Water is the molecular highway-allowing metabolism to take place. All of the transport of the molecules of life and their interactions occur in water. Life itself began in water. The metaphorical Biblical phrase “Living Water” is biologically correct. Sixty percent of the human body is water. To remain healthy, one must be well hydrated.
Years ago when I was an intern at the once famous but now closed Philadelphia General Hospital, elderly patients residing at a huge nursing home would become severely dehydrated and lapse into coma with very low blood pressure. In the ER, we would start an IV, run in fluid and they would soon awaken. The local-jargon diagnosis was “instant people syndrome.”
Consider the numerous ways water is lost from our bodies: obvious losses include excretions such as sweat, saliva, urine and bowel movements. Then there are the irregular losses from vomiting or diarrhea. Less appreciated are what medicine terms “insensible losses” or invisible losses. Blowing one’s breath on a windowpane, especially a cold one will cause it to fog up from the condensation of water vapor. We exhale water vapor with every breath, exhaling over a pint of water every day. Water continually evaporates from our skin without the formation of droplets of sweat. In average sized individuals, these unappreciated losses total almost four 8-ounce glasses of water a day.
The elderly are particularly vulnerable to dehydration.(Schols, 2009 #1787) Those over 65 years have decreased renal function, are often taking multiple medications, and their sensation of thirst is reduced. In a large German study, 28% of subjects 65-75 years and 41% of those over 85 years did not meet daily water intake recommendations.(Volkert, 2005 #1788)
There are a number of infirmities resulting from dehydration: decreased mental functioning, tiredness, lethargy, and cramps can occur. More seriously, dehydration predisposes to blood clots. Illnesses, especially with GI losses or fever, can increase the need for more fluid consumption.
The secret of life is “How much is enough?” A quart of total fluid intake (four (8) ounce cups) for every 50 pounds of body weight is a good rule of thumb. That amount includes beverages, water, and the fluids in food. Coffee, tea, and alcohol contain diuretics and cause more urine to be formed so they contribute to intake less than the amount consumed. It is estimated that water in food supplies and water produced by metabolism contributes 20% of our intake. Using the previous formula (Four (8)-ounce glasses of fluid/ 50 pounds body weight) and subtracting 20% a 150-pound person should consume ten (8) ounce glasses of fluid daily. Consumption of fluid should be in small amounts spread over the day, not in few large volumes or increased urine will negate the benefit.