Every intervention aiming to supplement a lacking nutrient in the body or any application of medicine should be accompanied by the question whether any such intervention could bring about any unsatisfactory changes. Many publications of medical research centres in England, Canada, USA, Sweden and Germany aim to deal with the problem posed in the title. This paper, based on studied literature, presents some important aspects concerning epidemiology, experimental studies and clinical observations on iron overload in the body, but only in cases of genetic conditioning - hereditary (primary) haemochromatosis - HH.