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Nutrition Column

Where did that water recommendation of 8 cups per day come from anyway? And is it right?

Most of us have heard the old adage “drink eight glasses of water every day”. But exactly where the saying came from and whether or not it is right for most of us is not clear. The earliest recommendation for water came in the 1945 prescription by the Food and Nutrition Board of the National Research Council. It was based on research at the time suggesting an intake of “1 ml. of water for each calorie eaten”, or about 8 cups a day.

The latest recommendation for water intake of the National Academies’ Institute of Medicine (Feb. 2005), which is based on over 400 studies,lists 72.8 ounces (nine 8-ounce glasses) of fluid for women and 100 ounces (12.5 8-ounce glasses) of fluid for men.

Yet, dependent on your diet much of the water you need may actually come in the foods you eat and the other beverages beside water you drink. Remember, most of us get over 20 percent of our water needs from the foods we eat and the rest must come from our drinks -milk, juice, soda, and coffee included!

While water is an essential nutrient, aiding in numerous bodily functions, we can derive a lot of our requirement from our food. Most foods, other than oils and dry grain products, contain greater than 50 percent water. And not just those with water in their name - although those as expected are high.

Note that even rice and pasta, while quite dry in their uncooked state are relatively high in water when prepared “al dente”. Here is a brief list of the water content, in percent, in a half cup serving of the following foods:

As you can see, it is possible to get a good amount of water from the foods you eat, not to mention the water in the liquids you consume other than water itself. And it all counts!! Even from caffeinated beverages, including coffee.

Caffeine, once thought to be a potent diuretic has undergone a new look. Several recent scientific studies, including one published in 2000 in the Journal of the American College of Nutrition,have found that caffeine and coffee promoted no greater diuretic or dehydrating effect than diet soda, decaffeinated coffee or water.

And one last thing about the color of your urine, “should it be clear”. And is clear urine an indication of adequate water intake. Actually, constantly clear urine can actually be a sign of drinking too much water, which can dilute your body’s electrolytes. This can potentially be deadly! In addition, if your flow is unusually cloudy or dark you should see your physician to rule out any health problems, but some color is normal and healthy. As you may already know - water soluble vitamins in food or supplements, particularly the B Vitamins, can deepen the color of your urine.

Written by Dr. Sternlicht for on 09.01.05