Why is proper hydration so important for good health?
Water, being the most abundant molecule on the earth’s surface, is often called the ‘universal solvent’ due to it’s ability to dissolve a wide variety of substances in it.
The human body can contain up to 75% water in very young children, though most commonly in adults the figure is around 60%. As we age, our bodies contain less and less water, dehydrating with age. Obesity also decreases the percentage of water in the body, as fat contains only 10%.
Water fulfills many functions within the human body. It is a solvent, a reaction medium and reactant. It carries nutrients to the cells and waste products away. It comprises 70% of the volume of blood, maintaining an appropriate blood pressure and viscosity so that the blood can be pumped throughout the blood vessels. Water is involved in the regulation of body temperature, as it is the evaporation of water from our bodies when we sweat that cools us down. Water is a lubricant within all tissues of the body and a shock absorber. Water facilitates the electrical conduction of nerve impulses between the cells and it acts as a building material.
Whilst a healthy human adult can regulate water balance rapidly and with great precision, resolving a 1% loss of body water within just 24 hours, the very young, the elderly and those in poor health are not as responsive to the minuet changes in plasma osmolarity which trigger the body to control it’s water intake and output systems and therefore are far more susceptible to dehydration.
When the body becomes dehydrated it can affect one’s level of consciousness, causing incoherence of speech, headaches, weakness in the limbs, drops in blood pressure and a dangerously fast heart rate as the heart struggles to keep the blood pressure up. The eyeballs can even lose their tone as they are almost completely water.
A study by researchers in the Department of Physiology at the University of Lausanne in Pully, Switzerland recently published a paper on the importance of hydration with water (as opposed to tea, coffee, juice and other liquids) summing up that “The regulation of water balance is essential for the maintenance of health and life. On an average, a sedentary adult should drink 1.5 l of water per day, as water is the only liquid nutrient that is really essential for body hydration.”
The water requirements of each individual will be different, depending upon their level of activity, environment and state of health. A sedentary office worker may require as little as 1.5 liters per day, whereas a construction worker in a hot, outdoor environment may require several liters. The factors that influence our need for water include climate, level of exertion, diet and state of health.
E Jéquier and F Constant. Water as an essential nutrient: the physiological basis of hydration Eur J Clin Nutr 2010 64: 115-123; advance online publication, September 2, 2009; 10.1038/ejcn.2009.11 http://www.nature.com/ejcn/journal/v64/n2/full/ejcn2009111a.html