Thursday, October 15, 2009

Water – The Myth of Eight Glasses

Water, water, everywhere….. Yes, everywhere! Everywhere people are walking around with their water, believing this is the greatest path to good health. And, to pander to this myth, authors are writing bestsellers, claiming the wonders of water.

Now, water is an essential nutrient, just as protein, fat, etc. is, however it isn’t the new, miracle anti-aging, disease prevention tool we are seeking.

I was prompted to write on water, when a person asked me last week, “What’s the most important nutrition problem people have? Not enough water, hey?” I said “No, young people are walking around with water bottles all day. That’s not our main problem. In fact, if I carried water around with me all day, I’d have to mark out the public bathrooms for stops.”

In June 1996, I wrote about the myths of water in Feel Fantastic: “Water is for weight reduction.” “Water is necessary to flush out mysterious unnamed toxins.” “Dehydration causes most of our illnesses." Who started these nonsense claims? Water is actually needed to carry essential nutrients for the healthy working of the body. It is also responsible for functions including temperature regulation and the lubrication of joints. Not for miracles.

A little more on water: Water makes up 50 to 70 per cent of the weight of the human body. Even teeth have a water content of 5 per cent. Water is the essential medium of all body fluids including digestive juices, lymph, blood, urine and perspiration. The question is how much is essential?

Logically, if we have to drink eight glasses of water per day, plus coffee, plus tea, plus pop, plus fruit juice, we’ll feel guilty when we’re not successful. Water used by the body comes from fluids ingested (5 cups), moisture in foods (4 cups) and fluids produced during metabolic oxidation (1 cup), totaling approximately 10 cups per day in moderate climates. We consume 10 cups of water per day, but only 5 cups come from ingested fluids (not necessarily water), the rest come from foods and our metabolism.

In a 2000 Tufts newsletter, Dr Wayne Campbell, PhD, a researcher at Purdue University said the “8 glasses a day” guideline was mistranslated. The fact is that 8 cups of fluid is necessary for water balance, which includes fluids from foods and metabolic reactions.
In the study, scientists kept track of fluid intake and fluid losses for 12 days. Yes, the subjects did consume close to 8 cups of fluid a day but not only from water, also from decaffeinated beverages and juices. Forty percent of their water needs came from food and ten percent from body processes.

The section on water in a university textbook published 1999, titled Nutrition and edited by Dr. Paul Insel from Stanford University, confirms these accounts of the nutrition experts. (By the way, I contributed to a chapter on a World View of Nutrition). Again the recommended 8 glasses of water includes beverages, food and digestive juices.
Here are some solid recommendations:

Types of Fluids

The five cups of fluids we need can include flavored drinks, milk and fruit juice, not only water.

Foods such as soup, fruits, vegetables and even meat contain water. Haven’t you found you can eat an orange when you’re thirsty, then lose your thirst? That’s because oranges are high in fluids.

Here are some more examples:

Foods: % water
Lettuce, cucumbers and celery: 95
Skim milk: 91
Orange: 87
Banana: 74
Sirloin steak: 59
White bread: 37

Coffee and alcoholic drinks count as fluid. Their very mild diuretic effect encourage water loss through urine. You’ll notice when you have a lot of these drinks, you’re a regular visitor to the washroom. So, don’t drink a lot!

Types of Water

What kind of water is the next question? Can we trust tap water? For that matter, can we trust bottled water? You’ll be pleased to know that any water is fine. Bottled water is not more healthful, more “natural,” or purer than tap water from most municipal systems.
Some people are concerned about the chlorine taste in water. Chlorine is used to disinfect drinking water so that we do not suffer from the deadly illnesses, typhoid and cholera. If you don’t like the taste of your water, use a filter.

Increased Needs

Not only do we need to drink fluids when get thirsty, our intake needs to be increased under certain circumstances. For example:
1. In the elderly - the thirst mechanism is not very sensitive, so they purposefully need to increase their fluid intake beyond the feeling of pure thirst.
2. With vomiting or diarrhea, dehydration can occur. Small sips of liquid, as much as can be tolerated, are recommended during and after these bouts.
3. With heat exhaustion to compensate for sweating and evaporation through the lungs - caused by hot weather.
4. Prolonged exercise, or a strenuous sports event, may blunt the thirst response.
5. Dehydration. You’ll recognize dehydration when you have dark colored urine with a strong odor. Dehydration can lead to tiredness and loss of strength.
6. On long flights – water evaporates from the skin at an accelerated rate in the low-humidity, pressurized cabin of an airplane.

General Recommendation

Drink enough fluids to prevent the onset of thirst; stay “quenched” before thirst sets in. Focus on drinking enough fluids, especially if you have increased needs.
Relax and enjoy decaffeinated, non-alcoholic fluids with flavor.
Don’t feel the need to force 8 glasses of water down your esophagus every day.

Personally, I prefer diet sodas, coffee, tea & milk during the day and only drink water when I exercise, in hot weather, and during the night. Certainly not 8 glasses a day.