Iron deficiency causes a characteristic anemia with small pale red blood cells, deficient in oxygen-carrying hemoglobin. Iron supplementation cures this anemia, and is one of the more gratifying treatments in the medical repertoire. Iron is stored in the bone marrow, and once full, can supply enough iron for several months of dietary iron deficiency. Women store less iron than men, and lose iron monthly in menstrual blood, and are therefore much more likely to suffer iron deficiency than men. Both breast milk, and cow's milk need iron supplementation, after 4 months.
Absorption is enhanced by VM.C, fish, and meat.
Iron deficiency is routine in patients with inflammatory bowel disease, especially Crohn's disease. Injection of iron into buttock muscles is often necessary when iron absorption is blocked by a diseased small intestine. Marginal iron deficiency, before the appearance of anemia, can impair exercise tolerance via malfunction of iron-using enzymes in the energy system. Increased lactic acid production with exertion is one of the markers of subtle iron deficiency. Iron intake of athletes should be carefully monitored.