Intestinal transport during fasting and malnutrition

Fasting or malnutrition (FM) has dramatic effects on small intestinal mucos al structure and transport function. Intestinal secretion of ions and fluid is increased by FM both under basal conditions and in response to secretor y agonists. Intestinal permeability to ions and macromolecules may also be elevated by FM, which increases the potential for fluid and electrolyte los ses and for anaphylactic responses to luminal antigens. Mucosal atrophy ind uced by FM reduces total intestinal absorption of nutrients, but nutrient a bsorption normalized to mucosal mass may actually be enhanced by a variety of mechanisms, including increased transporter gene expression, electrochem ical gradients, and ratio of mature to immature cells. These observations u nderscore the value of enteral feeding during health and disease.