There are three general reasons for establishing buffer zones: to provide sanctuary, to provide a neutral area that allows for supervision where contending claims exist (in order to, potentially, facilitate cooperation), and to simply reduce tensions through separation of disputants.
Iron and immunity are closely linked: firstly by the fact that many of the genes/proteins involved in iron homoeostasis play a vital role in controlling iron fluxes such that bacteria are prevented from utilising iron for growth; secondly, cells of the innate immune system, monocytes, macrophages, microglia and lymphocytes, are able to combat bacterial insults by carefully controlling their iron fluxes, which are mediated by hepcidin and ferroportin.
You need iron to make new red blood cells. Losing iron through blood donation may affect your health. The American Red Cross now recommends that individuals who give blood on a regular basis should take a multivitamin with iron or an iron supplement to replace the iron lost with blood donation.