Chapter 45: Nutrition and Metabolic Health

Nutrition and Metabolic Health begins by defining the biochemical units of nutrition, categorizing nutrients into macronutrients such as carbohydrates (simple and complex), proteins (essential for nitrogen balance and tissue building), and fats (saturated, unsaturated, and essential fatty acids), alongside regulatory micronutrients including fat-soluble and water-soluble vitamins and minerals. The text details the anatomy and physiology of the digestive system, explaining how mechanical and chemical digestion break down food into chyme, followed by absorption through the intestinal villi via mechanisms like active transport and osmosis, and concluding with metabolic processes involving anabolism and catabolism. Nutritional requirements are contextualized through standard guidelines such as the Dietary Reference Intakes (DRIs) and the USDA MyPlate program, while also addressing environmental and developmental factors ranging from the high metabolic needs of infancy to the physiological changes in older adults. The nursing process is applied to nutrition through detailed assessment strategies, including dietary history, anthropometry (Body Mass Index and Ideal Body Weight), and laboratory testing for albumin and nitrogen balance. Significant attention is given to identifying and managing malnutrition and dysphagia, with specific protocols for aspiration precautions. The chapter thoroughly describes clinical interventions for patients unable to ingest food orally, contrasting Enteral Nutrition (EN)—administered via nasogastric, gastrostomy, or jejunostomy tubes—with Parenteral Nutrition (PN), which delivers nutrients intravenously through central lines. It outlines safety procedures for verifying tube placement, such as pH testing and x-ray confirmation, and managing potential complications like refeeding syndrome or catheter-related sepsis. Finally, the discussion covers Medical Nutrition Therapy (MNT), detailing therapeutic diets for managing specific disease states including gastrointestinal disorders (peptic ulcers, inflammatory bowel disease, celiac disease), Diabetes Mellitus, cardiovascular diseases requiring sodium and fat restrictions, and the distinct nutritional support required for patients with cancer or HIV/AIDS.