Answer: Due to malabsorption of Vitamin B12
Explanation:
The patients of gasrectomy face several problems which includes anemia as a result of iron or Vitamin B12 malabsorption.
This problem takes place when the intrinsic factor is not produced by the stomach, which helps in the absorption of iron. This is because the proximal part of the stomach is cut.
In this case the iron is not properly absorbed due to this patients with partial gastrectomy face several problems.