Nutrition Information

Water, H2 Oh-so-Confusing!
Mike Howard

 

There are very few areas of nutrition that have garnered as much perplexity as the king of all nutrients, and the world’s most prominent substance. Okay, so we all know that water is good for us and that we should drink plenty of it. Exactly how much water we need, however has been the subject of much debate, and remains an enigma to this day. Many medical and nutrition experts are dispelling the 8 - 8Oz. glasses a day gospel – an unsubstantiated idea that has manifested itself into a commonly accepted belief. The origins of the 8 glasses a day recommendation can be traced to Dr. Frederick Stare; a Nutritionist who purported this theory in a book published in 1974. This was simply a best guess on his part, however, as he provided no scientific studies to support his assertion. One could argue that the lucrative bottled water industry is largely responsible for keeping the proverbial 8-a-day flame burning.

Water Intake – Not Just from Water

As it turns out, it is possible that Dr. Stare’s recommendations were simply misinterpreted. Many studies have shown we actually do need at least 8 glasses of water a day. But here’s the catch…that requisite intake is satisfied not only from drinking water, but also from other fluids we consume, the food we eat and the metabolic processes required to break down that food. Juice and milk contribute to hydration and (surprisingly enough) so do caffeinated and alcoholic beverages (caution: moderation is recommended here). Many people still believe that caffeine causes dehydration, even though studies as early as 1928 have shown otherwise . The fluid from food and its accompanying metabolic action alone can account for as much as 6 glasses of water! Water is the best fluid – no argument there. But don’t get caught up in the idiocy of forcing down extra glasses of water if you have a coffee, or if you have been drinking other fluids.

Water – is there such thing as too much?

Like other aspects of health, water is not immune to the “more-must-be-better” mentality that many of us erroneously adopt. Although fatalities due to over-hydration are rare, complications caused by drinking too much water are markedly increasing. To illustrate, 31 runners in the 2000 Houston Marathon were treated for hyponatremia - a condition that can arise with excess fluid consumption, causing a dilution of sodium in the blood. These cases have prompted medical experts to shift away from the previous recommendations of “drinking as much fluid as you can tolerate”, to “drink as needed, but do not exceed 800ml per hour” . This is a potentially important message for serious endurance athletes, who have never given their copious water consumption a second thought.

Other water fallacies

Many of us have heard that thirst is not a good predictor of hydration because by the time we are thirsty, we are dehydrated. This popular contention has been dismissed by many researchers as being generally false – here’s why. The medically accepted definition of dehydration is when a person has lost more than 3% of his/her body weight. Meanwhile, in most cases, our thirst sensation kicks in when less than 2% of body weight is lost . Therefore, under normal circumstances most people can sustain adequate hydration using thirst as an indicator. Another pervasive water myth is the “dark urine = dehydration” theory. Although dark urine may indicate dehydration, there are a multitude of other factors that can contribute to this, and thus it is not an accurate gauge. And yet another popular myth is that water keeps kidney filtration rate at optimal levels. Unless there is an accompanying medical condition, kidney filtration rate only suffers in cases of severe dehydration. We could also use this opportunity to address bottled vs. tap vs. distilled water, but for the sake of brevity – we’ll leave that one alone!

Estimating water needs

• There is a large variation when it comes to individual water needs. Those who are active have increased water requirements, especially if exercising in hot weather.
• As a baseline, 1L of water a day (about 3 glasses) should be fine for those individuals who are relatively sedentary.
• Increasing water intake to 1.5-2.5L/day (4-5 glasses) per day is a good idea if you are moderately to highly active, and drink a few gulps every 15-30 minutes if exercising in hot weather.
• If you are exercising for longer periods of time (going on a long hike, as an example), be sure to consume some salt when consuming large quantities of water.
• If fat loss is your goal, make water your primary beverage – aim for 75% of your fluid consumption, while cutting back on juice, pop and other calorie-containing liquids.


Water – The take-home message

There is no denying that drinking water is vital to our health. It is the hub of all chemical reactions in the body, and is the backbone of any sensible eating plan. Further, the average person probably should be drinking more of the stuff. Having said that, 8 glasses a day will keep most healthy people running to the bathroom all day. Drink water whenever you can – try to have a glass with each meal, and consume it while you are exercising. Use common sense when hydrating during exercising – especially in hot weather. You need not, however count empty bottles, or stress if you were a glass short of what a select few deem “required”.

 

1 Stare, FJ, and McWilliams M. Nutrition for Good Health. Fullerton, CA: Plycon, 1974, p. 175
2 Grandjean, AC, Reimers KJ, Bannick KE, and Haven MC. The effect of caffeinated, non-caffeinated, caloric and non-caloric beverages on hydration. J Am Coll Nutr 19: 591-600, 2000.
3 Tufts University Health and Nutrition Letter. New Consumption Guidelines for Water Sodium, Potassium. April, 2004
4 THE PHYSICIAN AND SPORTSMEDICINE - VOL 31 - NO. 7 - JULY 2003. New Hydration Recommendations.
5 Casa DJ: Proper hydration for distance running: identifying individual fluid needs. Available at http://www.usatf.org.
6 Weinberg, A, and Minaker K. Council of Scientific Affairs, American Medical Association: dehydration evaluation and management in older adults. JAMA 274: 1552-1556, 1995

 

Mike Howard is the owner of Core Concepts Wellness Solutions – a health and fitness services provider that specializes in health seminars, personal training and workplace wellness. He is the author of “Winning the Losing Battle - The Truth about Fat Loss©”, and teaches courses based on the manual in the Greater Vancouver area. For more information, he can be reached at coreconcepts@shaw.ca