Xylitol vs Polydextrose: 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 Polydextrose?

Polydextrose is a synthetic polymer of glucose (with some sorbitol and citric acid) created under heat and vacuum conditions. It functions as a soluble dietary fiber, providing only 1 kcal/g. It is used to add bulk to reduced-calorie foods while also contributing fiber content. The FDA approved it as GRAS in 1981.

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.

Polydextrose: At doses above ~90 g/day, polydextrose can cause flatulence, bloating, and loose stools. At normal food use levels it is well tolerated. EFSA confirmed its safety in 2012. It functions as a soluble prebiotic fiber, feeding beneficial gut bacteria. No genotoxicity, carcinogenicity, or reproductive toxicity has been identified.