Gastrectomy patients can take oral vitamin B12 tablets, or injections of vitamin B12 or food fruits to supplement. After gastrectomy, due to the reduced secretion of endogenous factors, the patient’s absorption of vitamin B12 is reduced, resulting in vitamin B12 deficiency and can cause megaloblastic anemia, subacute combined degeneration of the spinal cord and other related pathologies. Therefore, to prevent vitamin B12 deficiency, vitamin B12 tablets can be taken orally. This drug is contraindicated in people who are allergic to vitamin B12, while it should be used with caution in patients with glaucoma. Possible adverse reactions include allergic symptoms such as rash, as well as hypokalemia and hyperuricemia. Injections of vitamin B12 liquid may also be considered for supplementation if oral intake is not effective. Other foods that contain vitamin B12 include: meat, such as pork, beef, lamb, chicken, etc.; animal offal, such as pig liver, pig heart, lamb liver, sheep heart, chicken liver, chicken heart, etc.; aquatic fish, such as grass carp, carp, scallop, yellow croaker, etc.; and fruits, such as apples, bananas, pears, and oranges. If vitamin B12 deficiency, it is recommended to consult a doctor in time and standardize the diagnosis and treatment under the guidance of a professional doctor, so as not to delay the condition.