Are Sugar Alcohols the Culprit of Your Digestive Woes?

Registered dietitian Elaine Magee's curiosity got the best of her. While writing about sugar alcohols – a category of low-calorie sweeteners – for her job, she decided to taste them in the form of sugar-free chocolates.

One chocolate down, no problem. Two chocolates down, risky. Three chocolates down, bring on the gas, bloating, cramping and subsequent gastrointestinal distress.

"Once you go through it, it's like, 'OK, I'm never having more than one again," says Magee, a San Francisco-based author of 25 books including "Tell Me What to Eat If I Have Diabetes" and "Tell Me What to Eat If I Have Irritable Bowel Syndrome." The upside? "It sure does motivate you to have portion control," she says with a laugh.

To be fair to the chocolates, Magee has irritable bowel syndrome, which already makes her digestive system more sensitive than most. Sugar alcohols can sit just fine in many people's bellies, she points out, since how the "system ferments and digests" differs for everyone. 

Here's what to know before testing them yourself:

What are sugar alcohols?

Don't judge a substance by its name: Sugar alcohols are neither sugar nor alcohol, says Roger Clemens, adjunct professor at the University of Southern California's International Center for Regulatory Science. No buzz or hangover, he confirms. Rather, they are called such because, chemically, they look a bit like sugar and a bit like alcohol. Technically, they're carbohydrates.

Sugar alcohols, alsocalled polyols, are found naturally in plants, but can be made synthetically by adding hydrogen molecules to certain sugars. You'll find them in your chewing gum, sugar-free candy, protein bars, toothpaste and plenty of processed foods under names including sorbitol, lactitol, xylitol, mannitol and typically anything else with an "ol" ending, Clemens says.

They're different from artificial sweeteners – think aspartame and sucralose – not only in structure, but also in caloric content. While artificial sweeteners tend to be calorie-free, sugar alcohols have 0.2 to 2.7 calories per gram, according to a 2015 paper in European Food Research and Technology. That's still fewer than your everyday table sugar, which has roughly 4 calories per gram. Sugar alcohols are also used more often in solid foods than in liquids or as an option in sugar packets at thecoffee bar. ​"They work best in some types of bar-like products and confections," Clemens says.

Sugar alcohols are regulated by the U.S. Food and Drug Administration, which must approve them before they're used as food additives. Some sugar alcohols, however, can forgo this process if scientists have already recognized them as safe​. You can find them on food labels included in the "total carbohydrates" count, but manufacturers aren't required to list them explicitly unless the product is so-called "sugar-free," the International Food Information Council Foundation reports. 

The Pros

Want the sweetness of sugar without the calories? Sugar alcohols can be your friend, says Joy Dubost​, a registered dietitian in the District of Columbia and spokeswoman for the Academy of Nutrition and Dietetics. "They have a role in one's diet, particularly if you're trying to manage your overall consumption of sugar or added sugar," she says. They can also help manage diabetes, since they don't affect blood sugar as much as other carbohydrates, according to the American Diabetes Association. People with or at risk for heart disease or obesity can benefit too, suggests a 2003 paper in Nutrition Research Reviews.

Sugar alcohols also have a leg up on sugar when it comes to your mouth – they won't cause tooth decay, which is why you see them in plenty of "sugar-free" chewing gums. In fact, some sugar alcohols may ​even protect teeth against plaque and other dental problems, research suggests. 

For some consumers, sugar alcohols might taste better than artificial sweeteners. ​Some varieties also have a pleasing cooling effect (which is also why they're popular in gum), Clemens says. And for food manufacturers, the ingredients are popular choices to add bulk and texture, prevent browning during heating and retain moisture, according to the International Food Information Council Foundation. 

The main takeaways? "They're safe, low in calories and don't promote dental ​[decay]," he says. Even the Academy of Nutrition and Dietetics says they're safe to enjoy, so long as you do so in combination with a healthy, balanced diet and in line with your health goals. 

The Cons

As Magee can attest, sugar alcohols aren't all sweet. For some people, they can lead to digestive issues – namely, gas, bloating and diarrhea – and for most people, they can lead to such issues if consumed in excess.​ That's why the FDA requires products that add more than 50 grams (or nearly 2 ounces) of sorbitol – a sugar alcohol in a variety of products including candies, jam and baked goods – to a person's ​diet to print a warning saying, "Excess consumption may have a laxative effect." Other sugar alcohols have similar requirements. But not to worry, Clemens says: Most products contain only a few grams of sugar alcohols. And, as with any food, "if you abuse it or overconsume it or increase your exposure to it, your likelihood of having adverse effects [on your digestion] goes up," Clemens says.

Why? ​"They're not completely absorbed or digested; they pass through the small intestine and are ​fermented in the large intestine, and that fermentation can cause gas" – if not something worse, Dubost explains. On the flip side, you have their less-digestible nature to thank for their low caloric value: Since your body can't entirely absorb them, it can't use them much for energy, either. ​ 

Even if your stomach can handle them, sugar alcohols aren't for everyone. Despite their ubiquity in low-carb, low-sugar protein bars, shakes and powders, most athletes need carbohydrates to fuel their sport and may be turning to sugar alcohols unnecessarily, says Britt Burton-Freeman​, ​director of the Center for Nutrition Research at the Illinois Institute of Technology.​ "It depends on what's the end-goal here," she says. "If the end-goal is to lose weight or cut back on carbohydrate calories, then these make a nice option."

The Bottom Line

Take a cue from Magee and do some experimenting. You may feel uncomfortable after sucking on too many cough drops with manitol, for instance, but fine after a scoop of reduced-sugar ice cream made with lactitol. You might get gassy after a few pieces of gum on an empty stomach, but have no trouble when chewing a post-meal stick. "Some of this is trial and error and finding out if you react to them," Dubost says.

If the side effects of sugar alcohols outweigh their benefits for you, like ​Magee, "there are plenty of ways to reduce caloric intake," says Burton-Freeman, who recommends cutting back on portions if you want to enjoy products made with, say, real fruit (and hence​, real sugar).

McGee's go-to strategy is eating "the real thing" mindfully. So instead of reaching for the sugar-free chocolates and winding up at the toilet, she has a single Dove chocolate, closes her eyes and lets it melt on her tongue. "If you eat it mindfully," she says. "You're satisfied with one."