Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues. There are many types of anemia. Iron deficiency anemia is a decrease in the number of red cells in the blood caused by too little iron.

See also: Iron-deficiency anemia - children

Iron deficiency anemia is the most common form of anemia. About 20% of women, 50% of pregnant women, and 3% of men do not have enough iron in their body.

Iron is a key part of hemoglobin, the oxygen-carrying protein in the blood. Your body normally gets iron through diet and by recycling iron from old red blood cells. Without iron, the blood cannot carry oxygen effectively. Oxygen is needed for every cell in the body to function normally.

The causes of iron deficiency are:

• Blood loss (including from heavy menstrual bleeding)
• Poor absorption of iron by the body
• Too little iron in the diet

It can also be related to lead poisoning in children.

Anemia develops slowly after the normal iron stores in the body and bone marrow have run out. In general, women have smaller stores of iron than men because they lose more through menstruation. They are at higher risk for anemia than men.

In men and postmenopausal women, anemia is usually caused by gastrointestinal blood loss from:

• Certain types of cancer (esophagus, stomach, colon)
• Long-term use of aspirin or nonsteroidal anti-inflammatory medications (NSAIDS)
• Peptic ulcer disease
• Ulcers

Iron deficiency anemia may also be caused by poor absorption of iron in the diet, due to:

• Celiac disease
• Crohn's disease
• Gastric bypass surgery
• Taking antacids

High-risk groups include:

• Infants, children, and adolescents who are growing quickly
• People who do not get enough iron in their diet
• People who use aspirin, ibuprofen, or other arthritis medicines long-term
• Pregnant or breastfeeding women who need extra iron
• Seniors
• Women of child-bearing age who have lost blood through heavy menstrual periods