Busting the eight glasses a day myth

The idea that drinking eight glasses of water a day is good from your health is firmly debunked in a review article published today in the Journal of the American Society of Nephrology (JASN). The authors, two kidney doctors from the University of Pennsylvania, investigated whether expert claims that guzzling the recommended amount of water assists with everything from preventing weight gain to improving skin tone and flushing out toxins. Not only do few clinical studies support this familiar refrain, they write, but they’re not even sure where it came from.

This may sound like good news to anyone who doesn’t pack a water bottle throughout the work day, but the authors also write that the lack of evidence doesn’t mean that drinking lots of water is not beneficial. Very few studies have looked at the question.

But what has been published reveals that filling up on water does not improve the function of the kidneys (though it does help clear out of sodium and urea) or other organs, help people to control their weight by curbing appetite, stave off headaches, or plump up the skin. The studies do show that more fluid is better for people living in hot dry climates, athletes and those with certain diseases.

The JASN review isn’t the first to address this medical myth. An article in the British Medical Journal in December stated that “adequate fluid intake is usually met through typical daily consumption of juice, milk, and even caffeinated drinks.” So it’s probably okay to keep the cuppa coming, as long you listen to your body and quench your thirst.