Ascorbic Acid vs Xylitol: which is worse?

What is Ascorbic Acid?

Ascorbic acid is the chemical name for vitamin C, an essential water-soluble vitamin found abundantly in fruits and vegetables. As a food additive (E300), it functions as an antioxidant preservative, preventing oxidative browning and rancidity. Commercial ascorbic acid is produced by fermentation of glucose, most commonly from corn.

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.

Documented risks

Ascorbic Acid: Generally recognized as safe. Note: when ascorbic acid is combined with sodium benzoate or benzoic acid in acidic beverages, benzene can form — a Class 1 carcinogen. This combination should be avoided in formulations. As a standalone additive, ascorbic acid is not only safe but nutritionally beneficial. Very high supplemental doses (>2 g/day) can cause diarrhea and kidney stone risk in predisposed individuals.

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.