Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. Chapter 4 - Water

摘要

Water, which is the solvent for biochemical reactions, has physical properties (e.g., high specific heat) to absorb metabolic heat within the body. Water is also essential for maintaining vascular volume and serves as the medium for transport within the body by supplying nutrients and removing waste. In addition, cell hydration has been suggested to be an important signal to regulate cell metabolism and gene expression (Haussinger et. al., 1994). Daily water intake must be balanced with losses in order to maintain total body water. Body water deficits challenge the ability to maintain homeostasis during perturbations (e.g. sickness, physical exercise, and environmental exposure) and can affect function and health. In very unusual circumstances, excess consumption of hypotonic fluids and low sodium intake may lead to excess body water, resulting in hyponatremia and cellular edema. Despite the importance of adequate water intake, there is confusion among the general public and health care providers on the amount of water that should be consumed (Baltin, 2003), in part because of misinterpretation of previous recommendations (NRC, 1989).