Xylitol vs Erythritol: 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 Erythritol?

Erythritol is a four-carbon sugar alcohol naturally occurring in small amounts in fruits, fermented foods, and mushrooms. Commercially produced via fermentation of glucose by yeasts such as Moniliella pollinis, it has approximately 70% of sucrose's sweetness, provides 0.24 kcal/g, and has a glycemic index of 0. It is nearly completely absorbed in the small intestine and excreted unchanged in urine, which explains its unusually low laxative effect compared to other polyols.

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.

Erythritol: A 2023 observational study published in Nature Medicine (Hazen et al., Cleveland Clinic) found that elevated blood erythritol levels were associated with increased risk of major adverse cardiovascular events (MACE), including heart attack and stroke. Additionally, erythritol was found to enhance platelet aggregation in vitro. This study was widely reported and has generated significant scientific debate; critics note that it was observational (not causational), and that the study population had pre-existing cardiovascular risk factors. Regulatory agencies have not changed their approval status. The long-term cardiovascular implications require further research.