What are Polyols and How Are They Metabolized?
Polyols are a class of carbohydrates that are neither true sugars nor alcohols, despite their common name 'sugar alcohols'. They are found naturally in small quantities in fruits and vegetables but are often manufactured from sugars and starches for commercial use. Common examples include erythritol, xylitol, sorbitol, and maltitol.
The key to understanding how polyols affect blood glucose lies in their metabolism. Unlike regular sugars, which are quickly and fully absorbed, polyols are only partially absorbed in the small intestine. The portion that isn't absorbed travels to the large intestine, where it can be fermented by gut bacteria, which is why excessive consumption can lead to digestive issues like gas, bloating, and diarrhea. This incomplete absorption is the reason they provide fewer calories and have a reduced impact on blood sugar compared to sucrose.
The Glycemic Impact of Different Polyols
Not all polyols are created equal when it comes to their effect on blood glucose. The glycemic index (GI), a ranking of carbohydrates based on their effect on blood sugar levels, varies significantly among different polyol types. For reference, pure glucose has a GI of 100.
Low-Impact Polyols
- Erythritol: Considered the best option for managing blood sugar, erythritol has a GI of 0 and is not metabolized into glucose. It passes through the body without affecting blood sugar levels at all.
- Xylitol, Sorbitol, and Isomalt: These polyols are absorbed more slowly and in smaller amounts than sugar, resulting in a much lower GI. Their GIs are typically in the single digits, meaning they cause a very minimal increase in blood glucose.
Moderate-Impact Polyols
- Maltitol: While still considered a low-glycemic food, maltitol has a higher glycemic index than other common polyols. Some sources cite its GI as high as 36, which is still significantly lower than sugar but can cause a more noticeable rise in blood glucose, especially in large quantities.
Polyols and Blood Glucose: A Comparative Look
To highlight the differences, here is a comparison table of common polyols based on their impact on blood glucose and potential side effects.
| Polyol Type | Glycemic Index (GI) | Calories per Gram | Common Use | Laxative Effect? |
|---|---|---|---|---|
| Erythritol | 0 | ~0.2 | Confectionery, drinks | Rare, mild |
| Xylitol | 7-8 | ~2.4 | Gum, toothpaste | Moderate |
| Sorbitol | 9 | ~2.6 | Diet foods, sugar-free sweets | Moderate |
| Maltitol | ~36 | ~2.1 | Sugar-free chocolate, baked goods | Moderate to strong |
Counting Carbohydrates with Polyols
For individuals with diabetes, understanding how to count carbohydrates from polyols is essential. Because they are not fully absorbed, the carbohydrate impact is not equal to the total grams listed on a nutrition label.
- Erythritol: Since it has no effect on blood glucose, it is typically considered to have zero net carbs and can be disregarded in carbohydrate counts.
- Other Polyols (Xylitol, Sorbitol, etc.): Many healthcare professionals recommend counting half of the listed polyol grams toward your total carbohydrate intake. This is an estimation, and it's always best to monitor your own blood sugar levels to see how your body responds.
Lists of polyol-containing foods
- Sugar-free candy and chocolates: Often sweetened with maltitol, which has a higher GI.
- Sugar-free chewing gum: Commonly uses xylitol or sorbitol.
- Baked goods: Some low-carb or keto-friendly baked goods use erythritol and other polyols.
- Protein bars: Many brands use polyols to reduce sugar content, but labels must be checked as the type and quantity can vary significantly.
- Toothpaste and mouthwash: Xylitol is frequently added to help prevent tooth decay.
Potential Side Effects of Polyol Consumption
While polyols offer a benefit by reducing sugar intake, they are not without potential downsides. The unabsorbed portion that reaches the large intestine is fermented by gut bacteria. This process can lead to gastrointestinal distress, especially when consumed in large quantities, with symptoms including:
- Bloating and abdominal pain
- Excessive gas (flatulence)
- Diarrhea, as polyols can have a laxative effect
Sensitivity to these effects can vary greatly among individuals. For those with irritable bowel syndrome (IBS) or FODMAP sensitivities, some polyols are known triggers. Food products containing more than 10% added polyols in some regions are required to carry a warning that excessive consumption may produce laxative effects.
Conclusion: Making an Informed Choice
In conclusion, polyols do affect blood glucose, but the impact is generally much lower and slower than that of regular sugar. The key takeaway is that the effect is not uniform and depends heavily on the specific polyol consumed. Erythritol stands out for having a negligible effect, making it the most blood sugar-friendly option. Other polyols like maltitol have a more significant impact and should be consumed with more caution, especially for those managing diabetes. As with any dietary choice, moderation is crucial, and monitoring your body's individual response is the most reliable strategy. When in doubt, consult a healthcare professional, especially if you are managing a condition like diabetes. Calorie Control Council offers more information on polyols and their uses.
