Which sugar alcohol, when consumed in excess, can cause osmotic diarrhea, bloating, and abdominal discomfort?

• A. Mannitol
• B. Glycerol
• C. Sorbitol
• D. Xylitol

Answer: (C)

Osmotic diarrhea from sugar alcohols happens because these compounds are not fully absorbed in the small intestine. When you ingest more than the small intestine can absorb, the unabsorbed portion stays in the lumen and pulls water into the bowel by osmosis, leading to looser stools. The remaining sugar alcohol that reaches the colon is also fermented by gut bacteria, producing gas and causing bloating and abdominal discomfort.

Sorbitol is particularly notorious for this effect because it is poorly absorbed, so even moderate excess intake can create a strong osmotic load and GI symptoms. It’s a common sweetener in sugar-free gums, candies, and some laxatives, which is why it’s the classic culprit for osmotic diarrhea with ingestion of excess amounts.