Anemia is a blood disorder that is caused by the reduction of red blood cells in the human body. In this condition, the amount of oxygen reaching the cells of the body gets reduced due to the absence of hemoglobin (responsible for transporting oxygen to parts of the body) in the red blood cells . This reduction in red blood corpuscles (RBCs) could be caused due to a variety of factors.

Certain factors could be countered by taking medications or supplements or a change in diet and lifestyle. Some of these factors are listed below:

• Loss of blood
  Loss of blood often results in deficiency of iron and subsequent decrease in RBC count. Blood loss may be chronic or acute and it occurs due to rapid blood loss that may result from surgery, childbirth, and trauma. Other reasons for chronic blood loss may include stomach ulcers, cancer, hemorrhoids, or even something as simple as heavy menstrual bleeding.
• Damaged RBCs or hemolysis
  Due to certain diseases, the bone marrow may be damaged, resulting in the production of damaged RBCs. For example, cancers like leukemia trigger the production of abnormal white blood cells that results in a halted production of RBCs. Moreover, certain medications or incompatibility of the rhesus factor may lead to the rupture of red blood cells, causing hemolytic anemia.
• Vitamin deficiency
  Vitamin B-12 and folate present in the body are responsible for the healthy production of red blood cells. If there is a deficiency of these essential vitamins, this could result in a low RBC count and might cause conditions like megaloblastic anemia and pernicious anemia.
• Genetic
  Conditions like thalassemia or sickle cell anemia are passed down through generations by means of chromosomal aberrations. In thalassemia, the hemoglobin chains are formed incorrectly in the body, resulting in producing smaller red blood cells. In sickle cell anemia, the shape of red blood cells is altered altogether, resembling that of a crescent end of a sickle (hence the name), which could clog the blood vessels or even damage them.
• Deficiency of iron
  This is the most common form of anemia observed in people. A deficiency of iron in the body could inhibit the production of red blood cells in the bone marrow, which could be easily countered by altering the diet and taking iron supplements.
• Lack of stem cells
  The bone marrow is also responsible for the production of stem cells. Some of these stem cells are the ones that would later turn into red blood cells. A lack of stem cells in the bone marrow could cause a deficiency in RBCs and result in a condition called aplastic anemia.