Practices... - Healthy Diet - Water

Your body is composed of approximately 70 percent water and accounts for one-half to four-fifths of your weight. The average adult body contains forty-five litres of water. Thirty of these litres, referred to as intracellular fluid, circulate within cells and there is a constant exchange of intra and extra-cellular fluid through cell membranes. Three litres circulate as blood plasma, carrying protein and other nutrients that pass through capillary walls. The remaining twelve litres, referred to as interstitial fluid, surround cells and are found in lymph and various other secretions.

Water is required by all body tissues and is used by all joints, organs, and systems. It is essential for all body functions and an increased water intake generally enhances these processes. Water acts as a solvent for vitamins, minerals, amino acids, glucose, and a number of other nutrients and plays a role in the digestion, absorption, transportation, and utilization of these nutrients. It is the base of all blood and fluid secretions, including gastric juices, saliva, synovial fluid, tears, and others. Water also acts as a cushion for body cells and surrounds the developing fetus, in the form of amniotic fluid.

Increased water intake hydrates your cells, enhances organ function, improves the efficiency of your lymphatic and elimination systems, maintains acid-alkaline balance, improves mental and physical performance, lubricates joints, maintains proper internal temperature, promotes healthy skin and generally makes you feel better.

You typically require 1.9L/2 quarts water daily to support proper function. Approximately 0.9L/1 quart is obtained through food while an additional 0.9L/1 quart must be consumed separately. This quantity increases for physically active people or those living in warmer climates. Serious dehydration can occur with a loss of only 5 to 10 percent body water, while a 15 to 20 percent loss is often fatal.

As we age, we "dry-out" somewhat and lose our desire for thirst. While a newborn is 75 to 80 percent water, people between the age of 65 and 70 are typically composed of only 50 percent water. This is reflected in stiff joints and reduced saliva flow. For this reason, optimal water consumption is recommended throughout life and well into the retired years.

When internal water content decreases, blood volume drops, salt content slightly increases, and saliva production drops. This series of events triggers a chemical and hormonal process inducing a sensation of thirst that is relieved through the consumption of water or other fluids. When you are thirsty, your kidneys also conserve water by redirecting it back into the bloodstream, resulting in increased urine concentration.

For more information, see the dedicated section on Water.