The Chemical Makeup of Sugar Alcohols
Despite their name, sugar alcohols are neither sugars nor alcoholic beverages. Chemically, they are carbohydrates derived from sugars (like glucose or xylose) where the aldehyde or ketone group has been replaced with a hydroxyl group through a process called hydrogenation. This structural modification prevents them from being completely absorbed and metabolized by the body in the same way as sugar. Because they contain multiple hydroxyl groups, they are also known as polyols. These polyols are found naturally in small quantities in fruits and vegetables, but the added sugar alcohols found in most processed foods are produced on an industrial scale.
Common Types of Added Sugar Alcohols
The food industry utilizes a variety of added sugar alcohols, each with unique characteristics related to sweetness, caloric content, and digestive tolerance. The most common types you'll find on ingredient lists often end with the suffix “-itol”.
- Xylitol: Found naturally in many fruits and vegetables, it has a sweetness comparable to sugar but with fewer calories. It is widely used in sugar-free gum and dental products for its oral health benefits.
- Erythritol: This polyol has nearly zero calories and is well-tolerated by the digestive system compared to most other sugar alcohols because it is largely absorbed in the small intestine and excreted in urine. It has a clean, sugar-like taste.
- Sorbitol: About 60% as sweet as sugar and found naturally in fruits like apples and pears. It's often used in sugar-free candies and chewing gum.
- Maltitol: With a taste and texture remarkably similar to sugar, maltitol is about 75-90% as sweet and commonly used in sugar-free chocolates and hard candies.
- Mannitol: Approximately 50-70% as sweet as sugar, mannitol is found in pineapples and other plants. It is often used as a dusting powder and in pharmaceuticals due to its low hygroscopicity.
- Isomalt: This sugar alcohol is derived from beet sugar and is less sweet than table sugar. It is used in hard candies because it resists breaking down at high temperatures and absorbs little water.
Key Health Benefits and Considerations
Dental Health
One of the most significant benefits of added sugar alcohols is their positive effect on dental health. Unlike sugar, they are not easily fermented by oral bacteria, which means they do not contribute to tooth decay. Some, like xylitol, actively inhibit the growth of Streptococcus mutans, the bacteria responsible for cavities. For this reason, xylitol is a frequent ingredient in sugar-free gum and toothpaste.
Glycemic Impact and Calories
Sugar alcohols offer a way to reduce both sugar and calorie intake. Because they are not fully absorbed by the body, they contain fewer calories per gram than regular sugar, which has 4 calories per gram. Their effect on blood sugar levels is also much lower and slower, making them a suitable option for people managing diabetes. Erythritol, in particular, has a minimal impact on blood glucose and insulin levels.
Potential Side Effects and Safety
Digestive Discomfort
The most common side effect of consuming large amounts of sugar alcohols is gastrointestinal distress, including gas, bloating, and diarrhea. This happens because the unabsorbed portion of the polyol travels to the large intestine, where it is fermented by gut bacteria. Sorbitol and mannitol are known to have a more potent laxative effect than erythritol, which is generally well-tolerated. Products containing significant amounts of polyols may carry a warning about excessive consumption causing a laxative effect.
Important Warning for Pet Owners
For humans, xylitol is safe, but it is extremely toxic to dogs. Even small amounts can cause a rapid and dangerous drop in blood sugar, and in severe cases, liver failure. Pet owners should store products containing xylitol safely away from their animals.
Cardiovascular Health
Some observational studies have suggested a potential link between high levels of the sugar alcohol erythritol and an increased risk of cardiovascular events, such as heart attack and stroke, particularly in individuals with pre-existing risk factors. This area requires further research, and health authorities continue to monitor the evidence. Individuals at high risk for heart disease may wish to discuss their intake with a healthcare provider.
Comparison of Sweeteners
| Feature | Added Sugar Alcohols (Polyols) | Standard Table Sugar (Sucrose) | Artificial Sweeteners |
|---|---|---|---|
| Calories (kcal/g) | 0–3 | 4 | 0 |
| Sweetness (vs. Sugar) | 40-100% | 100% | 200–13,000x sweeter |
| Glycemic Impact | Low to moderate | High | Negligible (zero) |
| Dental Effects | Non-cariogenic; some (xylitol) prevent cavities | Cariogenic (causes tooth decay) | Non-cariogenic |
| GI Side Effects | Potential bloating, gas, laxative effect | None (in moderation) | Usually none |
| Labeling | Listed as 'Sugar Alcohol' under carbohydrates | Included in 'Total Sugars' and 'Added Sugars' | Listed as individual ingredients |
How to Spot Added Sugar Alcohols on Labels
To identify added sugar alcohols, you need to read both the ingredient list and the Nutrition Facts panel.
- Nutrition Facts Panel: Check the 'Total Carbohydrate' section for a line item that says 'Sugar Alcohol'. This indicates the total amount of polyols per serving.
- Ingredient List: Look for ingredients ending in “-itol,” such as erythritol, xylitol, sorbitol, and maltitol. Other names to watch for include isomalt and hydrogenated starch hydrolysates (HSH). Remember that ingredients are listed in descending order by weight, so the higher up the list a polyol is, the more of it is present in the product.
Conclusion
Added sugar alcohols serve as a valuable tool for reducing calorie intake and managing blood sugar, and they offer a significant advantage for dental health over traditional sugar. However, they are not a perfect substitute and require careful consumption to avoid potential digestive side effects. Reading food labels to understand what you're consuming is essential. While recent concerns surrounding specific polyols like erythritol highlight the need for continued research, moderate consumption as part of a balanced diet can be a reasonable strategy for those looking to curb sugar consumption. For more information, consult the U.S. Food & Drug Administration guidelines on reading nutrition labels.
