3 April 2008
Water Intake Guidelines Questioned
by Kate Melville
A meta-study, published in the Journal of the American Society of Nephrology, that looked into the health effects of drinking 8 glasses of water a day revealed that most supposed benefits are not backed by solid evidence. The researchers involved say that most people do not need to worry about drinking the recommended 8 glasses of 8 ounces of water per day.
Surprisingly, very little research has been done into how peoples' health is affected by drinking extra fluids. But "experts" have meanwhile claimed that ingesting water is helpful for everything from clearing toxins and keeping organs healthy to warding off weight gain and improving skin tone.
To investigate the true benefits of drinking water, Dan Negoianu and Stanley Goldfarb at the University of Pennsylvania reviewed the published clinical studies on the topic. They found solid evidence that individuals in hot, dry climates, as well as athletes, have an increased need for water. In addition, people with certain diseases benefit from increased fluid intake. But no such data exist for average, healthy individuals.
Their review also looked at studies related to the notion that increased water intake improves kidney function and helps to clear toxins. While drinking water does have an impact on the clearance of various substances by the kidney, these studies did not indicate any sort of clinical benefit that might result.
The researchers also questioned water's effects on the functioning of organs. They indicate that water retention in the body is variable and depends on the speed with which water is ingested - if it is gulped quickly, water is more likely to be excreted, while if it is sipped slowly, it is retained in the body. However, none of the studies documented any sort of benefit to organs based on increased water intake, regardless of speed.
Negoianu and Goldfarb also pooh-poohed the theory that drinking more water will make people feel full and curb their appetite. In addition, water has been touted as an elixir for improved skin tone, but no studies have shown any clinical benefit to skin tone as a result of increased water intake.
All up, the new study reveals that there is no clear evidence of benefit to increasing water intake. On the other hand, no clear evidence exists of a lack of benefit. "There is simply a lack of evidence in general," noted Negoianu and Goldfarb.
Recommended Water Intake A Myth
Source: American Society of Nephrology