Q: I’ve noticed that more and more diet and sugar-free food products contain ingredients called sugar alcohols. What are they? And are they any better for you than table sugar?
If you are a regular reader of food packaging, you may have noticed a row under the “total carbohydrate” section of some nutrition facts labels called “sugar alcohol” — and wondered what it means.
Despite what the name might imply, sugar alcohols are neither sugars nor alcohols, said Imashi Fernando, a registered dietitian nutritionist in Seattle. They are a type of carbohydrate that can be added to foods and drinks to make them sweeter without adding the same amounts of calories and carbs as regular sugar. They are not technically artificial sweeteners, Fernando said.
Some sugar alcohols can be found in whole foods. Pineapples, olives, asparagus, sweet potatoes and carrots are natural sources of mannitol; cereals, mushrooms and some fruits and vegetables contain xylitol; and various fruits such as apples, pears, blackberries, peaches and prunes contain sorbitol. But the sugar alcohols often present in packaged products — including sugar-free candies, gums, chocolate, energy bars, cookies, energy drinks, cough syrups, throat lozenges and toothpastes — are synthetically produced.
You can usually spot many sugar alcohols on ingredients lists by the “-ol” at the ends of their names.
The upsides of sugar alcohols
The main draw of sugar alcohols is that they can sweeten foods and drinks without adding many calories and carbohydrates, said Joanne Slavin, a professor of food science and nutrition at the University of Minnesota. Whereas regular table sugar supplies about 4 calories per gram, Slavin said, sugar alcohols provide much less than that — “anywhere from half a calorie to 3 calories per gram.”
They also help keep carbohydrate intake low because they are not completely absorbed through digestion, Fernando said. If the nutrition label of a granola bar says it contains 5 grams of sugar alcohols, for example, you won’t necessarily digest and absorb 5 grams of carbohydrates. Still, sugar alcohols aren’t carb-free, Fernando said — as might be perceived by some, including those on the keto diet, who count net carbs (or only the carbohydrates that their bodies will digest and use). On average, she said, your body will absorb about a third to half of the carbohydrates in sugar alcohols.
If you are someone who needs to monitor blood sugar levels — if you are diabetic, for example — sugar alcohols can be an attractive substitute for sugar since they won’t spike your blood sugar or insulin levels as regular sugar would, Slavin said. But beyond those benefits for blood sugar, there is not enough research on how, or even if, sugar alcohols help diabetic people stay healthy.
Sugar alcohols also don’t cause cavities as regular sugar does, Slavin added. In fact, they can even help prevent them by suppressing cavity-causing bacteria. Xylitol in particular has been shown to be effective, and can be found in mouthwashes, toothpastes and sugar-free gums.
The downsides of sugar alcohols
Fewer calories and carbs are an appealing aspect of sugar alcohols, Slavin said, but there are risks and benefits to consuming them. Many downsides of sugar alcohols have to do with how they are processed in the gut.
Regular sugars are broken down during digestion and then absorbed in the small intestine, said William Chey, a gastroenterologist and professor of medicine at Michigan Medicine. Sugar alcohols, on the other hand, are “very slowly and incompletely broken down in the small intestine,” he said. The small portion that is broken down gets absorbed as usual, he added — but the half to two-thirds of sugar alcohols that remain unabsorbed move on to the large intestine, where they feed your gut bacteria. Bacteria consequently produce gases and short-chain fatty acids, which pull water into your colon and create a laxative effect. Consuming a lot of sugar alcohols, Chey said, can lead to flatulence, bloating, abdominal pain and diarrhea, especially if you have “underlying gastrointestinal conditions like irritable bowel syndrome or inflammatory bowel disease,” he added.
Studies have found that in adults, consuming 20 to 30 grams of sorbitol per day can cause abdominal pain; 100 grams of xylitol can cause diarrhea; and 20 grams or more of mannitol can have a laxative effect. Your tolerance for sugar alcohols will in part depend on how much you weigh: An average adult man who weighs 200 pounds, for instance, will start feeling laxative effects after consuming about 90 grams of erythritol or 2,300 grams of maltitol. One serving of Hershey’s Zero Sugar Chocolate Candy Bars has 16 grams of maltitol, and a pint of Halo Top mint chip ice cream has 18 grams of erythritol.
Sugar alcohols “are a very common cause for gastrointestinal symptoms,” Chey said. “It’s literally something we see every day.”
In fact, the low-FODMAP diet — which is designed to help people soothe digestive distress by eliminating certain types of carbohydrates from their diets — specifically says to avoid sugar alcohols.
If you frequently have digestive issues, Chey said, look at the nutrition labels of all the sweet things you consume, and if you spot sugar alcohols — which “are pretty ubiquitous,” he said — try eliminating them from your diet. This can be a powerful move to explain and relieve gastrointestinal distress.
The bottom line
For most people, eating foods with sugar alcohols won’t be harmful to your health, Fernando said. But every sugar alcohol is a little different, Chey said, and so are the ensuing symptoms.
If you’re just trying to cut down on sugar and reduce your cravings, “sugar-free” foods with sugar alcohols in them are not necessarily the answer, Fernando said, because they will only reinforce your sweet-eating habits and may further fuel future cravings for sugar. To nip that craving in the bud, you must wean yourself off processed sweet foods, she said.
On the other hand, if you need a low-calorie alternative that won’t spike your blood sugar, Slavin said, sugar alcohols are good options. But if you aren’t counting calories or watching your blood sugar, there aren’t many benefits to consuming them. “It’s just a tool in the tool kit, and we shouldn’t overuse them,” Slavin said, adding that, at the end of the day, whole foods are best.