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"Health and dietary authorities currently encourage Australians to consume eight glasses, or two litres, of fluid daily for optimal health," writes Tsindos.
"This has been misinterpreted to mean two litres of water specifically and it has driven a steady growth in the use of bottled water over the years."
Tsindos believes that encouraging people to drink more water is driven by vested interests, rather than a need for better health. "Thirty years ago you didn't see a plastic water bottle anywhere, now they appear as fashion accessories."
"Research has also revealed that water in food eaten has a greater benefit in weight reduction than avoiding foods altogether. We should be telling people that beverages like tea and coffee contribute to a person's fluid needs and despite their caffeine content, do not lead to dehydration."
"We need to maintain fluid balance and should drink water, but also consider fluid in unprocessed fruits and vegetables and juices."
In an previous review published by the American Journal of Physiology, Heinz Valtin, a Dartmouth Medical School physician reported that there is no supporting evidence to back up the popular recommendation to drink eight 8 oz. glasses of water per day.
How did the 8 X 8 myth start? Valtin thinks that the notion may have started in 1945 when the Food and Nutrition Board of the National Research Council recommended approximately "1 milliliter of water for each calorie of food," which would amount to roughly 2 to 2.5 quarts per day (64 to 80 ounces).
In its next sentence the board stated, "[M]ost of this quantity is contained in prepared foods." But that last sentence seems to have been missed, so that the recommendation was erroneously interpreted as how much water a person should drink each day.
Frederick J. Stare a renowned nutritionist, was a strong supporter of the need to drink at least six glasses of water a day. Nevertheless, he did not support water consumption on spurious scientific foundation. In his criticism of The Stillman Diet, he noted that Dr Stillman claimed consuming eight glasses of water a day was necessary for the kidneys to wash away the fatty acids resulting from the breakdown of fats. The reasoning for this, Dr Stillman admitted, was not fully understood.
Suzanne Douglas, a Los Angeles based Nutritionist says that the 8 glasses of water myth was propagated by the chemical industry an entire decade before the actual mass consumption of bottled water began. "In the 70s and 80s, the myth was promoted by several nutritionists with direct ties to the chemical industry and by the late 80s plastic bottled water began selling worldwide."
The Mayo Clinic looks at both sides of the issue in an article titled, Water: How much should you drink every day? And while they agree people do get a lot of water from certain foods and beverages, "these should not be a major portion of your daily total fluid intake. Water is still your best bet because it's calorie-free, inexpensive and readily available."
Their advice? Listen to your body and drink water accordingly. People who are more active, live in warmer climates, are suffering from an illness or who are pregnant or nursing may need to consume more water, because they are losing more fluids from their bodies than others. As long as you're producing 1.5 litres of light yellow urine a day, you're good to go.
Douglas says that water content in foods is an essential part of our dietary intake and should be included in the total amount of fluid we are required to consume.
Water Content of Foods (In Water Percentage)
Apples: 85
Apricots: 85
Bean sprouts: 92
Chicken, boiled: 71
Cucumbers, raw: 96
Eggplant, raw: 92
Grapes: 82
Lettuce, head: 96
Oranges: 86
Peaches, raw: 90
Peppers, green: 94
Potatoes, raw: 85
Strawberries, raw: 90
Turkey, roasted: 62
Watermelon: 93
Caffeinated beverages and other drinks also should be counted toward daily water intake. University of Nebraska researcher Ann Grandjean and colleagues (Grandjean, 2000) conducted a study, published in the Journal of the American College of Nutrition, about the effects of caffeinated beverages on hydration. Grandjean and her colleagues used 18 healthy male adults for their subjects.
On four separate occasions, the subjects consumed water or water plus varying combinations of beverages. The beverages were carbonated, caffeinated, caloric, and noncaloric colas and coffee. Body weight, urine, and blood evaluations were performed before and after each treatment.
Grandjean found that there were no changes in the body weight, urine, or blood evaluations for the different beverages. The study found no significant differences in the effect of various combinations of beverages on the hydration status of healthy adult males. Grandjean concluded that advising people to disregard caffeinated beverages as part of their daily fluid intake is not supported by the results of her study.
She went on to say, "[T]he purpose of the study was to find out if caffeine was dehydrating in healthy people who are drinking normal amounts. It is not."Â There seems to be a large number of people who hold onto the myth that caffeine causes dehydration, probably because that's what they have always heard.
Under some circumstances, significant fluid intake -- at least eight 8-ounce glasses -- is advisable: for the treatment or prevention of kidney stones, for example, as well as under special circumstances, such as performing strenuous physical activity or enduring hot weather.
The global bottled water sales have increased dramatically over the past several decades, reaching a valuation of around $60 billion and a volume of more than 115,000,000 cubic metres (3.0x1010 US gal) in 2006. U.S. sales reached around 30 billion bottles of water in 2008, a slight drop from 2007 levels.
The global rate of consumption more than quadrupled between 1990 and 2005. Spring water and purified tap water are currently the leading global sellers. By one estimate, approximately 50 billion bottles of water are consumed per annum in the U.S. and around 200 billion bottles globally.
According to Douglas the chemical and plastic industry has benefited by the same proportions and valuation. "The exponential growth and profits generated by global water sales are parallel to the growth experienced by the chemical and plastic industry from 1990 to 2005," she added.
Glasgow-based GP Margaret McCartney says the NHS Choices website's advice that people should drink six to eight glasses a day is 'not only nonsense, but thoroughly debunked nonsense'. She adds that the benefits of the drink are often exaggerated by 'organisations with vested interests' such as bottled water brands.
Writing in the British Medical Journal, Dr McCartney also points out that research shows drinking when not thirsty can impair concentration, rather than boost it, and separate evidence suggests that chemicals used for disinfection found in bottled water could be bad for your health.
Drinking excessive amounts can also lead to loss of sleep as people have to get up in the night to go to the toilet, and other studies show it can even cause kidney damage, instead of preventing it.
The bottom line? Drink when you are thirsty, not because you believe you need to.
April McCarthy is a community journalist playing an active role reporting and analyzing world events to advance our health and eco-friendly initiatives.
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