ABSTRACT
For millennia, society has recognized the critical importance of dietary intake and health. This includes protection from infection as depicted in the Four Horsemen of the Apocalypse. Malnutrition aggravates the risk of infection, and this has been documented in numerous epidemiological studies in the past 50 years. Besides poor sanitation, contaminated food and water, overcrowding, lack of knowledge of health and nutrition, and inadequate immunization, impaired immune response is a key pathogenetic factor in the malnutrition-infection interaction. This applies both to what may be called resurgent diseases, such as influenza, measles, tuberculosis, diarrhea, and respiratory infections, and to newly emergent diseases, such as HIV (human immunodeficiency virus) infection, Legionnaire’s disease, Ebola, and SARS (severe acute respiratory syndrome). It is to be emphasized that both nutrient deficiencies and excesses impair the function of the immune system and make the host vulnerable to infectious disease and other disorders (2-4). Growing data indicate that changes in nutritional immune status may have a causal role in many chronic diseases, including cancer, inflammatory bowel disease, autoimmune disorders,
Early epidemiologic studies in Asia, Africa, and South America established the relationship between overt protein-energy malnutrition (PEM) and increased incidence and severity of common respiratory and gastrointestinal infections resulting in higher mortality among young children (12). For example, in children with PEM, the incidence of diarrhea is increased by at least 40% and the duration of each episode is two to three times longer than in well-nourished controls. Similar findings have been reported for lower respiratory tract infections, both bacterial and viral.
