Macrocytic anemia, also known as megaloblastic anemia, is a condition in which blood cells are abnormally large and don't function properly. It's often caused by nutritional deficiencies. These same deficiencies cause severe neurological diseases. Left untreated, they can lead to permanent neurological damage; hence the importance of early recognition and treatment.
Vitamin B12 Deficiency
B12 deficiency is the most common cause for macrocytic anemia. Vitamin B12 is essential for the function of many cells, including red blood cells. It's present in many foods from animal sources, including meat, milk and eggs. Its stores last for many years. Deficiency is usually caused by a problem with absorption. B12 is absorbed in the terminal ileum, a part of the intestines. Absorption of B12 is a complicated process that requires intrinsic factor, a protein secreted by the stomach, as well as an adequate secretion of acid by the stomach.
Factors That Cause Decreased Absorption of B12
Atrophic gastritis is a common condition in people older than 50 that causes a reduction in the size of the stomach's lining. Pernicious anemia is an autoimmune disease in which the gastric lining is attacked by the body's immune system. Gastric bypass is an increasingly common surgery that leads to a reduction in the size of the stomach's surface. All of these cause decreased production of intrinsic factor and decreased absorption of B12. Decreased acid production in the stomach and certain medications can also interfere with absorption. One example is Metformin, a widely used diabetes medication. Other, less common causes, include a vegan diet and tapeworm.
Lack of Folic Acid
Folic acid is present in many foods, mainly green vegetables and beans. It's stored in the body for only a short period. A diet deficient in folate leads to folate deficiency within several months. Alcoholism is a common reason for folate deficiency, because alcoholics substitute alcohol for real food. Pregnancy increases the need for folate, so folate supplementation is routine.
