The relationship between malnutrition and lung infections

Area of Science:

• Immunology
• Nutrition Science
• Critical Care Medicine

Background:

• Malnutrition is linked to increased infection susceptibility, particularly in developing nations.
• Protein-calorie malnutrition impairs cell-mediated immunity, antibody responses, and complement levels.
• Hospitalized patients often exhibit nutritional deficits, prompting extrapolation of findings from developing nations.

Purpose of the Study:

• To examine the relationship between malnutrition and infections in hospitalized patients.
• To evaluate the effectiveness of nutritional support on host defenses and clinical outcomes.
• To clarify the impact of malnutrition on adult antibacterial defenses in the lungs.

Main Methods:

• Review of existing literature and clinical experience from developing nations.
• Extrapolation of findings to hospitalized patients in US hospitals.
• Analysis of controlled trials on nutritional therapy, including parenteral hyperalimentation.

Main Results:

• Severe malnutrition is rare in hospitalized patients; effects on adult host defenses are less pronounced than in children.
• Controlled trials often fail to demonstrate clear patient outcome improvements with aggressive nutritional therapy.
• Lack of clear clinical endpoints complicates the interpretation of nutritional therapy's benefits.

Conclusions:

• The clinical significance of malnutrition on adult lung antibacterial defenses remains uncertain.
• Aggressive nutritional support may not be beneficial for all patients, given risks and uncertain outcomes.
• Prudent management involves aggressive infection treatment and prioritizing gut nutrition when possible.