& Joannie Dobbs Saturday
January 27, 2007
Make sure you consume enough water
True or false? Water is the most important nutrient for the human body. A good argument can be made for "True." Although all essential nutrients are required for normal body functions, the body can become deficient in water more quickly than with any other nutrient.
Question: Why is water so important for the body?
Answer: About 50 to 60 percent of the human body is water. Virtually every biochemical and physiological function in the body is dependent on the presence of an adequate amount of water.
Q: Does low water intake affect body functions?
A: The body has the ability to adapt to limited water intake by reducing urine output. However, some studies indicate that there is a cost if a person's state of hydration declines by even 2 percent of body weight. That's about 48 ounces, on average.
Both physical and mental performance are adversely affected. Studies have reported impaired short-term memory, poor attention and decreased math ability. Other health problems linked to low water consumption include an increased chance of developing urinary tract infections, kidney stones, bladder and colon cancers, and possibly blood clots.
Q: Is it necessary to drink plain water?
A: No. There are many ways to get enough water from a combination of foods and beverages. The Institute of Medicine recommends that the average man drink about three liters (about 12 cups) of beverages a day and estimates that they will get about three-fourths of a liter of water from their food. For the average woman, the recommendation is just more than two liters a day from beverages, with about half a liter from food.
In addition to pure water, the beverages can include most any liquids. Even coffee and tea are OK, with studies indicating that caffeine only has temporary effects on increased urine loss but has little effect on overall daily hydration.
Q: Can you drink too much water?
A: It is possible. People have died from hazing incidents, and recently a woman died from a water-drinking contest. The woman reportedly drank about seven liters in a short time. The kidneys can only dispose of about a liter of excess water per hour. Unfortunately, the rest of the water overly diluted body fluids and resulted in fatal water intoxication.
Alan Titchenal, Ph.D., C.N.S. and Joannie Dobbs, Ph.D., C.N.S.
are nutritionists in the Department of Human Nutrition, Food and Animal Sciences,
College of Tropical Agriculture and Human Resources, UH-Manoa.
Dr. Dobbs also works with the University Health Service
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