A man was left battling diarrhea for more than three decades because of a rare genetic condition. The 33-year-old, who has not been named, had been plagued on-and-off loose stools since he was just ...

Osmotic diarrhea is when undigested material reduces how much water and electrolytes the bowels can absorb. It can occur when a person’s body has difficulty digesting certain foods, such as lactose.