A key component of following a ketogenic, or keto, diet is reducing your sugar intake, which is necessary for your body to enter ketosis, a state in which your body burns fat rather than sugar for energy. However, that doesn’t mean you can’t enjoy sweet-tasting foods. Sugar alcohols are sweeteners that have tastes and textures similar to those of sugar, but fewer calories and a less significant effect on blood sugar levels. As a result, they can be a satisfying option for individuals looking to reduce their sugar intake, such as those following a keto diet.
This article explains whether sugar alcohols are keto-friendly, as well as which ones may be better options for you, with a focus on isomalt.
What are Sugar Alcohols?
Sugar alcohols, also known as polyols, are a specific type of carbohydrate. They occur naturally in some fruits and vegetables. However, most are commercially manufactured in a lab. While there are many types of sugar alcohols, common ones you may see on food labels include:
- Erythritol: Often made by fermenting the glucose found in cornstarch, erythritol has 70% of the sweetness of sugar but 5% of the calories.
- Isomalt: Isomalt is a mixture of two sugar alcohols - mannitol and sorbitol. Providing 50% fewer calories than sugar, it’s most commonly used to make sugar-free hard candies and is about 50% as sweet.
- Maltitol: Maltitol is processed from the sugar maltose. It’s 90% as sweet as sugar with almost half the calories.
- Sorbitol: Commercially produced from glucose, sorbitol is 60% as sweet as sugar with about 60% of the calories.
- Xylitol: One of the most common sugar alcohols, xylitol is as sweet as regular sugar but has 40% fewer calories.
Due to their low calorie contents, sugar alcohols are frequently used to sweeten sugar-free or diet products like gum, yogurts, ice cream, coffee creamers, salad dressings, and protein bars and shakes.
How Sugar Alcohols Affect Blood Sugar
When you eat sugar, your body breaks it down into smaller molecules. These molecules are then absorbed into your bloodstream, which causes your blood sugar levels to rise.
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In contrast, your body cannot fully break down and absorb carbs from sugar alcohols. As a result, they cause a much smaller rise in blood sugar levels. One way to compare the effects of these sweeteners is their glycemic index (GI), which is a measure of how quickly foods can raise your blood sugar.
Here are the GI values of common sugar alcohols:
- Erythritol: 0
- Isomalt: 2
- Maltitol: 35-52
- Sorbitol: 9
- Xylitol: 7-13
Overall, most sugar alcohols have negligible effects on your blood sugar levels. To compare, white table sugar (sucrose) has a glycemic index of 65.
Sugar Alcohols and the Keto Diet
Sugar intake is limited on a keto diet, as eating it causes your blood sugar levels to rise. This is an issue, as raised blood sugar levels can make it difficult for your body to remain in ketosis, which is key for reaping the benefits of the keto diet. Given that sugar alcohols have a much less significant effect on blood sugar levels, they’re commonly found in keto-friendly products.
Furthermore, since they aren’t fully digestible, keto dieters often subtract the sugar alcohols and fiber from the total number of carbs in a food item. The resulting number is referred to as net carbs.
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Still, due to the variation in GIs of different types of sugar alcohols, some are better for the keto diet than others. Erythritol is a good keto-friendly option, as it has a glycemic index of 0 and works well in both cooking and baking. Plus, due to its small particle size, erythritol tends to be better tolerated than other sugar alcohols.
Still, xylitol, sorbitol, and isomalt are all suitable on a keto diet. You may simply want to scale back your intake if you notice any gastrointestinal side effects. One sugar alcohol that appears to be less keto-friendly is maltitol. Maltitol has a lower GI than sugar. However, with a GI of up to 52, it’s likely to have a more significant effect on your blood sugar levels than other sugar alcohols. As such, if you’re on a keto diet, you may want to limit your intake of maltitol and choose a sugar alternative with a lower GI.
Technically, most sugar alcohols should be counted as regular carbohydrates and kept to a minimum on the ketogenic and modified Atkins diets (MAD). Although they may affect blood glucose differently in different people, most sugar alcohols have the potential of raising blood sugar. The exception to this rule is erythritol since it is metabolized differently and does not affect blood glucose.
Isomalt: A Closer Look
Isomalt is a sugar alcohol derived from sucrose, typically sourced from sugar beets. Through a process called hydrogenation, it becomes a sugar alcohol that mimics the sweetness and structure of sugar with fewer calories and a lower glycemic response. It is a mixture of two sugar alcohols - mannitol and sorbitol. Providing 50% fewer calories than sugar, it’s most commonly used to make sugar-free hard candies and is about 50% as sweet.
While isomalt is low in calories and glycemic impact, it is partially absorbed by the body, so it should be consumed in moderation on a strict keto diet. It’s often included in keto-friendly candy and gum due to its sugar-like texture and stability.
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Applications of Isomalt
Isomalt is a versatile ingredient used in various applications:
- Beverage: Isomalt can be used as a low-calorie ingredient in beverages, such as fruit-flavored drinks or sugar-free sodas. It is ideal for those who need to watch their sugar intake for diabetic, weight loss, or even tooth sensitivity reasons.
- Bakery/Confectionery: Isomalt holds really well in heat and humidity, making it ideal for decorative cake toppers, sugar-free (hard and chewy) candies, and chewing gum. It can also be used as a glazing, bulking, and anti-caking agent in ready-to-eat cereals, fruit spreads, and even with frozen foods such as ice cream, fish, and meat products. Professional bakers often rely on isomalt sweetener to achieve intricate sugar decorations and lasting clarity in molded shapes.
- Nutraceutical: Isomalt is considered an anti-caking and bulking agent and can also be used in multivitamin and mineral supplements, pan-coated tablets, lozenges, and cough syrups. Its stability and clean sweetness make it a preferred choice in functional health products where taste, texture, and performance all matter.
Is Isomalt Safe?
Yes, isomalt is considered safe for all age groups and is commonly used in sugar-free confections, including those marketed for children. It’s also recognized as safe by global regulatory bodies and approved for use in a variety of food systems.
Potential Side Effects of Sugar Alcohols
When consumed in normal amounts through food, sugar alcohols are considered safe for most individuals. However, they do have the potential to cause digestive issues, especially in larger amounts. Side effects like bloating, nausea, and diarrhea have been observed when intake of sugar alcohols exceeds 35-40 grams per day.
Additionally, individuals with irritable bowel syndrome (IBS) may experience negative side effects with any amount of sugar alcohols. As a result, if you have IBS, you may want to avoid sugar alcohols completely.
Your body can’t fully digest sugar alcohols, which can lead to some unpleasant GI symptoms when eaten in larger quantities - and they usually happen pretty soon after you eat them.
In a 2006 British study, researchers gave participants doses of sugar or one of two types of sugar alcohols (xylitol and erythritol). Those who took xylitol reported bloating, gas, upset stomach, and diarrhea. Erythritol appeared to have milder effects on the stomach, only increasing nausea and gas when consumed in large doses.
Sugar alcohols may also have a laxative effect because your stomach can’t absorb them, which can cause them to linger in your intestines and ferment. This effect is most common in children and in adults.
Emerging Research on Sugar Alcohols and Health Risks
While sugar alcohols have long been considered a safe addition to your diet in moderation, new research is showing that elevated levels of sugar alcohols can be dangerous to your health.
Circulating levels of both xylitol and erythritol have been shown to be associated with an increased risk for “major adverse cardiovascular events.” That includes a heightened risk for heart attack, stroke, and even death.
Studies with blood, platelets, and non-human models all point to erythritol and xylitol enhancing blood clotting risks (what happens in a heart attack or stroke). The concern is that eating foods with these sugar alcohols may put you at a higher risk for heart attack and stroke.
High levels of xylitol and erythritol can send your platelets into overdrive. Platelets are the components in your blood that allow it to clot. Clotting is a good thing if you have an open wound. It keeps you from bleeding out. But when your blood clots inside your body, it’s a recipe for a medical emergency - like a heart attack or stroke.
It doesn’t take much either. For example, just one scoop of keto-friendly ice cream contains up to 30 grams of xylitol. Research suggests that’s enough to agitate your platelets and make them more likely to form clots. And the increased risk lasts about four to six hours (or until you eat more xylitol-containing foods.) When you eat foods containing erythritol, the risk can remain for several days.
More research needs to be done to understand what the effects are of other sugar alcohols. But based on what we see from xylitol and erythritol, it’s fair to say that sugar alcohols should warrant caution. These compounds are in foods that are typically marketed to people with diabetes, who already have an increased risk for major heart events. And the sugar alcohols in their diets may inadvertently be adding to that risk.
Identifying Sugar Alcohols on Food Labels
Just as sugar lurks behind different terms on food labels, sugar alcohols also have many names. When you see one of these products on a label, here’s what you’re getting:
- Xylitol: is about as sweet as sugar. It comes from wheat straw and some cereals. On an industrial scale, it’s produced from wood materials or by microbial fermentation. It’s often found in sugar-free desserts and candies. Also frequently found in diabetic candies. Notably, you’ll also find it in some oral care products, like toothpaste and mouthwash because it helps prevent dental carries. The dangers associated with xylitol are related to eating it in large quantities. So, it’s not going to cause negative effects in your dental care (swish and spit) routine.
- Erythritol: is 60% to 80% as sweet as sugar. While it can be found in small quantities in things like pears, soy sauce, and watermelon, on an industrial scale, it’s made by yeast fermentation of corn or wheat starch. One of the fastest-growing sugar substitutes in the food industry, ingesting it as a sugar substitute can raise blood levels more than a 1,000 fold and take days before returning back to baseline levels.
- Isomalt: is about 45% to 65% as sweet as sugar. It comes from beet sugar.
- Lactitol: provides about 40% of the sweetness of sugar. Manufacturers make it from milk.
- Maltitol: is about 75% as sweet as sugar and is made from corn, wheat, and potatoes, and catalytic hydrogenation.
- Mannitol: is 50% to 70% as sweet as sugar. Naturally, it occurs in carrots, olives, and asparagus. While some manufacturers make it from seaweed, much is made from hydrogenation of fructose at high temperatures and pressure.
- Sorbitol: is about half as sweet as sugar. Naturally, it’s found in apples and pears, but industrially, it’s made from potato starch.
Food and Drug Administration (FDA) doesn’t require food companies to list sugar alcohols on their ingredient lists. Aside from reading the ingredients on food labels, you can identify products that may contain sugar alcohols by looking for processed foods that say they’re:
- Keto-safe.
- Diabetes-safe.
- Sugar-free, no sugar, or low sugar.
- Artificially sweetened.
- Naturally sweetened or sweetened with natural compounds.
- Low-calorie or calorie-free.
Another dead giveaway that a product includes sugar alcohols is a label that says, “Excessive consumption can cause a laxative effect.” The FDA requires this language on any product that contains added sorbitol or mannitol.