SYNERGISM OF NUTRITION, INFECTION, AND IMMUNITY - AN OVERVIEW

Infections, no matter how mild, have adverse effects on nutritional st atus. The significance of these effects depends on the previous nutrit ional status of the individual, the nature and duration of the infecti on, and the diet during the recovery period. Conversely, almost any nu trient deficiency, if sufficiently severe, will impair resistance to i nfection. Iron deficiency and protein-energy malnutrition, both highly prevalent, have the greatest public health importance in this regard. Remarkable advances in immunology of recent decades have increased in sights into the mechanisms responsible for the effects of infection. T hese include impaired antibody formation; loss of delayed cutaneous hy persensitivity; reduced immunoglobulin concentrations; decreased thymi c and splenic lymphocytes; reduced complement formation, secretory imm unoglobulin A, and interferon; and lower T cells and T cell subsets (h elper, suppressor-cytotoxic, and natural killer cells) and interleukin 2 receptors. The effects observed with single or multiple nutrient de ficiencies are due to some combination of these responses. In general, cell-mediated and nonspecific immunity are more sensitive than humora l immunity.