The Truth About Subtracting Sugar Alcohols
Navigating the world of carbohydrate counting can be tricky, especially when it comes to sweeteners like sugar alcohols. Unlike regular sugar, which your body readily absorbs and uses for energy, sugar alcohols are only partially digested. This is why they have fewer calories and a lesser impact on blood sugar levels, leading to the practice of subtracting them from total carbs to find "net carbs." However, this practice is not a universally recognized scientific method and requires careful attention to detail.
What Are Sugar Alcohols?
Sugar alcohols, also known as polyols, are a class of low-calorie carbohydrate sweeteners found naturally in some fruits and vegetables. Industrially produced versions are used in many "sugar-free" and "keto-friendly" products, including candies, gums, and baked goods. They provide sweetness without the same glycemic impact as regular sugar, but they still contain some calories and carbohydrates.
Common Sugar Alcohols
- Erythritol: Often considered the best option for low-carb diets as it is poorly absorbed and has virtually no caloric or blood sugar impact.
- Xylitol: Found in many sugar-free gums and mints, it has a lower glycemic index than sugar but still affects blood sugar to a degree. Note that it is highly toxic to dogs.
- Maltitol: Commonly used in sugar-free chocolates and candies, it has a higher glycemic index than erythritol and can significantly impact blood sugar for some individuals.
- Sorbitol: Naturally found in fruits, it is about half as sweet as sugar and can cause significant digestive issues if consumed in excess.
- Isomalt: Often used in hard candies and cough drops due to its stability during heating.
How to Calculate Net Carbs: The Right Way
The formula for calculating net carbs is typically Total Carbs - Fiber - (some) Sugar Alcohols. The key is understanding that you do not subtract all sugar alcohols equally. While a standard approach is to subtract half the grams of most sugar alcohols, specific rules apply to different types.
For example, if a product contains 20g of total carbs, 5g of fiber, and 10g of maltitol, the calculation would be: 20g - 5g - (10g / 2) = 10g net carbs. If that same product contained erythritol instead of maltitol, the full amount would be subtracted, resulting in fewer net carbs. For people counting carbohydrates for managing conditions like diabetes, it's crucial to understand these variations and monitor blood glucose levels.
The Official Stance vs. Popular Practice
Organizations like the American Diabetes Association (ADA) and the Food and Drug Administration (FDA) do not officially endorse the concept of "net carbs". They emphasize tracking total carbohydrates and being mindful of how different foods affect your personal blood sugar response. While the ADA acknowledges that some sugar alcohols have a lesser effect on blood sugar, they recommend subtracting only half of the sugar alcohol grams from the total carbohydrate count. This conservative approach is based on the partial absorbability of most polyols.
For those on the keto diet, counting net carbs is a popular method to stay within daily limits and maintain ketosis. However, even within the keto community, there is debate, with some individuals choosing to count total carbs to avoid any potential impact from sugar alcohols. Ultimately, the most reliable method for any diet is to observe your own body's reaction and adjust accordingly.
Why the Digestive Impact Matters
Beyond their glycemic effect, sugar alcohols are known to cause gastrointestinal distress in some individuals, particularly when consumed in large quantities. This is because they are not fully absorbed in the small intestine and instead ferment in the large intestine, leading to symptoms like gas, bloating, and diarrhea. The intensity of this effect varies by sugar alcohol, with erythritol being generally better tolerated than others like sorbitol or mannitol. This digestive aspect is another reason why a one-size-fits-all subtraction rule is insufficient.
Total Carbs vs. Net Carbs: What to Count
| Feature | Total Carbs | Net Carbs (Popular Method) |
|---|---|---|
| Calculation Basis | Sum of all carbohydrates: starches, sugars, fiber, and sugar alcohols. | Total carbs minus dietary fiber and a portion of sugar alcohols. |
| Digestibility | Includes both digestible and non-digestible carbs. | Focuses only on digestible carbohydrates that impact blood sugar. |
| Official Recognition | Recognized and regulated by the FDA and ADA. | Not officially defined or regulated by major health bodies. |
| Use Case | Recommended for most people, especially those managing diabetes, for a more conservative and accurate count. | Commonly used by individuals on low-carb or keto diets to track "effective" carbs. |
| Effect on Blood Sugar | Captures the full potential blood sugar impact. | Aims to capture a more realistic blood sugar impact, but can be inaccurate depending on the sugar alcohol. |
Conclusion
In summary, the question of whether to subtract sugar alcohols from total carbs does not have a simple yes-or-no answer. For low-carb and keto dieters, subtracting half of most sugar alcohols (or the full amount of erythritol) is a common practice to arrive at a net carb count. However, this method is not officially recognized and can be inaccurate, as different sugar alcohols have varying effects on blood sugar. For better health management, particularly for those with diabetes, relying on the total carbohydrate count is often the more cautious and recommended approach by official health bodies like the American Diabetes Association. The best strategy is to be aware of the specific sugar alcohol used, moderate consumption, and monitor your body's individual response.
For more detailed information on understanding carbohydrate counts and managing your diet, consult a trusted resource like the American Diabetes Association.
