Sugar Alcohols and Your Gut: Why Erythritol, Xylitol, Sorbitol, and Maltitol Cause Symptoms
Meta:
- Category: Ingredients
- Author: ImproveGutHealth Team
- Date: July 7, 2026
- Read Time: 7 min
- Tags: [Sugar Alcohols, Polyols, Erythritol, Xylitol, Sorbitol, Maltitol, FODMAP, Bloating]
Disclaimer
This content is for informational purposes only and is not medical advice. It is not a substitute for professional diagnosis or treatment. If you have severe or persistent GI symptoms, consult a qualified clinician.
The quick answer
Sugar alcohols (polyols) are FODMAPs. They pull water into the gut and feed gas-producing bacteria, which is why they cause bloating, gas, cramping, and diarrhea in many people — especially at higher doses.
The five you encounter most often, ranked from least to most gut-active:
- Erythritol — small molecule, mostly absorbed in small intestine, generally well-tolerated at moderate doses
- Xylitol — moderate gut activity, also toxic to dogs (worth mentioning because it's in so many products)
- Sorbitol — more gut-active, slow absorber
- Maltitol — high FODMAP, major offender in keto / sugar-free products
- Mannitol — high FODMAP, often the worst offender
If your "sugar-free" or "keto" product is causing bloating and diarrhea, the polyols are almost always why.
What sugar alcohols actually are
Sugar alcohols (polyols) are carbohydrates that chemically look like a hybrid of sugar and alcohol. They occur naturally in small amounts in some fruits and vegetables (pears, apples, mushrooms, cauliflower) but are mostly manufactured for use as low-calorie sweeteners.
They're sweet (most are 60–90% as sweet as sugar), have fewer calories than sugar, and don't raise blood sugar as much — which is why they're popular in:
- Sugar-free candy and gum
- Keto products
- Protein bars and powders
- "Diet" or "sugar-free" beverages
- Toothpaste and mouthwash
- Some "natural" sweetener blends
The problem: most of them are FODMAPs — specifically the polyol category in the FODMAP acronym (F-ermentable O-ligosaccharides D-isaccharides A-nd M-onosaccharides P-olyols).
Why they cause gut symptoms
Two mechanisms, both operating:
1. Osmotic effect
Sugar alcohols are slowly absorbed in the small intestine. The unabsorbed portion draws water into the gut lumen by osmosis. More water in the gut = looser stools and faster transit.
For most people, this is mild. For people with pre-existing motility issues or visceral hypersensitivity, it can be dramatic — urgent, watery diarrhea within 30–90 minutes of consumption.
2. Bacterial fermentation
The unabsorbed portion reaches the colon, where resident bacteria ferment it. This produces hydrogen, methane, and short-chain fatty acids — which is gas, bloating, and distension.
For people with SIBO or dysbiosis, this is worse because the bacterial populations are already overgrown or imbalanced.
The five common polyols, ranked
1. Erythritol — usually fine in small doses
The smallest molecule. About 60–90% is absorbed in the small intestine via passive diffusion. The remainder is excreted unchanged in urine — minimal fermentation.
Tolerated by: most people, even those with IBS, at doses up to ~30–50g per sitting.
Triggers symptoms in: some people with severe dysbiosis or extremely low FODMAP tolerance. A 2023 Cleveland Clinic study also raised cardiovascular questions for high-dose erythritol, though causality is debated.
Found in: Swerve, monk fruit + erythritol blends, many keto products, some protein bars.
2. Xylitol — moderate, with a dog caveat
About 50% absorbed in the small intestine. The rest ferments in the colon, producing gas. Moderate FODMAP rating.
Tolerated by: most people at doses under 15–20g per sitting.
Triggers symptoms in: people with existing dysbiosis, SIBO, or low polyol tolerance.
Important: Xylitol is highly toxic to dogs — even small amounts can cause rapid hypoglycemia and liver failure. If you have a dog, xylitol-containing products (especially sugar-free gum, peanut butter, baked goods) need to be locked away.
Found in: sugar-free gum, mints, some "natural" toothpastes, baking substitutes.
3. Sorbitol — moderate to high
Slow absorber, more osmotic effect. Moderate-to-high FODMAP rating.
Tolerated by: most people at doses under 10–15g per sitting. Sensitive people react at lower doses.
Triggers symptoms in: people with IBS, fructose malabsorption (often overlaps), and dysbiosis.
Found in: diet products, sugar-free candy, dried fruit (often used as a preservative in prunes, pears, apples), some medications.
4. Maltitol — high, the biggest offender
Slowest absorber, most osmotic effect, significant fermentation. High FODMAP rating. The most common offender in keto products and sugar-free candy.
Tolerated by: very few people with existing gut issues, often causes symptoms in healthy people too at doses above 15–20g.
Triggers symptoms in: most people with IBS, dysbiosis, SIBO, or healthy guts at higher doses.
Found in: sugar-free chocolate, low-carb ice cream, keto candy, protein bars, some "no-sugar-added" products.
5. Mannitol — high, often hidden
High FODMAP rating. Found naturally in some foods (mushrooms, cauliflower, celery) and used as an additive in some processed products.
Tolerated by: few people with gut sensitivity, even healthy people can react at moderate doses.
Triggers symptoms in: most people with IBS or dysbiosis.
Found in: some sugar-free products, naturally in button mushrooms, cauliflower, watermelon, sweet potatoes.
Practical guidance
Read labels — the dose matters more than the polyol
Sugar alcohols are listed individually on US nutrition labels (since 2020 FDA mandate). European labels often lump them as "polyols." Check both the type and the total grams per serving.
A "sugar-free" product with 5g of erythritol per serving is usually fine. A "sugar-free" product with 20g of maltitol per serving is going to wreck most people.
The hidden sources
Sugar alcohols aren't always obvious. Watch for:
- "Sugar-free" or "no sugar added" labels
- "Keto-friendly" labels
- "Low-carb" protein bars
- "Natural sweetener" marketing (often hides polyols)
- Toothpaste and mouthwash (you swallow some)
- Medications (liquid versions often use sorbitol or mannitol as carriers)
- Dried fruit (often preserved with sorbitol)
What to use instead
For people with gut sensitivity:
- Stevia — non-FODMAP, generally well-tolerated. Some find the aftertaste objectionable.
- Monk fruit — non-FODMAP, well-tolerated. Often blended with erythritol (check).
- Allulose — small amounts are non-FODMAP; well-tolerated. Some people react at higher doses.
- Regular sugar — in moderation. Sugar is not FODMAP and doesn't cause the same gut symptoms at reasonable doses. The "sugar is bad" narrative for everyone has been overstated.
- Small amounts of honey or maple syrup — both low-to-moderate FODMAP in small quantities (honey is high in fructose, so larger servings can trigger symptoms in fructose-malabsorbers).
Tolerance testing
If you want to know your personal polyol tolerance:
- Remove all polyols for 2 weeks
- Reintroduce one at a time, starting with erythritol (lowest impact)
- Test 5–10g of erythritol first; if no symptoms, try 20g
- If erythritol is fine, try xylitol next
- Then sorbitol, then maltitol, then mannitol
- Record symptoms for 24 hours after each test (delayed reactions possible)
This gives you a personalized tolerance map.
The keto connection
Many keto products are loaded with maltitol specifically — it tastes the most like sugar and provides bulk. This is why some people who go keto feel worse, not better: the maltitol in the "keto" candy and ice cream is fermenting in their colon and causing massive gas, bloating, and diarrhea.
If you're doing keto for gut health and feeling worse, check the labels. Switch to products sweetened with stevia, monk fruit, or allulose instead.
The diabetes connection
Sugar alcohols don't raise blood sugar as much as sugar, which is why they're popular in "diabetic-friendly" products. But the gut symptoms are real and often severe. People with diabetes plus IBS or dysbiosis are particularly vulnerable.
If you have diabetes plus gut symptoms, work with your clinician on a plan that addresses both. Don't accept "just deal with the GI side effects."
The bottom line
If your "sugar-free" or "keto" products are causing bloating, gas, or diarrhea, the polyols are almost certainly why. Erythritol is the safest starting point; maltitol is the most common offender. Stevia, monk fruit, and allulose are the best alternatives for sensitive guts.
See also: