Sugar alcohols are low-calorie sweeteners that your body only partially absorbs, which means they raise blood sugar less than regular sugar, contain fewer calories, and don’t feed the bacteria that cause cavities. They’re found in sugar-free gum, candy, protein bars, ice cream, and many “no sugar added” products. But they come with trade-offs, including digestive side effects and, for one type, emerging concerns about heart health.
How Sugar Alcohols Affect Blood Sugar
Sugar alcohols break down slowly in your gut, and your body only absorbs a portion of their carbohydrates. This keeps your blood sugar and insulin levels from spiking the way regular sugar does. That slower, blunted response is what makes them a practical sugar substitute for people managing diabetes or trying to reduce their glycemic load.
The degree of absorption varies by type. Erythritol, for example, is absorbed into the bloodstream but provides almost zero calories because your body excretes it largely unchanged. Sorbitol and xylitol are partially fermented in the large intestine, delivering roughly 40 to 60 percent of the calories of table sugar. Maltitol sits at the higher end and can still cause a moderate blood sugar rise, so it’s the least favorable option if blood sugar control is your main goal.
Why They’re Better for Your Teeth
Regular sugar feeds the oral bacteria (especially Streptococcus mutans) that produce acid and cause cavities. Sugar alcohols flip that equation. Most dental plaque bacteria can’t ferment sugar alcohols, so they don’t generate the acid that erodes enamel. Xylitol goes a step further: it actively interferes with the growth of cavity-causing bacteria, which is why it’s the sugar alcohol most commonly used in dental gum and lozenges.
This isn’t a minor perk. The cavity-prevention effect of xylitol is well established enough that dentists routinely recommend xylitol gum as part of an oral hygiene routine, particularly for people prone to tooth decay.
Digestive Side Effects and Tolerance Limits
The most common complaint about sugar alcohols is what happens in your gut. Because they’re only partially absorbed, the undigested portion travels to the large intestine, where bacteria ferment it and produce gas. The result: bloating, cramping, and diarrhea, sometimes referred to as the “laxative effect” listed on sugar-free candy packages.
How much it takes to cause problems depends on the type. Sorbitol is one of the least tolerated. Consuming as little as 20 grams per day (roughly the amount in a handful of sugar-free gum pieces) can cause diarrhea significant enough to lead to unintentional weight loss or, in extreme cases, hospitalization. Xylitol has a wider safe range, generally 20 to 70 grams per day, though one study found that a single 50-gram dose dissolved in water caused bloating and diarrhea in 70 percent of participants. Erythritol is the gentlest on the stomach because most of it is absorbed before reaching the colon.
Your tolerance tends to improve over time. If you’re new to sugar alcohols, starting with small amounts and increasing gradually gives your gut bacteria a chance to adapt. Spreading your intake across the day rather than consuming a large amount at once also helps.
The Erythritol Heart Health Concern
Erythritol, long considered the most benign sugar alcohol, came under scrutiny in 2023 and 2024 after research linked high blood levels of it to cardiovascular risk. A study published in the American Heart Association’s journal found that fasting plasma erythritol levels were associated with increased risk of heart attack, stroke, or death over a three-year follow-up period in both U.S. and European cohorts.
The mechanism appears to involve blood clotting. When healthy volunteers consumed 30 grams of erythritol (a realistic amount from processed foods and beverages), their blood plasma concentrations of erythritol spiked more than 1,000-fold, and their platelets became significantly more reactive to clotting signals. In practical terms, this means erythritol may make blood more prone to clotting in the hours after consumption.
This research is still being weighed by the broader scientific community, and it doesn’t mean occasional erythritol use is dangerous. But for people already at elevated cardiovascular risk, it’s worth paying attention to how much erythritol is in the products they consume regularly. Many “keto” and “zero sugar” products use erythritol as their primary sweetener in substantial amounts.
Calorie Content Compared to Sugar
Sugar alcohols contain fewer calories than table sugar, but they’re not calorie-free (with one exception). Table sugar provides 4 calories per gram. Here’s how common sugar alcohols compare:
- Erythritol: 0 to 0.2 calories per gram
- Xylitol: 2.4 calories per gram
- Sorbitol: 2.6 calories per gram
- Maltitol: 2.1 calories per gram
This means most sugar alcohols deliver roughly half to two-thirds the calories of sugar. If you’re eating a protein bar sweetened with maltitol and assuming the sugar alcohol calories “don’t count,” you’re still getting a meaningful calorie contribution. Net carb labels on packaging sometimes subtract all sugar alcohol grams, which can be misleading for higher-impact types like maltitol.
How to Spot Them on Labels
Under FDA rules, sugar alcohols don’t have to appear on a nutrition label unless the product makes a claim about sugar content or sugar alcohols. When they are listed, you’ll see them grouped under “Sugar Alcohol” as a sub-line beneath total carbohydrates. If the product contains only one type, the label can use the specific name (xylitol, sorbitol, erythritol) instead of the generic term.
In the ingredients list, look for names ending in “-ol”: sorbitol, mannitol, maltitol, xylitol, erythritol, isomalt, lactitol, and hydrogenated starch hydrolysates. They’re especially common in sugar-free gum, mints, chocolates, ice cream, baked goods, and cough drops.
Xylitol Is Toxic to Dogs
One critical safety issue that catches many pet owners off guard: xylitol is extremely dangerous for dogs. In most mammals, xylitol has no significant effect on insulin, but dogs are different. Even small amounts trigger a rapid, massive insulin release that can drop a dog’s blood sugar to life-threatening levels within 10 to 60 minutes. Doses above roughly 100 mg per kilogram of body weight are enough to cause hypoglycemia, and higher doses can cause liver failure.
For a 20-pound dog, that threshold could be reached by a single piece of xylitol-sweetened gum, depending on the brand. Peanut butter, gummy vitamins, baked goods, and toothpaste are all common household sources. If your dog ingests anything containing xylitol, it’s an emergency that requires immediate veterinary treatment.