ileal resection leads to vitamin b12 deficiency

Ileal section leads to vitamin B12 deficiency, bile salt malabsorption (subsequent malabsorption of fats and fat-soluble vitamins), and secretory diarrhea.  The secretory diarrhea is due to malabsorbed bile acids entering the colon causing colonic stimulation; cholestyramine lessens this process by binding the bile acids.  Treatment for patients with ileal resection also involves supplementation of vitamin B12 and other fat-soluble vitamins.