The 8 Glasses Myth: To Drink or Not to Drink Water

Massage therapists as a group advocate getting plenty of water and staying hydrated. In fact, it’s usually the last thing I say to my clients as they head out the door. Last year I blogged about the claim that you needed to drink 8 glasses of water a day – and the fact that there was no serious science backing up that claim. Still, clients who’ve experienced kidney stones know the mantra by heart and follow it, so there’s now some evidence that drinking extra water actually helps kidney function. The NYTimes series called “Really?” looked at some recent studies related to the claim.

The question: Does drinking extra water help kidney function? Here’s what they had to say:

But research over the years has suggested that drinking extra water helps the kidneys clear sodium, urea and toxins from the body. And in the past year, two large studies found a lower risk of long-term kidney problems among people who drink more water and other fluids daily.

via Really? The Claim: Drink Eight Glasses of Water a Day to Protect the Kidneys –

In the first study listed in the article, an Australian team followed 2400 people who were 50 or above. The ones at the upper end of the spectrum, drinking about 3 liters daily, had a “‘significantly lower risk’ of chronic kidney disease.” In the second, Canadian study researchers following over 2100 people for 7 years and found that those who had the highest fluid intake were the least likely to experience a decline in kidney function.

It makes sense that the kidneys would benefit from an increase in water intake. The kidneys use water as a means to filter the blood, remove waste products and balance sodium and calcium levels in the body. The wastes are turned into urine and excreted through the bladder. An increase in hydration would give the body more fluids to use in the filtration process of the kidneys.

Still, the researchers found no evidence that excessive water consumption was healthy for the body. Both of the studies above seemed to indicate a lower risk of kidney function decline with two to three liters of water. Overconsumption of water can be deadly, and the research didn’t advocate flooding the system with water.

As always, a healthy balance is the key. In this case, the balance says around 8 glasses of water a day is beneficial to the kidneys. I’ll drink to that.


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