Wednesday, June 6, 2012

Eight Glasses of Water a Myth

The common belief that people should drink eight glasses or two litres of water a day is a “myth” that needs debunking, health experts say.

An editorial published today in the Australian and New Zealand Journal of Public Health said exaggerated water needs had driven growth in the bottled water industry.

The author, La Trobe University researcher Spero Tsindos, said a more realistic target was 2L a day total fluid consumption, including the fluids in fruit, vegetables and other beverages.

“Thirty years ago you didn’t see a water bottle anywhere, now they appear as fashion accessories,” he said.

“I think it’s partly this idea that you need to be drinking two litres a day.
“If you’re exercising or you’re sick, sure, you need to keep your fluids up. Otherwise, just drink when you’re thirsty.

“I drink hardly any water but I know my hydration level is healthy because I test it.”

Mr Tsindos said the dehydrating effect of tea and coffee was also a myth.

“Everyone thinks that, but the diuretic effect of tea and coffee is somewhat overrated,” he said.

“We should be educating the general public that beverages like tea and coffee, despite their caffeine content, do not lead to dehydration and will contribute to a person’s fluid needs.”

Dr Trevor Kay, a Perth GP of more than 30 years, said the ‘eight glasses a day’ rule was a misconception doctors dealt with regularly.

“I think it’s a trendy thing to do now, but you don’t need to be carrying a bottle of water around with you,” he said.

“If you have a temperature or it’s 40C and you’re out exercising then you need water.

“But you would do better listening to your body as to how much fluid you need than any prescription.”

He said drinking too much water could be problematic, particularly for the elderly.

“Excess water can lower salt concentrations in the blood, potentially leading to hyponatremia, and it can also lead to fluid on the lungs,” he said.

“Particularly if you’re an elderly person with heart or kidney problems, you need to be careful with your water intake.”

Medical director of Kidney Health Australia, Dr Tim Mathew, said he had tried hard to debunk the myth in recent years.

He said that while water was the best fluid to drink, there was little evidence that eight glasses a day was beneficial. 


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