Genetic and dietary adaptation to malaria in human populations

Plasmodial invasion places a severe oxidant stress on parasitized erythrocytes which can result in red cell damage and removal within the reticuloendothelial system or lysis, thus interrupting the parasitic cycle. The basis of a number of genetic adaptations to malaria--including the hemoglobin variants, the thalassemias, and glucose-6-phosphate dehydrogenase deficiency--is an increased sensitivity of the variant erythrocytes to the oxidant stress of plasmodial parasitization. It is suggested that dietary adaptations of traditional cusines in human populations living in areas where malaria is endemic augment this oxidant stress. It appears that there are three components of this adaptive dietary pattern in most tropical populations: the consumption of 'oxidant fuels', moderate to high iron intake, and limitation of dietary antioxidant intake or storage. It is argued that this dietary pattern maximizes iron-mediated free radical production in parasitized erythrocytes and thus provides a form of diet-mediated antimalarial prophylaxis. African pastoral populations that are heavy consumers of milk appear to manifest a different adaptive pattern involving low intakes of para-aminobenzoic acid, vitamin E, and iron. Periodic food restriction may also contribute to this antimalarial effect.