How Sugar Alcohols Might Be Messing With Your Gut

As we become more aware of the health risks associated with added sugars, substitute sweeteners have never been more popular. Some—like aspartame (NutraSweet and Equal), saccharin (Sweet n’ Low), sucralose (Splenda), luo han guo (Monkfruit in the Raw), and stevia—you might recognize by their brand s, but sugar alcohols, another alternative, tend to fly under the radar.

Sugar alcohols—also known as polyols—are carbohydrates that share chemical characteristics with both sugars and alcohols, hence their moniker, Janice Dada, MPH, RDN, a certified intuitive eating counselor based in California, tells SELF. (To be clear, they don’t contain actual booze, in case you were wondering.) Like other sugar substitutes, sugar alcohols are a “type of low-calorie sweetener” that help “reduce calories and sugar intake,” Ashlee Bobrick, MS, RDN, a registered dietitian nutritionist at the Ohio State University Wexner Medical Center, tells SELF. They’re “pretty commonly used in lots of different types of foods,” Dada says.

While sugar alcohols have a few significant health benefits (which we’ll delve into shortly), they also have an infamous downside: digestive side effects like gas, bloating, cramping, and diarrhea. Naturally, not everyone will be noticeably affected—“Some people are more sensitive to it than others,” Dada says—but it’s definitely an established concern. Below, we’ll discuss what sugar alcohols are, where you can find them, why they can trigger GI distress, who is most at risk, and how you can keep yourself from falling into their trap.

Sugar alcohols deviate from actual sugar (as in sucrose, a.k.a. white table sugar) in a few key ways. Here are some of the main differences:

• They’re lower in calories: Sugar alcohols contain significantly fewer calories than sugar (at 1.5 to three calories per gram versus four calories per gram, according to Yale New Haven Health), making them a smarter choice for weight control.
• They’re less likely to spike blood sugar: Sugar alcohols don’t cause a “rapid increase in blood glucose,” Bobrick says, though, as carbohydrates, they will still raise it slightly. Because of their minimal impact, Bobrick says, they’re especially suitable for people with diabetes (and often marketed to this demographic, Dada adds).
• They’re better for dental health: Sugar alcohols don’t promote cavity formation because they don’t react with plaque bacteria in the mouth. In fact, some may even help prevent tooth decay. One particular type, xylitol, stands out from the crowd for its ability to beat back harmful microbes.
• They’re less sweet: Sugar alcohols are anywhere from 25% to 100% as sweet as sugar, so on the whole, they tend to have a more muted effect on flavor.

Sugar alcohols are also distinct from other sugar substitutes, including artificial sweeteners (like Splenda, Equal, NutraSweet, and Sweet n’ Low) and novel sweeteners (like luo han guo and stevia). By comparison, artificial sweeteners have no calories, don’t cause any increase in blood sugar whatsoever, and are actually significantly sweeter than sugar (to the tune of 200 to 700 times), though Bobrick notes they have a less “natural taste.”

While sugar alcohols occur naturally in a variety of fruits and vegetables (albeit in small amounts), the bulk of your intake probably consists of those that are commercially produced to serve as additives in sugar-free and reduced-sugar sweet treats. Candy, ice cream, chewing gum, fruit spreads, and baked goods are all common sources, Dada says.

That said, sugar alcohols can also crop up in food items you might think of as healthy (or at least health-ier), like protein bars, according to Dada. “I've seen them in large amounts in some of these products,” she says. Perhaps even more surprisingly, sugar alcohols aren’t limited to food items alone, either: Thanks to their beneficial effects on dental health, they’re a staple in oral hygiene products like mouthwash and toothpaste.

Even though we’ve referred to them as a monolith thus far, many different sugar alcohols exist, all of which have their own relative sweetness (compared to sugar), effect on blood sugar, caloric value, and source. Most have names ending in the suffix “-ol”—a handy little tell that helps make them easy to spot on an ingredients list. Here are a few examples, according to Yale New Haven Health:

• Mannitol: Occurs naturally in asparagus, olives, carrots, pineapples, and sweet potatoes.
• Sorbitol: Occurs naturally in fruits and vegetables. Often found in sugar-free chewing gum and candy.
• Xylitol (a.k.a. “wood sugar”): Occurs naturally in straw, corncobs, fruits, vegetables, cereals, and mushrooms. Found in chewing gum.
• Lactitol: Often found in chocolate, chewing gum, sugar-free ice cream, baked goods, sugar-reduced preserves, and hard and soft candies.
• Isomalt: Often found in toffee, hard candies, cough drops, and lollipops.
• Maltitol: Found in ice cream, chewing gum, baked goods, sugar-free hard candies, and chocolate-flavored desserts.
• Hydrogenated starch hydrolysates (HSH): Found in confections, baked goods, and mouthwashes.
• Erythritol: Occurs naturally in fruits like melons, pears, and grapes as well as fermented foods like cheese and soy sauce (and also happens to be produced in your body!), according to the Mayo Clinic. Per a 2017 article in the scientific journal Applied Microbiology and Biotechnology, erythritol is often found in candy, chocolate, chewing gum, beverages, and baked goods.

If you’ve ever eaten a pint of Halo Top ice cream or a few Quest bars (yes, both of those contain sugar alcohols, FYI!) and immediately found yourself fighting for your life in the bathroom, you probably want to know why. It all comes down to how sugar alcohols are metabolized: Unlike regular sugar, they’re physically challenging to process, according to Bobrick.

Your body “cannot fully digest or absorb them in the small intestine,” Bobrick explains, so instead, they head on to the next stage of the digestive journey more or less intact. “Once they reach the large intestine,” she says, “they draw in water and are fermented by gut bacteria, leading to gas, bloating, and diarrhea.”

The GI impact can be so pronounced that products containing the sugar alcohols sorbitol and mannitol are federally mandated to feature a warning on the nutrition label: “Excess consumption may have a laxative effect.” Mannitol in particular has a tendency to linger in your intestines, often triggering bloating and diarrhea as a result, according to Yale New Haven Health.

While sugar alcohols can trigger digestive irritation in anyone, some demographics are more sensitive, especially people with preexisting digestive health conditions, according to Dada. “Certainly anybody who has IBS would potentially be at a bigger risk,” for example, she says. Same for IBS’s sister condition, SIBO, as well as celiac disease and IBD, according to Bobrick. (Yep—contrary to what you might think, IBD is a totally distinct condition from IBS!)

For similar reasons, people who have had GI surgery (like bariatric surgery) should also steer clear of sugar alcohols in large amounts, according to Bobrick. Ditto those following a low-FODMAP diet, which restricts or eliminates common problem carbs and then slowly reintroduces them in a bid to identify digestive triggers, Dada says. Sometimes, in fact, “people will figure out that they're susceptible to these GI disturbances” through that process, she says.

Finally, folks prone to cardiovascular issues may want to avoid one sugar alcohol in particular, according to Dada: erythritol. Some research has linked erythritol to an increased risk of blood clots, itself a risk factor for heart disease and stroke—something “to be paying attention to” if you might be more susceptible, she says.

Checking the nutrition label for sugar alcohols is an excellent place to start. Just keep in mind that not all labels will be completely transparent: Per the FDA, manufacturers are only required to list sugar alcohols if a statement is made on the packaging about the health effects of sugar or sugar alcohols (e.g., a claim like “sugar-free”), though some may choose to provide this information anyway.

If sugar alcohols are listed (you can find them under the “Total Carbohydrates” heading, as shown in this FDA image), you can then make an informed buying decision based on the amount and the corresponding likelihood of side effects. “Most people are going to be affected by something like 15 grams,” Dada says, but those who have a potential sensitivity might have a lower bar to clear, so she recommends a better-safe-than-sorry approach: “If it’s more than five grams in a product [per serving], I’d say be cautious if you’re not sure.” By that standard, both Halo Top ice cream—which clocks in at five to six grams per serving—and Quest bars—which clock in at six grams or more per serving—would be off-limits, for example.

Even if you’re not particularly sensitive to sugar alcohols, try to stick to that 15-gram daily cutoff for your own comfort, Dada says. “Otherwise we'd probably expect some digestive distress”—and we don’t know about you, but we’d prefer to avoid that at all costs. If you slip up, however, it’s not the end of the world: Staying hydrated and eating something else may help counter the effects, according to Bobrick—and, in fact, consistently consuming sugar alcohols may actually boost your tolerance over time.

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