You have heard it time and again - drink eight glasses of water a day to stay hydrated. But, this cliched advice lacks scientific evidence, claim scientists.
According to a new study, a recent look at what is known about the health effects of drinking water reveals that most supposed benefits are not backed by solid evidence.
The study indicates that most people do not need to worry about drinking their recommended 8 glasses of 8 ounces ("8x8") of water per day.
While it is clear that humans cannot survive for longer than several days without water, very little research has assessed how average individuals' health is affected by drinking extra fluids.
Ingesting water is helpful for everything from clearing toxins and keeping organs healthy to warding off weight gain and improving skin tone, experts have claimed.
In order to investigate the true benefits of drinking water, Dan Negoianu, MD, and Stanley Goldfarb, MD, of the Renal, Electrolyte, and Hypertension Division at the University of Pennsylvania, in Philadelphia, PA, reviewed the published clinical studies on the topic.
The analysis of the various studies revealed 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.
In addition, no single study indicates that people need to drink the recommended "8x8" amount of water each day. Indeed, it is unclear where this recommendation came from.
The studies, which were reviewed, included - a look at studies related to the notion that increased water intake improves kidney function and helps to clear toxins.
A variety of studies reveal that drinking water does have an impact on clearance of various substances by the kidney, including sodium and urea. However, these studies do not indicate any sort of clinical benefit that might result.
Drs. Negoianu and Goldfarb also investigated the theory that drinking more water will make people feel full and curb their appetite. But studies remain inconclusive.
Headaches also are often attributed to water deprivation, but there are few data to back this up. In addition, water has been touted as an elixir for improved skin tone. While dehydration can decrease skin turgor, no studies have shown any clinical benefit to skin tone as a result of increased water intake.
The study has been published in the Journal of the American Society of Nephrology (JASN).