Nutritional anemia, as the name implies, is a lower than normal amount of hemoglobin or red blood cell count due to nutritional deficiency. Nutritional anemia is divided into two major categories, one is iron deficiency anemia caused by iron deficiency, and the other is megaloblastic anemia caused by folic acid and vitamin B12 deficiency. Nowadays, we are all so well off that we don’t worry about food and clothing, and we worry about over-nutrition, so how can there be nutritional anemia caused by under-nutrition? Let’s take a look at it separately. What is iron deficiency anemia? Speaking of which, iron deficiency anemia is the most common nutritional anemia, and it is still a common and important health problem in countries all over the world, especially in developing countries. The groups at risk are women, infants and children respectively. Iron is an important raw material for the synthesis of hemoglobin, and when the stored iron in the body is depleted, the synthesis of hemoglobin will be impaired. Patients may experience varying degrees of dizziness, weakness, fatigue, tinnitus, shortness of breath after activity, tachycardia, loss of libido, and in severe cases, ectodermal nutritional disorders such as stomatitis, tongue inflammation, atrophic gastritis, dry skin, dry hair loss, brittle and cracked nails. So, where does iron come from? And where does it go? Iron comes from exogenous iron absorbed from the intestine and endogenous iron released from aging red blood cells. About 80% of the iron released from senescent red blood cells can be recycled, while the main sites of iron absorption from a balanced general diet are in the duodenum and upper jejunum. The normal human body does not have physiological iron excretion except for menstruation and loss of iron by epithelial cell shedding. Therefore, iron deficiency anemia generally does not occur if there is sufficient iron intake in the diet, no excessive menstruation or other blood loss, especially long-term chronic blood loss, and no absorption disorders. Among patients seen for iron deficiency anemia, excessive menstrual flow due to uterine fibroids, intrauterine device and menstrual disorders are the most common causes. Other causes include chronic bleeding hemorrhoids, inadequate iron intake due to dieting and partial dieting, absorption disorders due to total or partial gastrectomy, long-term use of H2 receptor antagonists or proton pump inhibitors for gastric ulcers, low gastric acid, chronic diarrhea, and Helicobacter pylori infection. It is worth to be alerted that iron deficiency anemia is often the first manifestation of gastrointestinal tumors. Patients are seen for anemia symptoms, and doctors find that patients have chronic gastrointestinal bleeding when they rank the causes of anemia, and then further examination reveals that the cause of chronic gastrointestinal bleeding is gastric or intestinal cancer. Therefore, after the diagnosis of iron deficiency anemia, never forget to check the cause of iron deficiency to avoid missing the tumor. The treatment is of course to replenish enough iron and at the same time to remove the cause of iron deficiency, especially digestive tract tumors need to be diagnosed and treated promptly. Iron supplementation can be administered orally or intravenously, with oral iron preferred. Ferrous succinate and ferrous sulfate are recommended. The former has high iron content, good absorption, high bioavailability and low adverse effects, while the latter is the standard preparation among oral iron supplements, but has a large gastrointestinal reaction. When taking iron, avoid taking it with tea, calcium salt and magnesium salt. After treatment until the hemoglobin returns to normal, it is necessary to continue treatment for 3 months, otherwise it is easy to relapse. The incidence of adverse reactions to intravenous iron is 13% to 26%, so it is limited to patients who cannot tolerate oral iron, or who have impaired absorption, or who are on long-term hemodialysis or have functional iron deficiency. What about megaloblastic anemia? Megaloblastic anemia caused by folic acid and vitamin B12 deficiency is the most common vitamin deficiency worldwide. In China, folic acid deficiency is predominant; vitamin B12 deficiency is higher in the elderly population and increases with age. Folic acid is a water-soluble B vitamin and is most abundant in fresh green leafy vegetables, as well as in liver, kidney, yeast and mushrooms, but can be destroyed by cooking, pickling and long storage of food. Folic acid is only 5-10mg stored in the human body, and the recommended daily intake for adults is 400μg, with higher demand from pregnant and lactating women, so insufficient intake is prone to deficiency. Vitamin B12 is a cobalt-containing vitamin, which is mainly taken from animal foods such as meat, liver, fish, eggs and dairy products, etc. The amount of vitamin B12 stored in the human body is 2~5mg, while the recommended daily intake for adults is only 2.4μg, and 2.6 and 2.8μg for pregnant and lactating women. Therefore, the number of deficient people is less than that of folate deficient people. Folic acid deficiency can be caused when there is an increased need for folic acid in pregnancy, breastfeeding, infants, children, as well as in chronic hemolysis and hyperthyroidism, or when there is malabsorption of folic acid from alcoholism, alcoholic cirrhosis, intestinal diseases, etc. Some medications such as methotrexate, salbutamol, and antiepileptic drugs can induce folic acid deficiency. Vitamin B12 deficiency can be caused by long-term strict vegetarian diet, pregnancy, breastfeeding, increased needs of infants and children, atrophic gastritis in the elderly, gastric acid deficiency, long-term use of drugs that inhibit gastric acid secretion, major gastric resection or total gastrectomy, small intestinal diseases that affect absorption, and some drugs such as metformin. Folic acid and vitamin B12 deficiency can cause megaloblastic anemia, leukopenia and thrombocytopenia, as well as loss of appetite, bloating, diarrhea, tongue inflammation and other gastrointestinal symptoms, tongue inflammation manifested as red tongue, tongue papillae atrophy, smooth surface with pain, commonly known as “beef tongue”. Vitamin B12 deficiency can also cause weakness, hand and foot numbness, sensory impairment, walking difficulties and other peripheral neuritis, subacute or chronic posterior spinal cord joint degeneration and other neurological manifestations, the elderly often mistakenly think they are “small stroke” and go to the neurology department. Some pediatric and elderly patients may also present with psychiatric symptoms such as anhedonia, drowsiness, or confusion. If a patient has the above clinical manifestations of megaloblastic anemia, routine blood tests reveal anemia or a decrease in white blood cells and platelets, a mean red blood cell volume (MCV) greater than 110 fl, and a mean red blood cell hemoglobin content (MCH) greater than 32 pg, further serum folate and vitamin B12 measurements should be performed and the cause analyzed. Treatment is based on the principle of “what is lacking is what is needed”. Folic acid deficiency can be treated with oral folic acid, while vitamin B12 deficiency can be treated with intramuscular injection of vitamin B12 and methylcobalamin. Some people with vitamin B12 deficiency require lifelong maintenance therapy with a maintenance dose of 1000 μg of vitamin B12 intramuscularly once a month. The same care should be taken to remove the cause of the disease. Therefore, with better conditions and more food choices, it is also important to “eat” and to correct partial eating habits and incorrect cooking habits. For patients with total or major gastric resection, long-term use of anti-epileptic drugs, acid control drugs, prophylactic oral administration of folic acid or vitamin B12 is required. reminder, iron should not be taken arbitrarily to avoid iron overload of the body.