Iron deficiency anemiaIn the United States, 20% of women of childbearing age suffer from iron-deficiency anemia, compared with only 2% of men. It can be caused by the following:
- Deficiency of iron in the diet
- An accident or trauma that causes acute blood loss
- Gradual blood loss (bleeding from the intestines or menstruation)
Other than women of childbearing age, children and teens are the next most likely to suffer from iron-deficiency anemia. And infants whose mothers experienced anemia during pregnancy are more susceptible to developing anemia.
"During an average menstrual period, it is estimated that a woman loses approximately 18 mg of iron through the loss of red blood cells," says Dr. Lark. Since iron is responsible for the production of hemoglobin, which carries oxygen, anemia may result.
Megaloblastic anemiaThis type of anemia is primarily associated with inadequate intake or utilization of vitamin B-12 and folic acid—two vitamins necessary for cell division. Thus cells that need rapid replenishment, such as blood cells, are most often affected. Fewer red blood cells are produced and anemia results.
A decreased intake of folic acid from food results in megaloblastic anemia, but pregnancy, breast-feeding and periods of rapid growth, which increase the bodies need for folic acid, also contribute. Deficiencies of iron, zinc or vitamin C will make folic acid less available to the body, and heavy alcohol consumption will increase folic acid requirements.
Vitamin B-12 is available in animal products. Thus vegetarians who consume dairy and egg products are not at increased risk for B-12 deficiency, while individuals who are strict vegans (and their breast fed infants) are most at risk for B-12 deficiency.
Aging also affects B-12 status because less acid is produced in the stomach as we age. Acid helps to release the active form of vitamin B-12 in the stomach. From the stomach B-12 travels down the intestines where it is absorbed into the body in the small intestines. Therefore people who have malabsorption are also at risk for B-12 deficiency.
Pernicious anemiaThis is another form of megaloblastic anemia caused by the absence of intrinsic factor—a chemical substance secreted by cells in the stomach that makes absorption of vitamin B-12 possible. Lack of intrinsic factor is thought to be caused by a genetic deficiency or an autoimmune disorder. A decrease in intrinsic factor is also seen in individuals with gluten (wheat, oats, rye) sensitivity or in people who have had surgery affecting parts of the small intestine. Vitamin B-12 injections are the treatment for pernicious anemia.
Pernicious anemia usually affects adults. The symptoms of this disorder come on gradually and may not be immediately recognized.
Causes of the megaloblastic anemias include:
- Inadequate intake or absorption of foods with a high folic acid or B-12 content, such as meat, poultry, fish, cheese, milk, eggs, green vegetables, yeast, and mushrooms
- Alcoholism
- Overcooking foods, which destroys folic acid
- Deficiencies of vitamin C, iron and zinc
- Low levels of acid in the stomach
- Removal of parts of the stomach or small intestine
- Gluten sensitivity
- Lack of intrinsic factor