Sugar alcohol

Sugar alcohol (also polyol): Sugar alcohols (also called polyols) are sugar substitutes used widely in "sugar-free" candy, gum, protein bars, and keto baking. They taste sweet but are absorbed differently than table sugar — most have lower glycemic impact, and some have effectively none.

Common types

Erythritol (GI = 0, no glucose impact), allulose (GI = 0), xylitol (GI ≈ 7), sorbitol (GI ≈ 9), maltitol (GI ≈ 35 — much higher than the others), isomalt (GI ≈ 9). The "subtract half from net carbs" rule is a reasonable default if you don't know which one.

Side effects

Most sugar alcohols can cause GI distress (gas, bloating, diarrhea) at high doses because they reach the large intestine partially undigested. Tolerance varies dramatically between individuals.

On the label

When a product contains sugar alcohols, U.S. labels list them on a separate "Sugar Alcohols" line below Total Carbohydrate. They're included in the Total Carbohydrate number.