Key takeaways
- Sugar alcohols (polyols) are carbohydrates used as sweeteners; they appear under 'Total Carbohydrate' on a Nutrition Facts label.
- They differ substantially from one another in how completely they are absorbed, which is why they are not interchangeable.
- Incomplete absorption is the reason for the digestive effects reported with some of them, and tolerance varies between individuals.
- Low-carb net carb conventions subtract some or all sugar alcohol grams, but the convention is not standardised and different apps and brands do it differently.
- 'Sugar free' on a package does not mean carbohydrate free, and the label is the place to check.
Sugar alcohols are carbohydrates used as sweeteners, and despite the name they are not alcohol in the drinking sense. The technical term is polyols, and the practical signal on an ingredient list is a name ending in -itol: erythritol, xylitol, maltitol, sorbitol, isomalt.
Where they appear on a label
Sugar alcohols are counted inside Total Carbohydrate on a Nutrition Facts label. Some labels also break them out on a separate "Sugar Alcohol" line.
That is the source of a persistent confusion. A package can say "sugar free" — which relates to sugars specifically — while containing a substantial amount of carbohydrate in the form of polyols. The two claims are not in conflict; they are about different things.
The FDA's guide to reading the Nutrition Facts label is the reference for how these lines relate, and how to read nutrition labels covers the full label in practical terms.
Why they are not interchangeable
The most useful thing to know about polyols is that they differ substantially from one another, and treating them as one category is where people get caught out.
The main dimension of difference is how completely each is absorbed in the small intestine. That single property drives most of the practical differences:
| Property | Consequence |
|---|---|
| More completely absorbed | Fewer digestive effects, more carbohydrate reaching the body |
| Less completely absorbed | More reaches the large intestine, more potential for digestive effects |
Published reviews of gastrointestinal effects discuss the polyols individually rather than as a group — the Int J Dent review of gastrointestinal disturbances associated with sugar alcohols is an example. The fact that the literature separates them is itself the useful signal.
Why they can cause digestive upset
The mechanism is straightforward. Whatever is not absorbed in the small intestine continues into the large intestine, where it draws water in and is fermented by gut bacteria. That combination produces the effects some people report.
Two practical implications:
Dose matters. Effects reported at higher intakes may not occur at lower ones.
Individuals differ. Tolerance varies between people, and a polyol that causes one person no trouble at all can affect another. Your own experience is more informative than a general statement.
Anyone with an existing gastrointestinal condition should treat this as a topic for their clinician rather than for experimentation.
The net carb question
This is where low-carb eaters most want an answer, and the honest answer is that there is not a single authoritative one.
Net carbs is a convention, not a regulatory definition. Different sources subtract different things:
- Some subtract fibre only.
- Some subtract fibre plus all sugar alcohols.
- Some subtract fibre plus a proportion of sugar alcohols, varying by which polyol.
That is why two apps, or an app and a product label, can report different net carb figures for the same food. Neither is lying; they are applying different conventions.
Net carbs explained covers the arithmetic and its limits in detail, and keto macros explained covers where net carbs sit in a wider low-carb plan.
What we would suggest practically: pick one convention and apply it consistently, so your own numbers are comparable to each other over time. Comparing today's figure computed one way against last month's computed another way tells you nothing.
What a label will and will not tell you
It will tell you: total carbohydrate, and often the sugar alcohol total.
It will not tell you: which specific polyol, unless you read the ingredient list; how you personally will tolerate it; or what net carb figure any particular diet would assign.
The ingredient list is where the specific polyol name appears, which is why it matters more here than for most nutrients.
Where our app fits
Keto Diet Tracker: Low Carb subtracts fibre and sweeteners including erythritol, allulose and monk fruit from total carbohydrate automatically as you log, so the net carb figure is calculated rather than done by hand in a supermarket aisle.
That is an implementation of one convention, applied consistently. It is not a claim that this convention is the correct one — as above, there is no single authority. What consistency gives you is comparability across your own history.
The app is free to download on Google Play, supported by ads, with no in-app purchases. No account is required and your logs stay on your device rather than on our servers.
This article is general information, not medical or dietary advice, and it has not been reviewed by a doctor or registered dietitian. If you have a gastrointestinal condition, are managing diabetes, or take medication that interacts with what you eat, talk to a qualified healthcare professional. MedlinePlus is a reliable starting point for general information about carbohydrates. The rest of our nutrition tools are under health and nutrition.
Good to know
Frequently asked questions
What are sugar alcohols?
Where do they appear on a label?
Why do they cause digestive upset?
Do sugar alcohols count as carbs?
Are some better tolerated than others?
Sources
- Gastrointestinal Disturbances Associated with the Consumption of Sugar Alcohols with Special Consideration of Xylitol (Int J Dent 2016) (opens in a new tab)PubMed, U.S. National Library of Medicine — accessed
- How to Understand and Use the Nutrition Facts Label (opens in a new tab)U.S. Food and Drug Administration — accessed
- Carbohydrates (opens in a new tab)MedlinePlus, U.S. National Library of Medicine — accessed
