Sugar alcohols such as erythritol, xylitol, sorbitol and maltitol are in sugar-free gum, keto snacks, protein bars, toothpaste and many gummy vitamins. Also called polyols, they have fewer calories than sugar and a smaller effect on blood sugar. They have two well-known downsides: gas and diarrhea in larger amounts, and real danger to dogs. Since 2023 there has been a third worry: headlines linking erythritol and xylitol to heart attacks and strokes.
This guide explains what sugar alcohols are, how much it takes to upset your stomach, how they affect blood sugar and "net carbs," and what the heart studies actually show, including what they do not show. It also covers teeth, IBS and the sugar alcohols hiding in supplements.
The short version
- Sugar alcohols are only partly absorbed. That explains their fewer calories, smaller blood sugar rise and digestive side effects. Erythritol is the exception: most of it (about 60 to 90 percent in small studies) is absorbed and passed unchanged in urine, so it has essentially no calories and is the easiest on the stomach.
- Diarrhea depends on the dose and the type. In adults, 20 to 35 grams of erythritol in a drink caused no significant symptoms, while 35 to 50 grams of xylitol caused watery stools. Sorbitol caused gas at 10 grams in a small study.
- Blood sugar: on the glycemic index (GI, a measure of how much a food raises blood sugar, where glucose is 100), erythritol scores 0 and xylitol 13, while maltitol (35) is closer to a slow sugar, so a "sugar-free" maltitol chocolate still adds carbohydrate.
- The heart headlines are a reason for caution, not proof of harm. Higher blood levels of erythritol and xylitol were linked to heart events in people already being checked for heart disease (and erythritol to heart-related deaths in some broader groups), and a single large dose (30 grams in the erythritol study) made platelets (the blood cells that form clots) more reactive in two small studies. But the body makes these compounds itself, genetic studies disagree, and no trial has tested whether eating them causes heart attacks.
- Who should be careful: if you have heart disease, a history of blood clots, or diabetes, it is reasonable to avoid large single servings until better data arrive and to discuss it with your doctor. See what the heart studies show.
- Xylitol can kill dogs. Keep xylitol gum, chewable vitamins, gummies and toothpaste away from pets. If your dog eats any, call a veterinarian or animal poison control right away.
- Check supplement labels. Sugar-free gummies can contain several grams of maltitol, isomalt or sorbitol per serving.
What sugar alcohols are: the common ones
Sugar alcohols, also called polyols, are carbohydrates whose chemical structure resembles both sugar and alcohol, though they contain no ethanol. Some occur naturally in small amounts: sorbitol in certain fruits, mannitol in some vegetables, and erythritol in grapes, pears and fermented foods such as soy sauce and cheese. Commercial versions are made from starches, birch or corn (xylitol is sometimes sold as "birch sugar"), or by fermentation.
Because the small intestine absorbs them poorly, much of what you eat reaches the large intestine, where it draws in water and is fermented by bacteria. For most sugar alcohols, that one fact explains all three everyday effects: fewer calories, a smaller blood sugar rise, and gas or diarrhea in larger amounts. Erythritol is the exception: most of it is absorbed and then passed unchanged in urine.
| Sugar alcohol | Calories per gram | Glycemic index (GI) |
|---|---|---|
| Erythritol | 0 | 0 |
| Mannitol | 1.6 | 0 |
| Isomalt | 2.0 | 9 |
| Lactitol | 2.0 | 6 |
| Maltitol | 2.1 | 35 |
| Xylitol | 2.4 | 13 |
| Sorbitol | 2.6 | 9 |
| Table sugar | 4 | 65 |
Table sugar is shown for comparison. Calorie values are from US labeling rules (21 CFR 101.9); glycemic index values (glucose = 100) are from a 2003 review. The EU uses 2.4 calories per gram for all polyols except erythritol, which counts as 0.
Is allulose a sugar alcohol? No. Allulose is a rare sugar that the FDA lets companies leave out of "Total Sugars" and "Added Sugars" and count at 0.4 calories per gram. Stevia, monk fruit and sucralose are not sugar alcohols either; they are high-intensity sweeteners used in tiny amounts. See our guide to sweeteners in supplements for those.
Net carbs, keto and food labels
On a US Nutrition Facts label, sugar alcohols count toward "Total Carbohydrate" but not "Total Sugars." Listing "Sugar Alcohol" grams is voluntary unless the package makes a claim about sugar or sugar alcohols, and the label may use the specific name (for example, xylitol) only if just one sugar alcohol is present. The same voluntary rule applies to Supplement Facts panels.
"Net carbs" is not an FDA term. The FDA has not defined it, and companies calculate it in different ways, often by subtracting fiber and all sugar alcohols from total carbohydrate. That treats maltitol, which raises blood sugar somewhat and has about half the calories of sugar, the same as erythritol, which has neither. If you follow a keto or low-carb diet and count net carbs, check the ingredient list to see which sugar alcohol a product uses: erythritol adds essentially nothing, while a maltitol-sweetened bar counts for more than its net-carb number suggests.
Side effects: gas, diarrhea and how much is too much
The laxative effect is the best-documented side effect, and it depends on both the type and the amount:
- Erythritol is the best tolerated. In a double-blind study of 64 young adults, 20 and 35 grams of erythritol in water caused no significant symptoms; 50 grams increased nausea and stomach rumbling. A Japanese study found the largest single dose that did not cause diarrhea was about 0.46 grams per kilogram of body weight in men and 0.68 in women.
- Xylitol caused watery stools at 35 and 50 grams in the same young-adult study.
- Sorbitol is among the harshest. In a small study of 7 people, 10 grams caused gas and bloating, and 20 grams caused cramps and diarrhea in most. Doctors have reported chronic diarrhea and severe weight loss traced to sorbitol in sugar-free chewing gum.
- Maltitol, isomalt and lactitol vary. In milk chocolate eaten by young adults, 30 grams of maltitol caused only mild gas and no laxative effect, while 30 grams of lactitol significantly increased all symptoms; in another study lactitol caused diarrhea at a lower dose per kilogram than xylitol. Foods and drinks differ, and mixing several polyols adds up.
Regulators reflect this. US rules require the warning "Excess consumption may have a laxative effect" on foods that could lead someone to eat 50 grams of sorbitol or 20 grams of mannitol a day, and the EU requires a similar warning on foods with more than 10 percent added polyols. Europe's food safety agency set an acceptable daily intake (the amount considered safe to eat every day) for erythritol of 0.5 grams per kilogram of body weight, about 35 grams for a 70 kilogram adult (our arithmetic), based on its laxative effect.
Children are not more sensitive per kilogram of body weight, according to a trial in 184 children aged 4 to 6, but because they are smaller they reach the threshold sooner: diarrhea and other significant symptoms increased at 20 and 25 grams of erythritol in a drink, with no increase in diarrhea or severe symptoms at 15 grams (stools were somewhat softer for the first day). People who eat sugar alcohols regularly may adapt somewhat over time.
Sugar alcohols, IBS and FODMAPs
FODMAPs are fermentable oligosaccharides, disaccharides, monosaccharides and polyols: carbohydrates that are poorly absorbed and fermented by gut bacteria, and that trigger symptoms in many people with irritable bowel syndrome (IBS). Sorbitol and mannitol are the "P" (polyols). In a Monash University trial, 10 grams of sorbitol or mannitol increased symptoms in people with IBS but not in healthy volunteers. In a 2024 study of 117 people with IBS, among those who improved on a low-FODMAP diet and were then blindly challenged with single FODMAPs, mannitol brought symptoms back in 54 percent, one of the two most common triggers (sorbitol, at 23 percent, was no more common a trigger than the glucose control, at 26 percent).
Monash, which developed the low-FODMAP diet, advises avoiding foods with added sorbitol, mannitol, isomalt, maltitol, lactitol and xylitol during the elimination phase. Erythritol is not on that list, but its place on a low-FODMAP diet is not formally settled. Monash also notes that some people with constipation-predominant IBS may find the laxative effect of polyols useful. See our low-FODMAP diet guide and the IBS supplement guide.
Do sugar alcohols raise blood sugar?
Mostly very little, but it depends on which one. In small studies, erythritol did not raise blood sugar or insulin, and xylitol raised them only slightly. Maltitol has the highest glycemic index of the sugar alcohols in the table above (35, compared with 65 for table sugar; hydrogenated starch hydrolysates are similar at 39), and one study found that while maltitol solutions had a low insulin response, maltitol chocolate still produced a high one.
For people with diabetes, swapping sugar for erythritol or xylitol lowers the sugar load. Products sweetened mainly with maltitol, often labeled "sugar free" or "low net carb," still contain digestible carbohydrate, so they are not interchangeable. In a 5-week trial of 42 adults with obesity, 36 grams of erythritol or 24 grams of xylitol a day did not change glucose tolerance.
Do erythritol and xylitol raise heart attack risk?
What the studies found. In 2023, Cleveland Clinic researchers measured erythritol in the blood of people being evaluated for heart disease in the US and Europe. Those with the highest blood erythritol had about 1.8 and 2.2 times (one figure for each group) the 3-year risk of heart attack, stroke or death compared with those with the lowest levels. A 2024 study found a similar link for xylitol (about 1.6 times the risk, highest third versus lowest third, in one US group of patients). Links have also appeared in people without known heart disease. In a US study of 4,006 older adults, higher blood erythritol was linked to hospitalization for heart failure, death from cardiovascular disease and death from any cause (though, unlike its breakdown product erythronate, not to coronary heart disease or stroke). At a 2026 heart conference, researchers reported a similar xylitol link in two general-population groups (presented, not yet published in a journal). In lab and mouse experiments, these compounds made platelets, the cells that form clots, more reactive. In two small studies, each giving a sweetened drink to 10 healthy volunteers, 30 grams of erythritol raised blood erythritol more than 1,000-fold, a xylitol drink (30 grams, according to later commentary) sharply raised blood xylitol, and both increased platelet responses measured 30 minutes later.
Why that is not proof of harm:
- They measured blood levels, not what people ate. The body makes erythritol from glucose, and blood levels are higher in people with high blood sugar, obesity and insulin resistance. In a 2-year weight-loss trial, people whose blood erythritol fell the most also had the biggest improvements in insulin resistance and in estimated heart risk. So a high level may mark poor metabolic health rather than cause heart problems.
- Older blood samples tell a similar story. In Finnish male smokers whose blood was drawn in 1985 to 1993, before erythritol was common in foods, higher levels were still linked to death from cardiovascular disease and from cancer. In US nurses, the erythritol link with heart disease was no longer significant after accounting for diabetes, although a link for mannitol and sorbitol (measured together) remained.
- Genetic studies disagree. These studies, called Mendelian randomization, act as a natural experiment: they compare people born with gene variants linked to higher blood erythritol. Of four such studies, one found no support for a link with coronary disease, while three reported links with coronary disease or stroke, ranging from tiny to modest. These studies reflect lifelong blood levels set by the body's own metabolism, not erythritol in the diet, and one of the teams cautioned against reading its result as proof that eating erythritol causes stroke.
- The platelet studies were tiny. They had 10 volunteers per sweetener and no placebo arm (the erythritol study compared a 30 gram glucose drink, which did not have the same effect). Each tested a single 30 gram dose, with one measurement 30 minutes later, so they cannot show whether the effect lasts or leads to clots. We found no independent replication.
- No trial has tested outcomes. We found no randomized trial of any sugar alcohol with heart attack, stroke or death as the outcome, and the authors themselves say their cohort studies "can only show association, and not causation," although they argue that their lab and animal experiments point to a real causal effect.
Ties matter on both sides. One review questioning the findings was coauthored by a researcher paid by the sweetener company Amyris to review the erythritol literature, and a critical letter on xylitol was coauthored by the founder of a pharmaceutical company. The Calorie Control Council, a sweetener industry group, argues that 30 grams at once is not a typical serving; the researchers counter that it is about what is in one can of sweetened drink or a pint of keto ice cream. The Cleveland Clinic team's senior author reports patents and royalties in heart disease diagnostics, and the disclosures list no ties to sweetener makers. The researchers, for their part, fairly note that long-term safety studies are needed.
Europe's food safety agency, reviewing the 2023 study before the human platelet studies appeared, concluded that the evidence "does not demonstrate a causal relationship" between eating erythritol and heart disease, and set its erythritol limit on the laxative effect.
Who should be careful. The amount in a piece of gum, toothpaste or a gummy vitamin is far below the 30 gram study dose (our arithmetic). If you have heart disease, a history of blood clots, or diabetes, it is reasonable to avoid large single servings until better data arrive, such as a can of erythritol-sweetened drink or a pint of keto ice cream at once (the researchers compare these to the study dose), and to discuss it with your doctor. Our erythritol and xylitol pages list the individual studies.
Xylitol for teeth and ear infections
Mouth bacteria cannot readily ferment sugar alcohols, and the FDA allows sugar-free foods sweetened with them to say they "do not promote tooth decay." That claim is about replacing sugar, not about actively healing teeth. Evidence that xylitol does more than simply replace sugar is weak. A Cochrane review (a systematic review that pools the available trials) found low-quality evidence, from two studies by one research group, that a fluoride toothpaste with 10 percent xylitol may reduce cavities in children's permanent teeth by about 13 percent compared with fluoride alone over about 3 years. It found not enough evidence to judge other xylitol products such as syrups, lozenges or tablets. In a 3-year trial in 485 Estonian schoolchildren, children given erythritol candies developed fewer cavities than those given xylitol or sorbitol candies.
For ear infections, a Cochrane review found moderate-quality evidence that xylitol, given several times a day, reduced ear infections in healthy Finnish children in daycare (from about 30 to 22 percent). But a US trial in ear-infection-prone children given xylitol syrup three times a day, and a small Canadian trial, found no benefit.
Xylitol is dangerous for dogs
- In dogs, xylitol triggers a large insulin release. The FDA warns that dangerously low blood sugar can occur within 10 to 60 minutes and that serious effects may not appear in some cases for up to 12 to 24 hours. The ASPCA and veterinary studies also report liver damage in dogs.
- The FDA warns that a dog eating a pack of sugarless gum could die, and veterinarians have not established a dose that is reliably safe. If your dog eats something containing xylitol, call a veterinarian or animal poison control right away.
- The FDA lists sugar-free gum, mints, some peanut butters, baked goods, toothpaste, chewable vitamins and dietary supplements among products that may contain xylitol, sometimes labeled "birch sugar." Use pet toothpaste for pets, never human toothpaste.
Sugar alcohols in gummies and supplements
Sugar alcohols are common in sugar-free gummies, chewables, lozenges, protein powders and drink mixes, and in liquid medicines. Examples from the NIH Dietary Supplement Label Database show the range: a sugar-free biotin gummy with 5 grams of sugar alcohols (maltitol and isomalt) per two-gummy serving, a fiber gummy with sorbitol, and a chewable vitamin C with sorbitol and xylitol.
A few grams per serving rarely matters on its own, but doubling the dose or combining several sugar-free products adds up. If you are sensitive to sugar alcohols or follow a low-FODMAP diet:
- Read the "other ingredients" list for sorbitol, mannitol, maltitol, isomalt, lactitol and xylitol; the first one listed is present in the largest amount.
- Do not assume "sugar free" means carbohydrate free or calorie free.
- Look for the "Excess consumption may have a laxative effect" warning.
- Store xylitol-containing supplements where dogs cannot reach them.
If you are fasting, gummies sweetened with sugar alcohols still contain carbohydrate; see do supplements break a fast?
Frequently asked questions
Are sugar alcohols bad for you?
For most people they are a reasonable sugar replacement in normal amounts. They have fewer calories than sugar, a smaller effect on blood sugar and do not promote tooth decay. The main downsides are gas and diarrhea at larger doses, symptoms in many people with IBS, and serious danger to dogs from xylitol. Studies linking erythritol and xylitol to heart problems are associations, not proof of harm. If you have heart disease, a history of blood clots or diabetes, it is reasonable to avoid large single servings until better data arrive.
Does erythritol cause heart attacks or strokes?
That has not been shown. People with the highest blood erythritol had about twice the 3-year risk of heart attack, stroke or death in studies of patients already being evaluated for heart disease, and a 30 gram dose made platelets more reactive in a small study. But the body makes erythritol itself, levels rise with high blood sugar and weight, genetic studies disagree, and no trial has tested whether eating it causes heart events.
Is xylitol bad for your heart?
A 2024 study linked higher blood xylitol to heart events in people being evaluated for heart disease, and a xylitol drink (30 grams, according to later commentary) increased platelet responses in 10 volunteers. These findings need replication in larger, controlled studies. The small amounts in gum or toothpaste are far below the study dose.
Is erythritol safe? What are its side effects?
Its main documented side effect is digestive. In adults, 20 and 35 grams in a drink caused no significant symptoms, while 50 grams increased nausea and stomach rumbling. Europe's food safety agency set an acceptable daily intake of 0.5 grams per kilogram of body weight, based on the laxative effect. Studies linking higher blood erythritol to heart events show an association, not proof that eating it causes harm.
What are the side effects of xylitol?
Gas, bloating and diarrhea at larger doses: in a study of young adults, 35 and 50 grams caused watery stools. Monash University advises avoiding added xylitol during the elimination phase of a low-FODMAP diet. A 2024 study linked higher blood xylitol to heart events, which is an association, not proof of harm.
How much sugar alcohol causes diarrhea?
It depends on the type. In adults, 20 to 35 grams of erythritol in a drink caused no significant symptoms, while 35 to 50 grams of xylitol caused watery stools. Sorbitol caused gas at 10 grams and diarrhea at 20 grams in a small study. US labels must warn of a laxative effect when daily intake could reach 50 grams of sorbitol or 20 grams of mannitol.
Which sugar alcohol is easiest on the stomach?
Erythritol. Most of it (about 60 to 90 percent in small studies) is absorbed and passed unchanged in urine, and gut bacteria do not appear to ferment the part that reaches the colon. Sorbitol, mannitol and lactitol are among the most likely to cause gas and diarrhea.
Do sugar alcohols raise blood sugar?
Erythritol does not, xylitol only slightly, and maltitol more, with a glycemic index of 35 compared with 65 for table sugar. Maltitol-sweetened sugar-free sweets still contain digestible carbohydrate.
Do sugar alcohols count toward net carbs?
The FDA has not defined net carbs, and companies calculate it differently, often subtracting all sugar alcohols from total carbohydrate. That overstates the benefit for maltitol and sorbitol, which are partly digested. On US labels, sugar alcohols count toward Total Carbohydrate but not Total Sugars.
Are sugar alcohols OK if you have IBS?
Many people with IBS react to sorbitol and mannitol, which are FODMAPs. Monash University advises avoiding added sorbitol, mannitol, isomalt, maltitol, lactitol and xylitol during the elimination phase of a low-FODMAP diet. Erythritol is not on that list, but its place on a low-FODMAP diet is not formally settled.
Why is xylitol dangerous for dogs?
In dogs, xylitol causes a large insulin release that can drop blood sugar dangerously within 10 to 60 minutes, and it can damage the liver. Veterinarians have not established a dose that is reliably safe. Keep xylitol gum, toothpaste, chewable vitamins and gummies out of reach, and call a veterinarian or animal poison control right away if your dog eats any.
Are sugar alcohols OK on a keto diet?
Erythritol fits a keto or low-carb diet best: it has essentially no calories and did not raise blood sugar or insulin in small studies. Maltitol is a poorer fit: it has about half the calories of sugar and a glycemic index of 35, so subtracting it to calculate net carbs overstates the savings. Check the ingredient list, not just the net carb number.
Is xylitol gum or toothpaste safe?
For people, the amounts are small: a piece of gum or a dab of toothpaste is far below the 30 gram dose used in the heart studies. A Cochrane review found low-quality evidence, from two studies by one research group, that a fluoride toothpaste with 10 percent xylitol may reduce cavities in children's permanent teeth by about 13 percent compared with fluoride alone.
What are the most common sugar alcohols?
Erythritol, xylitol, sorbitol, maltitol, mannitol, isomalt and lactitol. On ingredient lists, all of these except isomalt end in -itol. Allulose, stevia, monk fruit and sucralose are not sugar alcohols.
Is allulose a sugar alcohol?
No. Allulose is a rare sugar. The FDA lets companies leave it out of Total Sugars and Added Sugars on labels and count it at 0.4 calories per gram.
The bottom line
Sugar alcohols are useful sugar replacements with fewer calories, a smaller blood sugar effect and no tendency to cause cavities. Their main everyday downside is digestive: erythritol is best tolerated, while sorbitol, mannitol and xylitol cause gas and diarrhea at lower doses, and some, especially mannitol and sorbitol, can trigger IBS symptoms. Maltitol-sweetened "sugar-free" foods still count as carbohydrate.
The heart headlines come from blood-level associations, partly reflecting the body's own production, plus two tiny platelet studies at a large dose. That justifies caution with large servings for people at high heart or clotting risk, not alarm about gum or toothpaste. And whatever you decide for yourself, keep xylitol away from dogs.