Final answer:
Malnutrition primarily increases infection risk by impairing immune function, hindering components like phagocyte activity and cytokine production. It also contributes to a bidirectional relationship with infectious diseases, exacerbating and being exacerbated by undernutrition.
Step-by-step explanation:
Malnutrition and Infection Risk
Malnutrition contributes to infection risk primarily by impairing immune function. This impairment can manifest through multiple mechanisms, including hindering normal gastrointestinal motility, but the direct answer to your question is that malnutrition impairs the body's immune response. This can happen due to inadequate protein intake which affects important components of the immune system such as phagocyte functionality and the production of antibodies and cytokines. The relationship between undernutrition and infectious diseases is bidirectional: undernutrition can increase the risk of infectious diseases and infectious diseases can exacerbate undernutrition, as the body may require more nutrients to fight off an infection while simultaneously struggling with reduced nutrient intake or absorption due to symptoms like vomiting or diarrhea.
The most common cause of secondary immunodeficiency worldwide is severe malnutrition, which can sometimes be reversed with proper nutritional rehabilitation. This is a critical area of study, as the impact of undernutrition on the immune system can have long-lasting effects, particularly if malnutrition occurs during important developmental stages such as childhood or even in utero.