There are many so-called "micronutrients" that are required in the human diet. Many of these are metals including Sodium, Potassium, Zinc, Cobalt and Iron. Iron plays a special role since it is a member of the transition state elements and can assume a number of different charged states; this attribute has made it quite useful as an essential cofactor in the function of many enzymes and oxygen transport systems not only in humans but also in many diverse life forms across the entire spectrum of living things.
On account of these properties, iron has been shown to play an important role in host-pathogen interactions during infections. As a matter of fact, it has been clearly shown that a host's iron status can directly impact the degree and intensity of infection. In one particular study involving Somalis who were iron-deficient, these individuals had a five-fold increase in various infections including reactivation of preexisting malaria in relation to those individuals that were given iron supplements. A degree of caution needs to be stressed in regards to the ingestion of iron supplements in that excessive intake can prove toxic.
A hormone, Hepcidin, present in humans has been shown to play a key role in the absorption of iron consumed in the diet and its subsequent distribution to many tissues throughout the body. In addition, Hepcidin, a peptide hormone (peptides are small protein molecules), has antimicrobial properties.
Dr. Hal Drakesmith and his colleagues from the Molecular Immunology Group and Medical Research Council Human Immunology Unit at the Weatherall Institute of Molecular Medicine at the University of Oxford in Oxford, UK, have shown that the synthesis of Hepcidin is regulated by not only the levels of iron present in the body but also immunological status i.e. the presence of infectious agents.
Another aspect of iron regulatory mechanisms relates to the presence of unbound iron or heme – that is often released during infections – in the circulation. Unbound iron can have a number of deleterious side effects:
· It can provide an essential nutrient to an ongoing infection
· It can generate harmful free radicals and result in tissue damage.
For these reasons, there are proteins present that can safely bind the unbound iron. These proteins include transferrin, lactoferrin and ferritin for iron; haptoglobin for hemoglobin – the essential component for delivering oxygen to the tissues- and hemopexin for heme. The antimicrobial properties of these iron carriers is supported by the observation that they inhibit the growth of certain bacteria in the laboratory and by the fact that lactoferrin is found in abundance in breast milk and is released from neutrophils – immunological cells that are involved in the body's first line of defense against infection.
These data strongly implicate iron status in the body with good health and the natural defense against infection.