Immunocompetence and trace element nutrition : a critical review : A dissertation submitted in partial fulfilment of the requirements for the degree of Master of Applied Science at Lincoln University

Abstract

Immunocompetence is a state in which the immune system is functioning at its potential. A lot of environmental factors influence the ability of the immune system to do this including trace element nutrition. Trace elements promote immunocompetence as essential components of enzymes, in a protective way and as pharmacological substances. Zinc deficiency results in increased incidence of diarrhoeal disease. Increased severity and length of parasitic infections and impairment of the immune system also occur during zinc deficiency. The availability, metabolism and diagnosis of trace element responsive disorders highlights the complexity of determining if trace element status is affecting immunocompetence. Adequate selenium is vital to normal neutrophil function due to selenium role as an antioxidant. Inadequate selenium and vitamin E in the diet increase the incidence and severity of mastitis. Mastitis is used as a model of immunoincompetence as the many different causes of mastitis infection allow some illustration of the vastness of the relationship between selenium and immunocompetence. Neutrophils play an important role in mastitis infections. The severity and frequency of mastitis infections is correlated with selenium and or vitamin E status. Selenium's role as an antioxidant has been identified as perhaps the major contributing factor to immunocompetence from selenium. Copper deprivation results in a reduction in the ability to mount a normal immunological response. The mechanisms of coppers role in immunity are somewhat unclear with superoxide dismutase and iron binding providing only part of the answer. It is hoped that this review of immunocompetence and nutrition will set the scene for encouraging in-depth studies of specific trace element and immune relationships.