The prevalence and causes of anaemia among the inhabitants of a Southern Lebanese village were studied. Of the 317 patients examined 75, or 24% were found to be heterozygotes for Hb S. There was a reciprocal relation between the presence of
sickle cell trait and of
iron deficiency anaemia. The prevalence of
iron deficiency anaemia defined as the coexistence of Hb below 13 g/dl in adult males and below 12 in adult females and children with two laboratory indicators of
iron deficiency, was 10.3% in the normal population as against 1.3% in the
sickle cell trait group (P less than 0.008). The reduced frequency of
iron deficiency anaemia in
sickle cell trait may be explained by increased
iron absorption, or alternatively by reduced
iron requirements and a lower risk of discrepancy between
iron supply and demand. Because of the central role of
iron in the function of a great number of
enzymes and
proteins, it is possible that protection against
iron deficiency anaemia by the
sickle cell trait may result in improved working capacity and a lower incidence of
infections.