Protein–energy malnutrition and risk of infection

It is now well established that there is a close relation between malnutrition and infection.On the one hand, infections precipitate malnutrition and, on the other, malnutrition aggravates the outcome of many infections.Previous comprehensive reviews (Scrimshaw et al. 1968; Chandra, 1983) have examined the two-way relation between infection and nutrition emphasizing the clinical, epidemiological and experimental studies of risks associated with malnutrition.More recently the unravelling of the intricacies of the host immune response has been followed by studies of individual components of the response which are affected by nutrition (Suskind, 1977).In the majority of these reports the authors have concentrated on the severely malnourished.This has been valuable in focusing attention on the high prevalence of infection, complications of infection and death among children with marasmus and kwashiorkor.However, the majority of the world is not severely malnourished and little attention has been given to the relative risks of infection in those with milder or moderate malnutrition.It is the purpose of this paper to examine what is known, and suggest what we still need to learn, about the risks of protein-energy malnutrition (PEM), concentrating mainly on young children in underdeveloped communitiesWe have to start by defining PEM.Golden (1985) defined PEM in protein-related terms but the dietary background of an undernourished child in a disadvantaged environment is complex and a working definition of PEM can be given as 'a condition in which deficiences of major body nutrients, resulting from a diet which is generally inadequate in energy and protein, are frequently accompanied by deficiencies of micronutrients'.