A deficiency of iron is the most common nutritional cause of anemia. Iron is essential for making hemoglobin, the protein inside red blood cells that binds oxygen in the lungs and carries it to tissues throughout the body.
When the body’s iron supply falls, it first uses stored iron. Continued deficiency eventually limits hemoglobin production, producing iron-deficiency anemia. The resulting red blood cells are typically smaller and contain less hemoglobin than normal. Common symptoms can include tiredness, weakness, dizziness, shortness of breath, and reduced concentration.
Low intake is one possible cause, but iron deficiency can also result from blood loss, poor absorption, or increased needs during growth and pregnancy. Heavy menstrual bleeding is a frequent risk factor, while gastrointestinal bleeding is an important cause in many adult men and postmenopausal women.
Iron is not the only nutrient linked to anemia. Folate and vitamin B12 deficiencies can also impair red blood-cell production, and infections, inflammation, inherited disorders, and chronic disease can cause anemia without an iron deficiency. That is why the underlying cause should be identified rather than assuming every anemia requires iron supplements.