Background: Seven out of ten deaths among the world's children are caused by infectious diseases. Malnutrition is a contributing cause in more than half of the children's deaths. At present, interventions against such diseases in children are the most cost-effective way of reducing the world's morbidity and mortality.
Material and methods: This paper discusses how nutritional status affects the immune defence, and vice versa. General protein and energy malnutrition and some specific nutrients are discussed. The paper is based on review of recent literature found in Medline, and key references in the papers identified.
Results: Malnutrition is the most common cause of acquired immune deficiency in children. Malnourished children are especially prone to develop persistent diarrhoea, which in turn aggravates the nutritional status. Iron deficiency may be caused or worsened by hookworm and a number of other gastrointestinal infections. There are indications that iron deficiency in itself reduces the immune defence. Vitamin A supplements have reduced the mortality of measles and other infectious diseases. Some studies have shown reduced vertical transmission of HIV when pregnant women get vitamin A supplements. Chronic diarrhoea may cause zinc deficiency which may aggravate the diarrhoea. In areas where the general population's zinc status is marginal, zinc supplementation has reduced the incidence and duration of persistent diarrhoea.
Interpretation: The interaction between malnutrition and common infections in children causes a considerable fraction of the global burden of disease, yet so far this is not reflected in research, which mainly targets the diseases of the rich.