Conclusions

In spite of the numerous human and laboratory animal studies showing that many cell-mediated and non-specific immune responses are impaired in iron deficiency, the relationship between iron deficiency and infection is far less clear. Unfortunately, the issue of susceptibility to infection is very complex and depends not only on iron status, but also on many host, parasite and environmental factors (Keush, 1990). Some of these factors include exposure to microorganisms, the presence of other nutritional deficiencies, the type of population (neonates, young children, women, men, elderly), the severity and duration of iron deficiency, the type, dose and duration of iron therapy and pre-existing conditions (primary and secondary immunodeficiencies). There is no doubt that these confounding factors affect susceptibility to and severity of infection, regardless of iron status. However, based on published data, the two extremes of iron nutritional status - iron deficiency and iron overload - both have detrimental effects on cellmediated and non-specific immunity. Iron deficiency and iron overload will therefore affect susceptibility to certain types of infections, and the severity and duration of infection will vary according to host and parasite factors (extracellular versus intracellular microorganisms). In summary, oral and intramuscular iron administration of therapeutic doses to immunocompromised (malnourished) individuals is associated with increased risk of morbidity due to malaria and other infectious diseases and should therefore be avoided. In contrast, since there is no evidence of deleterious effect of oral iron supplementation to immunocompetent individuals, prevention of iron deficiency either by iron supplementation or food fortification, should remain among the priorities of public health.

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