May 31, 2013

Debunking the Eight Glasses of Water Myth

Drinking eight glasses of water a day is believed by about three fourths of adults with no reliable clinical evidence to support it.

One study on this myth was conducted in 2002 by Heinz Valtin, a Dartmouth Medical School physician and kidney specialist, who researched the subject. He believed that the statement supporting the eight glasses belief is taken from the Food and Nutrition Board of the National Research Council. It grossly misrepresented  the facts by removing facts from the original context. The sentence that followed it stated, “most of this quantity is contained in prepared foods,” which was left out and led to the false interpretation that the requirement needed to be fulfilled by drinking water alone.

After 45 years of studying the biological system that keeps the water in our bodies in balance, Valtin concluded that drinking such large amounts of water is not needed at all. He pointed out a number of published experiments that attest to the capability of the human body for maintaining proper water balance from sources other than directly drinking water which may include drinks such as tea, coffee, and soft drinks, as well as prepared foods.

Most foods have some water content. For example, apples: 85%, bean sprouts: 92%, boiled chicken: 71%, raw cucumbers: 96%, lettuce: 96%, potatoes: 85%, roast turkey: 62%, etc.

The bottom line is that the body lets us know when we need more water by making us feel thirsty. People who have specific health concerns, such as kidney stones or urinary tract infections require drinking large amounts of water. Other reasons for drinking water, such as before meals to curb an appetite is its own benefit.

Further scientific evidence also debunks the myth that by the time you feel thirsty, you are already dehydrated. A number of scientific studies have confirmed there is no support for this. Thirst hits long before we are near risk for dehydration and most folks thirst mechanism kicks in when the osmolality of the blood plasma is less than 2%, and dehydration begins at osmolalities of 5% and higher. I'll drink to that.