natural." For two decades, sugar alcohols built an entire category on the idea that you could have the sweetness of sugar without the metabolic cost. Erythritol, xylitol, maltitol, and sorbitol moved out of sugar-free gum and into protein bars, keto desserts, ice cream, and "no sugar added" chocolate. The science has now caught up, and the picture is messier than the packaging suggests. This guide walks through what sugar alcohols actually are, why most of them cause digestive trouble, and what the latest cardiovascular research says about the two that show up most often on labels.
What sugar alcohols are and why they're added to food
Despite the name, sugar alcohols are neither sugar nor the kind of alcohol you drink. They are a class of carbohydrates called polyols, with a chemical structure that sits between a sugar and an alcohol molecule. Some occur naturally in trace amounts in fruits and vegetables, but the versions added to packaged foods are produced industrially, usually by hydrogenating a sugar molecule or by fermenting glucose with yeast.
Manufacturers reach for them because they taste sweet — 50 to 100 percent as sweet as table sugar — without delivering the same calories or blood sugar response. The body absorbs them only partially in the small intestine, which is why they show up on labels as "low calorie" or "no sugar added." That same partial absorption is also the source of nearly every problem with the category. The most common sugar alcohols you will see on a label are erythritol, xylitol, maltitol, sorbitol, mannitol, isomalt, and lactitol.
Why sugar alcohols upset most people's digestion
The mechanism is straightforward. When a sugar alcohol passes through the small intestine without being fully absorbed, it travels into the large intestine, where it pulls in water by osmosis and is fermented by gut bacteria. Both effects produce the symptoms that follow a sugar-free chocolate or low-carb cookie: gas, bloating, cramping, and at higher doses, diarrhea. Sugar alcohols are classified as high-FODMAP (the "P" in FODMAP stands for polyols) and are generally avoided on low-FODMAP plans used to manage irritable bowel syndrome (IBS).
Threshold doses vary by sweetener. Sorbitol and maltitol can trigger discomfort at 10 to 20 grams per sitting, which is well inside the dose used in a single sugar-free candy bar. Erythritol is the most digestively gentle of the group because roughly 90 percent of it is absorbed and excreted in urine without ever reaching the large intestine, but at doses above about 50 grams it too can cause bloating and loose stools.
What 2023 and 2024 research found about cardiovascular risk
For years, digestive side effects were the only well-known downside. That changed in 2023, when researchers at the Cleveland Clinic published a study in Nature Medicine that followed roughly 4,000 patients undergoing cardiac evaluation and found that those with the highest blood erythritol levels were about twice as likely to suffer a major adverse cardiovascular event (heart attack, stroke, or death) over the following three years. Follow-up laboratory work showed that adding erythritol to blood at concentrations seen after a typical sugar-free serving directly increased platelet activation and clot formation.
A 2024 human intervention study from the same group built on that finding. After a single dose of erythritol equivalent to one sugar-free soda or muffin, blood levels in 20 healthy adults rose more than a thousandfold and stayed elevated for hours, with measurable changes in platelet behavior. A separate 2024 paper reported a similar pattern for xylitol. None of this proves causation, and the U.S. Food and Drug Administration (FDA) still classifies erythritol as Generally Recognized as Safe (GRAS). But the consistency of the signal has pushed cardiovascular researchers to call for the safety of these sweeteners to be re-evaluated.
Sugar alcohols at a glance
| Sweetener | Sweetness vs. sugar | Glycemic index | GI tolerance threshold | Notable concern |
|---|---|---|---|---|
| Erythritol | 60–80% | ~1 | ~50 g per sitting | Linked to platelet activation and cardiovascular risk |
| Xylitol | ~100% | ~13 | ~30 g per sitting | Linked to cardiovascular risk; toxic to dogs |
| Maltitol | 75–90% | ~52 | ~20 g per sitting | Glycemic load close to table sugar |
| Sorbitol | ~60% | ~9 | ~10 g per sitting | Strong laxative effect at modest doses |
| Mannitol | 50–70% | ~0 | ~20 g per sitting | Common digestive side effects |
| Isomalt | 45–65% | ~9 | ~20 g per sitting | Common in sugar-free hard candy; bloating |
What to choose instead
Two practical responses follow from the research. The first is to read labels carefully. Sugar alcohols are required to be listed in the ingredients but often hide inside vague phrases like "sugar-free sweetener blend." Look for the names — erythritol, xylitol, maltitol, sorbitol, mannitol, isomalt, lactitol — anywhere in the ingredient list. A "no sugar alcohols" claim on the front of a package is now a meaningful signal in a category where most low-sugar products use them.
The second is to reframe the goal. The cleanest path is not to chase a zero-calorie sugar substitute but to choose foods sweetened with a real, minimally refined source in modest quantity. Coconut sugar, maple syrup, and honey carry a glycemic load below table sugar and contain trace minerals, and in a well-formulated snack the absolute amount of sweetener is usually small enough that the metabolic difference is negligible.
This is part of why a brand like Marmels skips sugar alcohols entirely, sweetening 62 percent single-origin organic cacao with organic coconut sugar instead — a real, minimally refined sweetener with a lower glycemic load and no risk of digestive upset.
Frequently Asked Questions
Are sugar alcohols safe for people with diabetes?
Most sugar alcohols have a low glycemic impact and are widely used in products marketed to people with diabetes, with the notable exception of maltitol, which has a glycemic index near 52 (close to table sugar at 60). The newer cardiovascular research is particularly relevant here, because people with diabetes already carry elevated cardiac risk and the populations in the recent erythritol research were also high-risk.
Which sugar alcohol causes the most stomach problems?
Sorbitol and maltitol are the most likely to trigger gas, bloating, and diarrhea, often at doses as low as 10 to 20 grams per serving. Erythritol is the most digestively tolerated because the body absorbs and excretes most of it without fermentation, although it carries the strongest signal in the recent cardiovascular research.
Are sugar alcohols natural?
Some occur naturally in trace amounts in fruits, vegetables, and fermented foods, but the versions added to packaged foods are produced industrially — usually by hydrogenating a sugar molecule or by fermenting glucose with yeast. A "natural" label reflects a regulatory definition rather than how the ingredient was traditionally sourced or used in food.
Do sugar alcohols count as carbohydrates on the nutrition label?
Yes. Sugar alcohols are listed under total carbohydrates and itemized on a separate "sugar alcohols" line. They are usually subtracted from total carbs to estimate "net carbs" for low-carb diets because most are only partially absorbed, but the math understates how much of the dose still reaches the gut and contributes to digestive symptoms.
Is erythritol still considered safe?
The FDA continues to classify erythritol as Generally Recognized as Safe (GRAS) based on its earlier review. The recent cardiovascular research is association-based and mechanistic rather than from large randomized trials, which is the standard the agency typically waits for before changing a designation. Several cardiovascular researchers have called for a re-evaluation, and consumers who want to be cautious can simply check labels and choose products that don't contain it.
Sugar alcohols looked like the cleanest sugar substitute on paper, and for two decades they were treated that way. The newest research has not made them off-limits, but it has made the math harder to ignore. The cleanest move stays the simplest one: choose foods sweetened with real, minimally refined ingredients in modest amounts. For more on the choices behind our bars, see our science page.
