<prompt> All are true regarding osmotic diarrhea EXCEPT:Due to highly osmotic substances in lumenFasting may improve symptomsStool reducing substances are presentCan be mediated by bacterial toxins  <response>: Osmotic diarrhea is caused by nonabsorbed nutrients in the intestinal lumen as a result of one or more of the following mechanisms: 1 intestinal damage e.g., enteric infection; 2 reduced absorptive surface area e.g., active celiac disease; 3 defective digestive enzyme or nutrient carrier e.g., lactase deficiency; 4 decreased intestinal transit time e.g., functional diarrhea; and 5 nutrient overload, exceeding the digestive capacity e.g., overfeeding, sorbitol in fruit juice. Whatever the mechanism, the osmotic force generated by nonabsorbed solutes drives water into the intestinal lumen. A very common example of osmotic diarrhea is lactose intolerance. Lactose, if not absorbed in the small intestine, reaches the colon, where it is fermented to sho-chain organic acids, releasing hydrogen that is detected in the lactose breath test, and generating an osmotic overload. Another risk for chronic osmotic diarrhea often noted in patients with diarrhea-associated irritable bowel syndrome are foods containing FODMAPs fermentable oligo- di-monosaccharides and polyols. 