Regarding intestinal adaptation

Quotes from "Pediatric Surgery (Springer Surgery Atlas)" by Prem Puri, Michael E. Höllwarth -

"Resection of the jejunum is well tolerated owing to the enormous adaptive capacity of the ileum, the intact enterohepatic circulation of bile salts, and the preserved absorption of fat-soluble vitamins and vitamin B12. In contrast, if the entire ileum is lacking, absorption of nutrients is significantly more difficult because of the limited intestinal adaptation capacities of the jejunum. Nonabsorbed intestinal contents, including bile acids, spill over into the colon and may cause significant diarrhea. Furthermore, loss of the ileum leads to a reduction of the bile salt pool, malabsorption of fat and fat-soluble vitamins, and a vitamin B12 deficiency."

"The pathophysiological process that follows an extensive loss of small bowel is called intestinal adaptation. It includes (1) morphological changes leading to an increase of absorptive surface area, (2) functional changes resulting in augmentation of the absorptive capacity of the remaining enterocytes, and (3) increased intestinal diameter with a concomitant reduction of motility, thereby slowing down the intestinal transit time of chyme."

"The presence of intraluminal food is the most important driving force for intestinal adaptation. Enteral nutrients stimulate gastrointestinal secretions and hormones that are known to exert trophic effects on the mucosa. Recent evidence suggests that glucagon-like peptide 2, human growth hormone, epidermal growth factor, and insulin-like growth factor I may play an important role in the process of intestinal adaptation."