Why does iron deficiency lead to anemia?

Every nutrient in our body is very important. They play a huge role in our body. Once a certain element is lacking, we will suffer from a certain disease. Especially iron deficiency, which may lead to anemia. The impact on life is enormous. So, why does iron deficiency lead to anemia? What is the cause of iron deficiency anemia?

Increased iron requirements and insufficient iron intake:

Children's iron requirements increase during the growth period and infant breastfeeding period, especially premature infants, twins or mothers with anemia. The original iron reserves of infants are insufficient. If they are only fed with human milk with less iron, and are not supplemented with iron-rich supplementary foods such as eggs, green vegetables, meat and animal liver in time after teething, iron deficiency anemia can occur. The iron requirement increases during pregnancy and lactation, and the gastrointestinal dysfunction and lack of gastric acid during pregnancy affect iron absorption, especially after multiple pregnancies, which can easily cause iron deficiency anemia. Adolescents need more iron due to rapid growth, especially young women. Due to menstrual blood loss, iron deficiency may also occur if the food they eat for a long time lacks iron. The most common reasons are insufficient iron content in food, picky eating or malabsorption. Heme iron in food is easily absorbed and is not affected by food composition and gastric acid, while non-heme iron needs to be converted into Fe2 before it can be absorbed. Phosphates, phytic acid and tannins in vegetables, cereals and tea can affect iron absorption.

The daily iron requirement for adults is about 1 to 2 mg. 1 mg/d is enough for men. Women of childbearing age and growing adolescents need more iron, which should be 1.5 to 2 mg/d. If the diet is rich in iron and the body has sufficient iron storage, iron deficiency rarely occurs.

Other reasons for insufficient iron intake are drugs or gastrointestinal diseases that affect iron absorption, the intake of certain metals such as gallium and magnesium, calcium carbonate and magnesium sulfate in antacids, H2 inhibitors taken during ulcer disease, etc., which can inhibit iron absorption. Atrophic gastritis, reduced gastric acid after gastric and duodenal surgery affecting iron absorption, etc. are all causes of insufficient iron intake. In addition, the average blood loss during pregnancy is 1300ml (about 680mg iron), which requires 2.5mg of iron supplementation per day. In the last 6 months of pregnancy, 3-7mg of iron is needed per day. The iron requirement during lactation increases by 0.5-1mg/d. Insufficient supplementation will lead to a negative iron balance. If there are multiple pregnancies, the iron requirement will increase. Each time a blood donor donates 400ml of blood, it is equivalent to a loss of 200mg of iron. About 8% of male blood donors and 23% of female blood donors have reduced serum ferritin. If blood is donated multiple times in a short period of time, the situation will worsen.

Excessive depletion of stored iron:

Since 2/3 of the total iron in the body is present in red blood cells, repeated and excessive blood loss can significantly consume the body's iron reserves. Hookworm disease causes chronic small-scale intestinal bleeding, repeated bleeding from upper gastrointestinal ulcers, many years of anorectal bleeding, or excessive menstruation in women and other long-term losses will eventually lead to insufficient iron reserves in the body, resulting in iron deficiency anemia. In addition, paroxysmal nocturnal hemoglobinuria, mechanical hemolysis caused by artificial mechanical heart valves, and idiopathic pulmonary hemosiderosis can all cause anemia due to long-term iron loss in the urine. Normal people lose about 1 mg of iron from the gastrointestinal tract, urinary tract and skin epithelial cells every day. Women lose more iron during menstruation, childbirth and breastfeeding. Clinically, excessive iron loss in men is often due to gastrointestinal bleeding, while in women it is often due to excessive menstruation.

Excessive loss of free iron:

Free iron can be lost as the gastrointestinal epithelial cells age and continue to fall off. In atrophic gastritis, subtotal gastrectomy and steatorrhea, the epithelial cell renewal rate is accelerated, so the loss of free iron also increases. Iron deficiency not only causes a decrease in heme synthesis, but also reduces the activity of iron enzymes (such as cytochrome oxidase) in red blood cells, affecting the electron transfer system, which can cause abnormal lipid, protein and sugar metabolism, leading to abnormal red blood cells, which are easily destroyed in the spleen and shorten their life span. The iron in the human body is in a closed cycle. Under normal circumstances, the absorption and excretion of iron maintain a dynamic balance. The human body generally does not lack iron. It is only when the need is increased, insufficient iron intake, chronic blood loss, etc. that cause a long-term negative iron balance and lead to iron deficiency. The causes of iron deficiency can be divided into two categories: insufficient iron intake and excessive loss.

In fact, iron deficiency anemia is very easy to prevent, but people just don’t pay attention to it. The prevention of this disease should start from an early age, especially for babies at home, who must do a good job of prevention. Be sure to breastfeed, add some iron supplements to the baby's food, and promptly prevent gastrointestinal bleeding and other diseases.