Phosphorus: Basic Nutritional Aspects

Phosphorus is one of the most abundant minerals in the body, with the majority of it stored in bone and teeth. Maintenance of extracellular and intracellular phosphate levels within a narrow range is important for many biological processes, including energy metabolism, cell signaling, regulation of protein synthesis, skeletal development, and bone integrity. Three major mechanisms are responsible for the maintenance of systemic phosphate homeostasis: intestinal uptake, retention or release from the bone, and renal reabsorption. The currently known main regulators of phosphate homeostasis include parathyroid hormone, vitamin D, fibroblast growth factor-23, and Klotho. Growth, aging, and genetic and metabolic disorders can all significantly alter systemic phosphate balance. The recommended dietary allowance, 700. mg/day of phosphorus for healthy adults, is meant to maintain serum phosphorus concentrations within the physiologic range of 2.5-4.5. mg/dL. Along with additives in processed foods, dietary sources of phosphorous include meat, poultry, fish, eggs, dairy products, beans, and seeds, and nutritional phosphate deficiency is uncommon. However, several clinical disorders may affect intestinal or renal phosphate (re)absorption and contribute to hyper- or hypophosphatemia. Patients with chronic kidney disease, with renal failure, and/or on dialysis benefit from reduced phosphorus intake. In this chapter we provide a brief review of the physiological and nutritional aspects of phosphorus as well as key factors involved in the maintenance of its homeostasis, and we outline disorders associated with pathophysiological changes in systemic phosphate balance.