Oral vitamin B12 supplementation after total gastrectomy due to gastric cancer

Anemia is a frequent complication after gastrectomy due to deficiency of iron, vitamin B12 or folate, either alone or in combination. Vitamin B12 deficiency develops as a consequence of the decreased production of intrinsic factor which is essential for vitamin B12 absorption in the lower small bowel, and also because of a defect in the separation of vitamin B12 from its transporter protein. Vitamin B12 deficiency is a common cause of macrocytic anemia and has been implicated in a spectrum of neuropsychiatric disorders. To avoid that, parenteral iron treatment is recommended in these patients. However it is associated with high costs and patient discomfort, therefore, alternative ways of administration tend to be equated. Recently Kim Hyoung-Il showed that oral supplementation with vitamin B12 is an effective and safe treatment for vitamin B12 deficit in patients with gastric cancer who underwent total gastrectomy. Additionally, intramuscular vitamin B12 is no longer supplied in Portugal, being only available in hospital pharmacies. For this reason all gastrectomized patients are now treated with oral vitamin B12. This modification will certainly change the clinical practice in the management of gastrectomized patients since we consider that does not exist adequate clinical basis for the use of oral vitamin B12. In this context we consider this study appropriate in order to assess the clinical and laboratory efficacy of oral supplementation with vitamin B12 in gastrectomized patients due to gastric cancer, while others nutritional deficiencies are also assessed, such as iron deficiency and folate deficit, during a 2-year follow-up period. All patients will be treated with oral vitamin B12 (1000mg/day), 7 days post-operative. A patient diary will be used to monitor adherence to treatment.