The ileum can absorb most of the nutrients absorbed in the proximal small bowel, its adaptive ability is greater than the jejeunum. The ileum is the only site where bile salts are absorbed and enter their enterohepatic circulation. In addition to bile salts, vitamin B12 complexed with gastric intrinsic factor is absorbed only in the ileum. The normal liver usually has enogh B12 stored up for about 3 years so deficiency is only a problem in the longer term.