Malnutrition in Adults
Tommy Cederholm, M.D., Ph.D., and Ingvar Bosaeus, M.D., Ph.D.
Malnutrition is an imbalance between the growth and breakdown of body tissues and nutrient stores, resulting in loss of muscle and organ mass, diminished physical and mental functioning, and impaired clinical outcomes. Over the past 50 years, malnutrition has been increasingly recognized as a deleterious consequence of chronic and acute disease. On the basis of the cause of malnutrition, three subtypes are recognized: disease-related malnutrition in the absence of underlying inflammation, disease-related malnutrition with underlying inflammation, and starvation due to inadequate access to food (i.e., food insecurity) (Fig. 1).1,2 Pathophysiology The concept of two major pathophysiological pathways of malnutrition is well established. The inflammation-related pathway results from anorexia and increased tissue breakdown, and the deficiency-related pathway is initiated by decreased intake or absorption of food and nutrients (Fig. 2).1,2 Energy and Nutrient Deficiencies Inadequate intake or absorption of energy and nutrients is the classic scenario of malnutrition. Dysphagia after stroke and short bowel syndrome are examples of this noninflammatory pathway. Under such conditions, human metabolism adapts by decreasing resting energy expenditure, heart rate, body temperature, and spontaneous physical activity. Glycogen stores in the liver and muscles are depleted within 1 to 2 days and replaced by body fat as the main energy source. Protein stores are partially protected, but muscle is still depleted to ensure a supply of amino acids for protein synthesis and oxidation for energy. This adaptation contributes to the ability to survive starvation. Historical observations indicate that survival for up to 60 days in a state of complete starvation is possible if fluids are available.
LEGGI TUTTO https://www.nejm.org/doi/full/10.1056/NEJMra2212159#:~:text=DOI%3A%2010.1056/NEJMra2212159
