Doctor: 8 glasses of water a day all wet

GLASGOW, Scotland, July 13 (UPI) -- A primary care physician in Glasgow, Scotland, says there is scant research to back up government advice to drink six to eight glasses of water a day.

In an opinion article published in the British Medical Journal, Margaret McCartney, quotes Heinz Valtin, who in published a critique in 2002 of the evidence for drinking eight glasses a day in the American Journal of Physiology.

"Not only is there no scientific evidence that we need to drink that much, but the recommendation could be harmful," Valtin said.

The harm could lie in a dip in sodium levels in the body, exposure to pollutants and making people feel guilty about drinking enough water, WebMD reported.

McCartney is also critical of the Hydration for Health campaign because the bottled water industry has a vested interest promoting more fluid intake.

The Hydration for Health campaign warns that even mild dehydration can lead to reduced cognitive and physical performance, fatigue, tiredness and constipation.

The British healthcare Web site NHS.uk points out McCartney's article is her opinion and not peer reviewed. The NHS says both of the studies cited by McCartney are American studies that involve the American recommendation to drink eight, 8-ounce glasses of water a day, but for Britain's climate health officials advise about six to eight glasses of water a day.