Either megaloblastic anemia due to vitamin B12 deficiency (due to lack of intrinsic factor, which is necessary for B12 absorption and is normally produced by the parietal cells of the stomach) or microcytic anemia due to iron deficiency (due to decreased iron intake and impaired absorption in the duodenum) can result after paial gastrectomy. While folate deficiency can also cause megaloblastic anemia, it is rare after paial gastrectomy. Oral B12 is not a reliable method for correcting B12 deficiency; intravenous cyanocobalamin should be administered every 3 to 4 months for life. Other complications of paial gastrectomy includes osteoporosis secondary to impaired calcium absorption due to the Billroth II reconstruction (since calcium is normally absorbed in the proximal intestine--duodenum and jejunum). Also, fatty acids may also be malabsorbed due to inadequate mixing of bile salts and lipase with ingested fat, and therefore steatorrhea may result.