Xylitol vs Allulose: 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 Allulose?

Allulose (D-psicose) is a rare sugar monosaccharide naturally present in trace amounts in wheat, figs, raisins, and jackfruit. It has about 70% of sucrose's sweetness but provides only 0.4 kcal/g (about 10% of sucrose's calories) because it is absorbed but not metabolized. The FDA exempted allulose from the 'total sugars' declaration in 2019.

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.

Allulose: Generally considered safe with a favorable glycemic profile. Human studies show that allulose does not raise blood glucose or insulin. GI effects (bloating, abdominal cramping, diarrhea) have been reported in dose-response studies above 0.4 g/kg body weight; a 2016 study in the journal Food & Chemical Toxicology established a no-observed-adverse-effect level (NOAEL) in humans. Compared to erythritol, no cardiovascular concerns have been raised in the literature.