Xylitol vs Sorbitol: which is worse?

What is Xylitol?

Xylitol is a five-carbon sugar alcohol (pentitol) naturally found in birch wood, corn cobs, fruits, and vegetables. It has the same sweetness as sucrose but provides 40% fewer calories and does not raise blood glucose or insulin levels. Most commercial xylitol is produced from xylose derived from corn cob or hardwood hemicellulose hydrolysis.

What is Sorbitol?

Sorbitol is a sugar alcohol (polyol) naturally found in some fruits, including apples, pears, and prunes. Commercially, it is produced by hydrogenation of glucose. It has approximately 60% of the sweetness of sucrose but provides fewer calories (2.6 kcal/g vs 4 kcal/g for sugar) and does not cause a significant immediate insulin response.

Documented risks

Xylitol: Xylitol is safe for humans at normal consumption levels. Like other sugar alcohols, it can cause osmotic diarrhea and gastrointestinal upset at doses above 40–70 g/day. Critically, xylitol is highly toxic to dogs — even small amounts (0.1 g/kg body weight) can cause severe hypoglycemia and hepatic failure in canines, as documented in multiple veterinary case reports. The FDA and ASPCA have both issued warnings about xylitol pet toxicity. For humans, it is well-tolerated and has dental benefits.

Sorbitol: At doses above 20–50 g/day, sorbitol can cause osmotic diarrhea because it is incompletely absorbed in the small intestine and is fermented by colonic bacteria. EU regulations require products containing more than 10% added polyols to carry the label 'excessive consumption may produce laxative effects.' This is well-known and predictable. Sorbitol is not carcinogenic and does not raise blood glucose significantly, making it suitable for diabetics in controlled amounts.