Vegetarians eat less iron than non-vegetarians, and the iron they eat is somewhat less absorbable. As a result, vegetarians are more likely to have reduced iron stores.79 However, iron deficiency is not usually caused by a lack of iron in the diet alone. An underlying cause, such as iron loss in menstrual blood, often exists.
Pregnant women, marathon runners, people who take aspirin, and those who have parasitic infections, hemorrhoids, ulcers, ulcerative colitis, Crohn's disease, gastrointestinal cancers, or other conditions that cause blood loss or malabsorption are likely to become deficient.
Infants living in inner city areas may be at increased risk of iron-deficiency anemia80 and suffer more often from developmental delays as a result.81, 82 Supplementation of infant formula with iron up to 18 months of age in inner city infants has been shown to prevent iron-deficiency anemia and to reduce the decline in mental development seen in such infants in some,83 but not all,84 studies.
Breath-holding spells are a common problem affecting about 27% of healthy children.85 These spells have been associated with iron-deficiency anemia,86 and several studies have reported improvement of breath-holding spells with iron supplementation.87, 88, 89, 90
People who fit into one of these groups, even pregnant women, shouldn't automatically take iron supplements. Fatigue, the first symptom of iron deficiency, can be caused by many other things. A doctor should assess the need for iron supplements, since taking iron when it isn't needed does no good and may do some harm.