Polyols, often labeled as 'sugar alcohols' on nutritional information panels, are a class of low-calorie carbohydrates used as sugar substitutes. Their use is widespread in the food industry for producing low-sugar and diet-friendly products, leading to frequent confusion about their identity. While they serve a similar purpose to artificial sweeteners by providing a sweet taste without the calories of sugar, their chemical composition, metabolic pathway, and functional properties are fundamentally different. Understanding this distinction is key to making informed dietary choices, particularly for individuals with specific health conditions like diabetes or irritable bowel syndrome (IBS).
What Exactly Are Polyols?
In chemistry, a polyol is an organic compound with multiple hydroxyl (-OH) groups. Though named 'sugar alcohols,' they are neither sugars nor standard alcohol (ethanol). Many polyols occur naturally in fruits and vegetables in small quantities, but for commercial food production, they are typically produced synthetically through a process called hydrogenation of common sugars.
Some of the most common polyols found in commercial food products include:
- Erythritol (E968): Often produced via fermentation, it is almost fully absorbed in the small intestine, resulting in minimal calories and a low risk of digestive issues.
- Xylitol (E967): Found naturally in fibrous plants and berries, it is commonly extracted from corncobs or hardwood trees.
- Sorbitol (E420): Found in many stone fruits and berries, it is commercially produced from corn syrup.
- Maltitol (E965): Produced from maltose, a component of starch.
- Isomalt (E953): A blend of two sugar alcohols, gluco-sorbitol and gluco-mannitol, produced from sucrose.
The Fundamental Difference: Bulk vs. High-Intensity Sweeteners
The most significant distinction between polyols and high-intensity artificial sweeteners lies in their functional roles and caloric content. Polyols are 'bulk' sweeteners, meaning they are used in volumes comparable to sugar to provide not only sweetness but also texture, mouthfeel, and bulk. In contrast, artificial sweeteners are 'high-intensity,' providing a sweet taste hundreds of times more potent than sugar with no calories, and therefore used in minuscule amounts. This difference in function dictates how they are used in food formulation and how the body processes them.
Digestion and Metabolism
Because they are poorly absorbed in the small intestine, most polyols contribute fewer calories than sugar and have a lower impact on blood sugar levels. The unabsorbed portion travels to the large intestine, where it is fermented by gut bacteria. This fermentation process can lead to gastrointestinal side effects like gas, bloating, and diarrhea, especially when consumed in large quantities. Erythritol is an exception, as its nearly complete absorption in the small intestine means it bypasses fermentation and has little-to-no caloric value. High-intensity artificial sweeteners, on the other hand, are typically not metabolized for energy and pass through the body unchanged, so they do not cause the same digestive effects.
Comparing Sweeteners: Polyols vs. Artificial Sweeteners
| Feature | Polyols (Sugar Alcohols) | High-Intensity Artificial Sweeteners |
|---|---|---|
| Examples | Erythritol, Xylitol, Sorbitol, Maltitol | Aspartame, Sucralose, Saccharin, Acesulfame K |
| Source | Found naturally in fruits/vegetables; most are synthetically manufactured | Synthetically produced chemical compounds |
| Calories | Contain fewer calories than sugar (approx. 0-3 kcal/g). Erythritol is near-zero. | Calorie-free. |
| Sweetness | Less sweet than sugar, ranging from 40% to 100% sweetness depending on the type. | Significantly sweeter than sugar (200x to 600x sweeter or more). |
| Digestive Impact | Poorly absorbed, can cause bloating, gas, and laxative effects in excess amounts due to fermentation. | Not digested, typically do not cause gastrointestinal distress unless combined with other components. |
| Food Function | Act as bulk sweeteners, providing volume, texture, and moisture in addition to sweetness. | Primarily provide sweetness without contributing bulk or texture. |
| Impact on Blood Sugar | Have a low glycemic index, causing a minimal rise in blood sugar. | Do not contain carbohydrates, so they do not affect blood sugar levels. |
Uses, Benefits, and Potential Drawbacks
Applications and Health Advantages
Because they replicate many of sugar's functional properties with fewer calories, polyols are a versatile tool for food manufacturers. Their benefits include:
- Dental Health: Unlike sugar, polyols are not readily fermented by oral bacteria, which helps prevent tooth decay. Xylitol, in particular, has been shown to have anti-cavity effects.
- Weight Management: Their lower calorie content per gram helps in creating reduced-calorie products, which can support weight management efforts.
- Blood Sugar Control: Their low glycemic index makes them a valuable sugar substitute for people with diabetes or those looking to manage blood sugar levels.
- Bulking and Texture: They add desirable texture and mouthfeel to products like chewing gum, candies, and baked goods.
The Link to FODMAPs
Many polyols, particularly sorbitol and mannitol, are classified as Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols (FODMAPs). For some individuals, especially those with IBS, these poorly absorbed carbohydrates can trigger digestive symptoms. This makes a low-FODMAP diet a popular strategy for identifying and managing food-related digestive triggers. The amount of polyol that causes discomfort varies widely among individuals, so personal tolerance must be considered.
Reading the Label: Identifying Polyols
Food labeling regulations require polyols to be declared correctly, though this can sometimes be confusing for consumers. In the U.S., they are typically grouped under the term 'sugar alcohols' on the Nutrition Facts label. In the ingredient list, you may find them by their specific name (e.g., Erythritol) or their E-number. It is important to remember that because they are not high-intensity artificial sweeteners, they will not be listed alongside compounds like aspartame or sucralose.
Another key label indicator is the laxative warning. Products containing more than a certain percentage of added polyols are required to carry a statement such as 'Excessive consumption may produce laxative effects'. This warning is a direct result of their unique digestive properties and serves as a signal to consumers to be mindful of their intake.
Conclusion: A Distinct Class of Sweeteners
In conclusion, polyols are not artificial sweeteners. While both are used to reduce sugar content, polyols are a separate class of bulk sweeteners known as sugar alcohols. They differ significantly in their chemical structure, caloric impact, and how the body metabolizes them. Polyols provide valuable functional properties to foods and offer benefits for dental health and blood sugar control. However, their unique digestive pathway also means they can cause gastrointestinal discomfort in sensitive individuals, a side effect not typically associated with high-intensity artificial sweeteners. Understanding this clear distinction is crucial for navigating modern food products and making informed, healthy choices.
For more information on the functional properties and health aspects of polyols, including detailed glycaemic index values, interested readers can refer to resources like the European Association of Polyol Producers website.
