Sugar Alcohols: Are They Compatible with the Medical Ketogenic Diet?
If you are following or considering a medical ketogenic diet or modified Atkins diet (MAD) for the management of intractable epilepsy, you may have heard talk about sugar alcohols and whether they are compatible with the diet. In today’s blog post, ketogenic dietitian Stacey Bessone will tell us more about sugar alcohols and what role they play with the medical ketogenic diets.
Sugar alcohols are a specific type of carbohydrate called “polyols”. Sugar alcohols are naturally occurring in fruits and vegetables and often added to foods as a reduced-calorie alternative to sugar. Some common sugar alcohols you may see in food ingredient lists include:
It’s important to be aware that some sugar alcohols may cause some people to experience bloating, gas and diarrhea, even when consumed in small amounts.
Sugar Alcohols & Glycemic Index
Interestingly, most sugar alcohols are incompletely absorbed in the small intestine, so they do not raise blood sugar the same way as sucrose (table sugar). However, since they are partially absorbed, they may affect blood glucose levels to some degree. This can be observed by looking at the glycemic indexes of sugar alcohols compared to sugar. Glycemic index is a measure of the increase in blood glucose when a food is digested and absorbed. It is based on a numeric scale from zero to 100, where the glycemic index of glucose (a type of sugar you get from foods and the form that your body uses for energy) is 100. The glycemic index of sucrose (table sugar) is around 65, whereas the glycemic indexes of the main sugar alcohols are between 0 and 45. Therefore, sugar alcohols may raise your blood glucose, although not as much as sugars like sucrose and glucose.
One specific type of sugar alcohol, Erythritol, is metabolized differently than other sugar alcohols. Erythritol is fully absorbed in the small intestine and excreted in the urine unchanged, so it does not affect blood glucose levels like other sugar alcohols. As you can see in the chart above, the glycemic index of erythritol is zero.
Calories in Sugar Alcohols
Sugar alcohols provide fewer calories per gram compared to regular carbohydrates. Sugar alcohols are therefore often used as a reduced-calorie alternative to sugar.
Sugar Alcohols, Erythritol, and the Ketogenic Diet
So, are sugar alcohols allowed on the medical ketogenic diet and modified Atkins diet (MAD)? Technically, most sugar alcohols should be counted as regular carbohydrates and kept to a minimum on the medical 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. I generally tell my medical ketogenic diet and modified Atkins diet (MAD) patients that when reading a food label for carbohydrate content, erythritol is the only sugar alcohol that can be deducted from total carbohydrate content. I also tell my patients that sugar alcohol can only be deducted from the total carbohydrate amount if erythritol is the only sugar alcohol used in a product. When other sugar alcohols are used in addition to erythritol, the sugar alcohol content cannot be deducted, so I tell my patients to read the food label’s ingredient list carefully.
Speak to Your Healthcare Provider
Each dietitian has his/her own protocols, so while I allow my medical keto patients to deduct erythritol but no other sugar alcohols from total carbohydrate content, your provider may have different recommendations. As always, it’s important to speak to your dietitian about which foods and ingredients are allowed for your unique diet.
Are Sugar Alcohols Keto-Friendly?
A key part of following a ketogenic, or keto, diet is reducing your sugar intake.
This 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.
Sugar alcohols 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 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
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
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 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
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.
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 alcohol completely
Sugar alcohols are low calorie sweeteners that generally have little to no effect on your blood sugar levels. As a result, they’re a popular keto-friendly option for sweetening foods and beverages.
Just keep in mind that some may be better choices than others.
For example, maltitol has a much greater effect on blood sugar levels than erythritol, which has a GI of 0.
The next time you’re looking to add sweetener to your coffee or make homemade keto-friendly protein bars, try using a sugar alcohol like erythritol or xylitol.
Just be sure to consume these sweeteners in moderation to avoid any potential digestive distress.