Sweet Sugar Alcohols
You’ve probably noticed sugar alcohols before in chewing gum, candies, baked goods, ice cream and diet drinks. These products are also often labeled “sugar free”, “low in calories”, “diabetic-friendly”, and even “tooth-friendly”. Suspicious? We don’t blame you—when you see the words sugar and alcohol together, there’s plenty of reason to start asking questions. However, upon learning a little about these ingredients you’ll find they have unique benefits.
Sugar alcohol sounds worse than it is because chemists create names based on structures—it’s not the type of alcohol that makes you drunk! Sugar alcohols are so named because they are little carbon rings with OH (oxygen-hydrogen) groups on them, also called polyols. These polyols are naturally found in many plants and are easily recognized by the human body (in fact, human cells produce their own sugar alcohols such as sorbitol).
Fewer calories, greater flavor
The truth is that sugar alcohols, when used in correct amounts, can be safe, natural and healthy. They do provide sweetness and energy, but they have fewer calories than sugar (1-3 per gram versus 4 per gram). This results in a low impact on blood sugar and insulin levels, which is why sugar alcohols are often used in products intended for diabetics.
Some sugar alcohols can also be fermented by friendly probiotic bacteria that make up a healthy intestinal flora. A healthy intestinal flora helps support your immune system and can help improve digestion. In addition, sugar alcohols are seldom able to be metabolized by oral bacteria, which is why they’re “tooth-friendly”. They avoid promotion of tooth decay and cavities.
When used in foods, sugar alcohols can be especially useful. They provide bulk and texture that makes foods and candies more enjoyable to consumers. They enhance and deliver a lasting flavor of sweetness as well as provide a “cooling effect”. Particularly in baked goods, they help prevent browning when exposed to heat and also help those foods stay moist over time.
Not all sugar alcohols are the same. There are many with varying attributes. Maltitol, for example, acts in a different way than, say, xylitol. Maltitol is a disaccharide like sucrose (table sugar) and has almost the same level of sweetness and other properties. This makes it very useful for replacing table sugar while offering fewer calories and avoiding promotion of tooth decay.
When consumed, maltitol is broken down by enzymes to glucose and sorbitol. The glucose is easily absorbed, but the sorbitol is resistant to digestion. Because of its resistance to digestion, sorbitol works in similar fashion to prebiotic fiber, fermenting and feeding that helpful intestinal bacteria.
With maltitol, however, there is a concern about overconsumption, especially in people who are unused to sugar alcohols. Consuming an excess of 10g may cause bloating. And, in absence of soluble fiber, consumption of 20g or more can cause loose stool or diarrhea. You’d have the same laxative effect from eating too many fruits like plums, prunes, apples, pears and cherries. These fruits are all high in sorbitol.
Xylitol and Erythritol
What about xylitol and erythritol? These sugar alcohols are not quite as sweet as sugar or maltitol. And they have a stronger cooling effect than any of the other sugar alcohols. You’d recognize their flavor from sugar-free chewing gum. Like maltitol and sorbitol, they offer fewer calories than sugar and don’t promote tooth decay.
Unlike their counterparts, however, xylitol and erythritol are unlikely to ferment and cause bloating or diarrhea. They are considered non-fermentable because intestinal bacteria have difficulty digesting them. After consumption, most erythritol is absorbed easily into the bloodstream, while xylitol is absorbed more slowly.
Xylitol is notable because it’s found to be more effective than other sugar alcohols in reducing cavities. According to recent studies, primarily from Finland, xylitol may not only reduce potential cavities from forming, but even strengthen teeth. Its mechanism is thought to occur by attracting and “starving” cavity-producing bacteria. The Finnish were the first to extract xylitol from birch, but it’s found in many plants, fruits and vegetables, especially berries, plums and raspberries.
Erythritol is naturally found in grapes, melons and mushrooms, as well as in fermented foods like wine, beer and cheese. Because of its ultra-low impact on blood sugar, you’ll also find erythritol often paired with sugars to lessen its blood-sugar effects in foods, with other sugar alcohols, or with natural sweetening herbs such as stevia in natural sweetener packets.
Reference: Brown A. Understanding Food: Principles and Preparation, 3rd ed. Wadsworth, Cengage Learning. 2008.