Sugar alcohols are common ingredients in many “sugar-free” or “reduced-sugar” products, offering sweetness with fewer calories and a different impact on the body compared to traditional sugars. This distinction is particularly relevant for individuals managing carbohydrate intake or blood sugar levels.
Understanding Sugar Alcohols
Sugar alcohols, also known as polyols, are a type of carbohydrate that chemically combines characteristics of both sugars and alcohols. They have a unique chemical structure, influencing how the body processes them. Despite their name, they do not contain ethanol, the type of alcohol found in beverages. They are organic compounds derived from sugars, featuring multiple hydroxyl (-OH) groups attached to each carbon atom.
These compounds occur naturally in small quantities in various fruits and vegetables like apples, pears, berries, and some mushrooms. However, the sugar alcohols frequently found in processed foods are typically produced industrially from other carbohydrates, such as glucose or starch. Common examples include erythritol, xylitol, sorbitol, maltitol, mannitol, isomalt, and lactitol.
How Sugar Alcohols Are Digested
A key difference between sugar alcohols and regular sugars lies in their digestion and absorption. Sugar alcohols are not fully absorbed by the small intestine in the same way as traditional carbohydrates. This incomplete absorption is a primary reason they contribute fewer calories per gram than sugar, typically ranging from 0.2 to 3 calories per gram compared to sugar’s 4 calories per gram.
A significant portion travels largely undigested to the large intestine. Here, gut bacteria ferment these compounds. This fermentation process can lead to the production of gases and short-chain fatty acids, influencing the caloric contribution and potential digestive effects. Erythritol stands out among sugar alcohols as it is absorbed more completely in the small intestine and then excreted unchanged in urine, resulting in almost no caloric contribution and minimal digestive impact.
Impact on Blood Glucose and Insulin
The incomplete digestion of most sugar alcohols directly translates to a reduced impact on blood glucose levels and insulin response. This characteristic makes them a popular choice in foods marketed towards individuals managing diabetes or those on low-carbohydrate diets.
The glycemic impact varies significantly among different types of sugar alcohols. For instance, erythritol has a negligible effect on blood glucose and insulin levels due to its unique absorption and excretion pathway. In contrast, maltitol, while still having a lower glycemic index than sugar, can have a more noticeable effect on blood sugar, particularly in larger quantities, because a greater portion of it is absorbed. Individual responses can also vary based on factors such as the specific sugar alcohol consumed, the amount, and individual metabolic differences.
Calculating Net Carbohydrates
For individuals tracking carbohydrate intake, particularly those following low-carb diets, understanding how sugar alcohols fit into “net carbohydrate” calculations is important. Net carbohydrates represent the portion of total carbohydrates that the body can fully digest and convert into glucose, thereby affecting blood sugar. The common practice for calculating net carbs often involves subtracting fiber and a portion of sugar alcohols from the total carbohydrate count.
However, this is not a blanket subtraction of 100% of sugar alcohols. Many health organizations suggest subtracting half of the sugar alcohol grams from total carbohydrates if the food contains more than 5 grams of sugar alcohols.
Considerations for Consumption
While sugar alcohols offer benefits like reduced calories and a lower glycemic impact, there are considerations for their consumption. This may include symptoms such as bloating, gas, and diarrhea, especially when consumed in larger quantities.
The degree of digestive upset often depends on the specific sugar alcohol and individual sensitivity. For example, sorbitol and mannitol are known to cause laxative effects at relatively lower doses compared to erythritol, which is generally well-tolerated. Moderation is advisable, and individuals should assess their personal tolerance levels. Beyond digestive effects, some sugar alcohols, particularly xylitol, are recognized for their dental health benefits, as they do not promote tooth decay and can even inhibit oral bacteria.