Nutrition and stress

Acute illness induces major physiological responses, which favor the adapta tion of the organism to stress and injury. The metabolic response plays key roles in maintenance of vital functions and promotion of the healing mecha nisms. All the components of energy expenditure are modified, particularly the resting metabolism. The regulation of carbohydrate metabolism is also m arkedly altered. Such patients are characterized by fasting and postprandia l hyperglycemia, insulin resistance, and by a stimulation of the hepatic gl ucose production in fasted and fed states. Lipolysis and increased fat oxid ation are typically observed. Ketogenesis processes are inhibited, concurri ng to alter the adaptation to starvation. Protein turnover is stimulated wi th a preponderance of the catabolic processes, even during full nutritional support. This induces a state of resistance to feeding, leading to a progr essive depletion of the fat free mass. Such progressive tissue catabolism c annot be reversed by hypercaloric nutrition or growth factors. Specific nut rients (aminoacids, micronutrients, PUFA) may offer interesting perspective s in stimulating immunity, improving the antioxidant balance or modulating the inflammatory response.