Single nutrients and immunity

Abstract

Abstract : Soon after their discovery, vitamins were recognized for their importance in host resistance against infectious illness. Vitamins and other single nutrients were also shown to influence host immunological functions. It subsequently became evident that generalized forms of severe malnutrition, i.e., kwashiorkor and marasmus, were often accompanied by problems of anergy. Such nutritionally induced immunological defects are acquired rather than inherited, are largely functional, and are generally eliminated when the nutritional deficits are corrected. Clinical awareness of this problem has increased, with a primary focus on problems seen during generalized protein and energy deficiencies. Although inherited immunodeficiency disorders attract most interest among clinical immunologists, the prevalence of inherited immune defects is low. In contrast, acquired immunodeficiencies due to malnutrition are common in impoverished populations throughout the globe. Functional anergy may also emerge as a secondary consequence of malnutrition during severe or protracted medical and surgical illnesses. Severe protein-energy malnutrition (PEM) does not generally occur without concomitant deficiencies of one or more micronutrients. However, relatively little effort has been expended to determine the role of single nutrients in influencing immune system functions. Few reviews even mention this point. Because of the potential clinical importance of single nutrient deficits or excesses on immune system functions, a workshop was sponsored by the Food and Nutrition Board of the American Medical Association. The workshop served to emphasize the diversity of the subject, the magnitude of unsolved problems, and the complexity of interrelationships requiring consideration. Major gaps currently exist in knowledge about single nutrient deficits or excesses in terms of their effects on specific functional components of the immune system.