Answer is A (Vitamin B12) Cyanocobalarnine (Vitamin B12) deficiency is the most common deficiency in patients with sho bowel syndrome associated with loss of ileum (ileal resection) since vitamin B12 is absorbed only in the ileum. `Cyanocobalamine (Vitamin B12) is the most common deficiency and occurs predictably after resection of 50-60 cm of the terminal ileum'. -- 'Complications in Surgery' (Lippincott Williams) 2"" (2011)/469 `Vitamin B12 and Bile acids are absorbed only in the ileum. Loss of ileum results in malabsorption of bile acids and vitamin B12 and consequent vitamin B12 deficiency'-- 'Sleisenger and Fordtran's Gastrointestinal Diseases' 81h/2258, 2264 Vitamin Deficiencies in Sho Bowel Syndrome Sho Bowel Syndrome with Extensive Jejunal Resection This is associated primarily with deficiency of fat soluble vitamins (A, D, E. K) The most common fat-soluble vitamins that are deficienci are vitamin A and D and to a lesser extent vitamin E followed by vitamin K. Vitamin A, D > Vitamin E >> Vitamin K Deficiency of vitamin K is uncommon as vitamin K is synthesized by colonic bacteria 60% of vitamin K is synthesized by colonic bacteria 40% of vitamin K is received by dietary intake Deficiency of vitamin K is therefore uncommon in patients with sho bowel syndrome who have an intact colon. Deficiency of vitamin K is however common in those patients with sho bowel syndrome who do not have a residual colon. Sho Bowel Syndrome with Extensive ileal resection This is associated primarily with deficiency of vitamin B12 since vitamin B12 is only absorbed in the terminal ileum. Fat soluble vitamin deficiencies may also occur due to fat malabsorption from decrease in concentration of bile acids / salts. (Bile acids are absorbed only from tr..; ileum) Vitamin B12 > Fat solubleVitamin The ileum has the capacity to adapt and compensate for jejunal resection. The jejunum does not have the capacity to adapt and compensate for ileal resection (as the terminal ileum has the exclusive capacity to reabsorb bile salts &vit BO