Nutrition and Immune Function

Karen S. Geismar, MS, RD, LD, CNSC Lecturer, Department of Nutrition and Food Sciences

Texas A&M University
College Station, TX

October 3, 2014


The role of nutrition in hospital recovery cannot be stated too strongly. Nutrition plays a premier role in a strong response system to the ravages of infection on the body. The immune system, which is the body's defense mechanism against infection, relies intricately on how well the body is nourished. Marginal nutritional status leaves a person more susceptible to infections and less able to fight off any foreign invaders. Malnutrition is the result of inadequate or excess protein, calories, and/or micronutrients, which may be indicated by abnormal blood chemistries, loss of lean body mass or gain of adipose tissue, and/or impaired organ function.1,2If left untreated, malnutrition can lead to increased morbidity and mortality. Undernutrition may be characterized by deteriorated functional ability and poorer clinical outcomes that usually occur when weight loss exceeds 10 to 20 percent of pre-illness body weight. Overnutrition is associated with increased risk of chronic conditions and altered immune function.3,4Despite the most advanced laboratory and assessment tools available for nutritional assessment, there is no single test that is both sensitive and specific for malnutrition.5Diet and weight history and physical exam for loss of lean body mass may be a more sensitive indicator. Malnourished medical and surgical patients have more complications (e.g., slower healing, increased incidence of infection, and multiple organ failure) than do those who are well nourished. Consequently, they have longer hospital stays and increased mortality rates, and they incur higher medical costs. Medical nutritional therapy must be considered along with drug interventions in the patient care plan for recovery from the infection process.