Nutrition and immunity: practical applications of research findings.

Nutrition is a major determinant of host resistance. Both deficiencies and excesses impair immune responses and lead to increased risk of infection and other diseases. Changes in immunity occur early in the development of nutritional deficiency; thus immunocompetence can be used as a sensitive functional index of undernutrition and as a prognostic marker of post-operative complications. Nutritional support enhances antibody response to common immunization procedures in such populations at risk of malnutrition as the elderly.