Ms. Wang brought her mother to the hematology clinic, saying that her mother had a bad complexion, no energy, and often felt numbness in her hands, feet, and tongue pain, fearing that it was a “mini-stroke”. She went to the neurology department and had a cranial CT done, but the doctor said there was no “mini-stroke” and suggested a hematologist to take a look. The old man did look pale and anemic. The old man was asked to open his mouth, and there were only a few teeth left. When the old man was asked to stick out his tongue, the tongue papillae were atrophied, the surface was smooth, and the tongue was blood red, like a piece of beef. Ask the old man about his usual diet, he complained that his teeth were not good and he did not want to eat anything because his tongue was always sore. Ms. Wang also anxious to add: old mother Ningbo people, usually eat some porridge, eat some favorite curd. Based on these conditions, the doctor asked the old man to go for blood tests to check routine blood, serum vitamin B12 and serum folic acid. As a result, the old man was clearly diagnosed with megaloblastic anemia with vitamin B12 and folic acid deficiency. After 2 weeks of treatment with vitamin B12 intramuscular injection and folic acid tablets orally, the old man’s symptoms of numbness in hands, feet and tongue pain were significantly relieved, and his anemia was greatly improved, and he had a taste for food. After 2 more weeks of treatment, the blood routine was completely back to normal. The doctor advised the old man to get dentures, at least not to interfere with eating, and to have a balanced diet, paying attention to the intake of meat and fresh fruits and vegetables. Megaloblastic anemia is a type of nutritional anemia that is not uncommon in clinical practice and is overwhelmingly caused by vitamin B12 and/or folic acid deficiency. Vitamin B12 is mainly taken from animal foods such as meat, liver, fish, eggs and dairy products, while folic acid is mainly taken from fresh green leafy vegetables, liver, kidney, yeast and mushrooms. A chronically low diet, or a long-term vegetarian diet, or improper food processing that destroys large amounts of folic acid can cause megaloblastic anemia. Vitamin B12 is mainly absorbed in the stomach in the jejunum after combining with internal factors, and folic acid is mainly absorbed in the duodenum and proximal jejunum; therefore, total or major gastric resection, destruction of gastric mucosa, and small intestine diseases can affect the absorption of vitamin B12 and folic acid. In addition, long-term hemodialysis can lead to excessive loss of vitamin B12 and folic acid, and certain drug factors can lead to impaired vitamin B12 and folic acid utilization. In the long run, megaloblastic anemia is inevitable. Both vitamin B12 and folic acid deficiency can cause anemia, leukemia and thrombocytopenia, loss of appetite, bloating and diarrhea, tongue inflammation and tongue pain, red tongue, and atrophy of the tongue papillae. Vitamin B12 deficiency can also cause neurological manifestations and mental symptoms, such as tiredness and weakness, numbness of hands and feet, sensory disorders, difficulty walking, ataxia, unsteady gait, lack of desire to sleep, mental confusion, taste, smell, vision loss and even incontinence, etc. Folic acid deficiency can also cause irritability, delusions, emotional disorders, etc. Since the physiological demand for vitamin B12 and folic acid is very small, the above symptoms often occur slowly and unknowingly and are easily overlooked. Especially the elderly, in order to lower blood pressure, blood sugar and blood lipids, they think “it’s better to eat less”, “I’m retired at home anyway, so I can eat whatever I want”, and they don’t take it seriously even if their teeth fall out and affect their diet. When dizziness, hand numbness, foot numbness, etc. occur, the first reaction is “will it be a stroke”, and some elderly people will increase the dose or variety of blood-stasis-activating drugs without authorization. In fact, megaloblastic anemia is not difficult to diagnose and treat as long as it is thought of, and the treatment is very effective, and it can generally return to normal within 1 to 2 months after effective treatment. However, if it is delayed for too long and the neurological symptoms persist for more than 1 year, it will be difficult to recover. By the way, it is reminded that the physiological demand of infants, adolescents and pregnant women is high, and the demand of certain diseases such as hyperthyroidism and chronic hemolysis is also increased, such as paying attention to the supplementation of fresh vegetables and animal protein, or appropriate supplementation of folic acid, when it can prevent the occurrence of megaloblastic anemia. Total gastrectomized patients should be given prophylactic intramuscular injections of vitamin B12 once a month.